PLoS Pathog. 2011 Feb 10;7(2):e1001276.
The RON2-AMA1 Interaction is a Critical Step in Moving Junction-Dependent Invasion by Apicomplexan Parasites
Lamarque M, Besteiro S, Papoin J, Roques M, Vulliez-Le Normand B, Morlon-Guyot J, Dubremetz JF, Fauquenoy S, Tomavo S, Faber BW, Kocken CH, Thomas AW, Boulanger MJ, Bentley GA, Lebrun M.
UMR 5235 CNRS, Université de Montpellier 2, Montpellier, France.
Abstract
Obligate intracellular Apicomplexa parasites share a unique invasion mechanism involving a tight interaction between the host cell and the parasite surfaces called the moving junction (MJ). The MJ, which is the anchoring structure for the invasion process, is formed by secretion of a macromolecular complex (RON2/4/5/8), derived from secretory organelles called rhoptries, into the host cell membrane. AMA1, a protein secreted from micronemes and associated with the parasite surface during invasion, has been shown in vitro to bind the MJ complex through a direct association with RON2. Here we show that RON2 is inserted as an integral membrane protein in the host cell and, using several interaction assays with native or recombinant proteins, we define the region that binds AMA1. Our studies were performed both in Toxoplasma gondii and Plasmodium falciparum and although AMA1 and RON2 proteins have diverged between Apicomplexa species, we show an intra-species conservation of their interaction. More importantly, invasion inhibition assays using recombinant proteins demonstrate that the RON2-AMA1 interaction is crucial for both T. gondii and P. falciparum entry into their host cells. This work provides the first evidence that AMA1 uses the rhoptry neck protein RON2 as a receptor to promote invasion by Apicomplexa parasites.
PMID: 21347343 [PubMed - in process]
Saturday, February 26, 2011
Actin Depolymerizing Factor controls actin turnover and gliding motility in Toxoplasma gondii
Mol Biol Cell. 2011 Feb 23. [Epub ahead of print]
Actin Depolymerizing Factor controls actin turnover and gliding motility in Toxoplasma gondii
Mehta S, Sibley LD.
Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110.
Abstract
Apicomplexan parasites rely on actin-based gliding motility to move across the substratum, cross biological barriers, and invade their host cells. Gliding motility depends on polymerization of parasite actin filaments, yet ∼98% of actin is non-filamentous in resting parasites. Previous studies suggest that the lack of actin filaments in the parasite is due to inherent instability, leaving uncertain the role for actin-binding proteins in controlling dynamics. We have previously shown that the single allele of Toxoplasma gondii ADF (TgADF) has strong actin monomer sequestering and weak filament severing activities in vitro. Here we used a conditional knockout strategy to investigate the role of TgADF in vivo. Suppression of TgADF led to accumulation of actin-rich filaments that were detected by immunofluorescence and EM. Parasites deficient in TgADF showed reduced speed of motility, increased aberrant patterns of motion, and inhibition of sustained helical gliding. Lack of TgADF also led to severe defects in entry and egress from host cells, thus blocking infection in vitro. These studies establish that the absence of stable actin structures in the parasite are not simply the result of intrinsic instability, but that TgADF is required for the rapid turnover of parasite actin filaments, gliding motility, and cell invasion.
PMID: 21346192 [PubMed - as supplied by publisher]
Actin Depolymerizing Factor controls actin turnover and gliding motility in Toxoplasma gondii
Mehta S, Sibley LD.
Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110.
Abstract
Apicomplexan parasites rely on actin-based gliding motility to move across the substratum, cross biological barriers, and invade their host cells. Gliding motility depends on polymerization of parasite actin filaments, yet ∼98% of actin is non-filamentous in resting parasites. Previous studies suggest that the lack of actin filaments in the parasite is due to inherent instability, leaving uncertain the role for actin-binding proteins in controlling dynamics. We have previously shown that the single allele of Toxoplasma gondii ADF (TgADF) has strong actin monomer sequestering and weak filament severing activities in vitro. Here we used a conditional knockout strategy to investigate the role of TgADF in vivo. Suppression of TgADF led to accumulation of actin-rich filaments that were detected by immunofluorescence and EM. Parasites deficient in TgADF showed reduced speed of motility, increased aberrant patterns of motion, and inhibition of sustained helical gliding. Lack of TgADF also led to severe defects in entry and egress from host cells, thus blocking infection in vitro. These studies establish that the absence of stable actin structures in the parasite are not simply the result of intrinsic instability, but that TgADF is required for the rapid turnover of parasite actin filaments, gliding motility, and cell invasion.
PMID: 21346192 [PubMed - as supplied by publisher]
Saturday, February 19, 2011
Toxoplasma gondii inhibits granzyme B-mediated apoptosis by the inhibition of granzyme B function in host cells
Int J Parasitol. 2011 Feb 14. [Epub ahead of print]
Toxoplasma gondii inhibits granzyme B-mediated apoptosis by the inhibition of granzyme B function in host cells
Yamada T, Tomita T, Weiss LM, Orlofsky A.
Department of Pathology Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York, 10461, USA.
Abstract
Host defense to the apicomplexan parasite Toxoplasma gondii is critically dependent on CD8(+) T cells, whose effector functions include the induction of apoptosis in target cells following the secretion of granzyme proteases. Here we demonstrate that T. gondii induces resistance of host cells to apoptosis induced by recombinant granzyme B. Granzyme B induction of caspase-independent cytochrome c release was blocked in T. gondii-infected cells. Prevention of apoptosis could not be attributed to altered expression of the Bcl-2 family of apoptotic regulatory proteins, but was instead associated with reduced granzyme B-mediated, caspase-independent cleavage of procaspase 3 to the p20 form in T. gondii-infected cells, as well as reduced granzyme B-mediated cleavage of the artificial granzyme B substrate, GranToxiLux. The reduction in granzyme B proteolytic function in T. gondii-infected cells could not be attributed to altered granzyme B uptake or reduced trafficking of granzyme B to the cytosol, implying a T. gondii-mediated inhibition of granzyme B activity. Apoptosis and GranToxiLux cleavage were similarly inhibited in T. gondii-infected cells exposed to the natural killer-like cell line YT-1. The endogenous granzyme B inhibitor PI-9 was not up-regulated in infected cells. We believe these findings represent the first demonstration of granzyme B inhibition by a cellular pathogen and indicate a new modality for host cell protection by T. gondii that may contribute to parasite immune evasion.
Copyright © 2011. Published by Elsevier Ltd.
PMID: 21329693 [PubMed - as supplied by publisher]
Toxoplasma gondii inhibits granzyme B-mediated apoptosis by the inhibition of granzyme B function in host cells
Yamada T, Tomita T, Weiss LM, Orlofsky A.
Department of Pathology Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York, 10461, USA.
Abstract
Host defense to the apicomplexan parasite Toxoplasma gondii is critically dependent on CD8(+) T cells, whose effector functions include the induction of apoptosis in target cells following the secretion of granzyme proteases. Here we demonstrate that T. gondii induces resistance of host cells to apoptosis induced by recombinant granzyme B. Granzyme B induction of caspase-independent cytochrome c release was blocked in T. gondii-infected cells. Prevention of apoptosis could not be attributed to altered expression of the Bcl-2 family of apoptotic regulatory proteins, but was instead associated with reduced granzyme B-mediated, caspase-independent cleavage of procaspase 3 to the p20 form in T. gondii-infected cells, as well as reduced granzyme B-mediated cleavage of the artificial granzyme B substrate, GranToxiLux. The reduction in granzyme B proteolytic function in T. gondii-infected cells could not be attributed to altered granzyme B uptake or reduced trafficking of granzyme B to the cytosol, implying a T. gondii-mediated inhibition of granzyme B activity. Apoptosis and GranToxiLux cleavage were similarly inhibited in T. gondii-infected cells exposed to the natural killer-like cell line YT-1. The endogenous granzyme B inhibitor PI-9 was not up-regulated in infected cells. We believe these findings represent the first demonstration of granzyme B inhibition by a cellular pathogen and indicate a new modality for host cell protection by T. gondii that may contribute to parasite immune evasion.
Copyright © 2011. Published by Elsevier Ltd.
PMID: 21329693 [PubMed - as supplied by publisher]
Wednesday, February 16, 2011
Toxoplasma gondii sequesters centromeres to a specific nuclear region throughout the cell cycle
Proc Natl Acad Sci U S A. 2011 Feb 14. [Epub ahead of print]
Toxoplasma gondii sequesters centromeres to a specific nuclear region throughout the cell cycle
Brooks CF, Francia ME, Gissot M, Croken MM, Kim K, Striepen B.
Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602.
Abstract
Members of the eukaryotic phylum Apicomplexa are the cause of important human diseases including malaria, toxoplasmosis, and cryptosporidiosis. These obligate intracellular parasites produce new invasive stages through a complex budding process. The budding cycle is remarkably flexible and can produce varied numbers of progeny to adapt to different host-cell niches. How this complex process is coordinated remains poorly understood. Using Toxoplasma gondii as a genetic model, we show that a key element to this coordination is the centrocone, a unique elaboration of the nuclear envelope that houses the mitotic spindle. Exploiting transgenic parasite lines expressing epitope-tagged centromeric H3 variant CenH3, we identify the centromeres of T. gondii chromosomes by hybridization of chromatin immunoprecipitations to genome-wide microarrays (ChIP-chip). We demonstrate that centromere attachment to the centrocone persists throughout the parasite cell cycle and that centromeres localize to a single apical region within the nucleus. Centromere sequestration provides a mechanism for the organization of the Toxoplasma nucleus and the maintenance of genome integrity.
PMID: 21321216 [PubMed - as supplied by publisher]
Toxoplasma gondii sequesters centromeres to a specific nuclear region throughout the cell cycle
Brooks CF, Francia ME, Gissot M, Croken MM, Kim K, Striepen B.
Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602.
Abstract
Members of the eukaryotic phylum Apicomplexa are the cause of important human diseases including malaria, toxoplasmosis, and cryptosporidiosis. These obligate intracellular parasites produce new invasive stages through a complex budding process. The budding cycle is remarkably flexible and can produce varied numbers of progeny to adapt to different host-cell niches. How this complex process is coordinated remains poorly understood. Using Toxoplasma gondii as a genetic model, we show that a key element to this coordination is the centrocone, a unique elaboration of the nuclear envelope that houses the mitotic spindle. Exploiting transgenic parasite lines expressing epitope-tagged centromeric H3 variant CenH3, we identify the centromeres of T. gondii chromosomes by hybridization of chromatin immunoprecipitations to genome-wide microarrays (ChIP-chip). We demonstrate that centromere attachment to the centrocone persists throughout the parasite cell cycle and that centromeres localize to a single apical region within the nucleus. Centromere sequestration provides a mechanism for the organization of the Toxoplasma nucleus and the maintenance of genome integrity.
PMID: 21321216 [PubMed - as supplied by publisher]
Induction of protective Th1 immune responses in mice by vaccination with recombinant Toxoplasma gondii nucleoside triphosphate hydrolase-II
Vaccine. 2011 Feb 9. [Epub ahead of print]
Induction of protective Th1 immune responses in mice by vaccination with recombinant Toxoplasma gondii nucleoside triphosphate hydrolase-II
Tan F, Hu X, Luo FJ, Pan CW, Chen XG.
Department of Parasitology, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, Guangdong 510515, PR China; Department of Parasitology, School of Basic Medical Sciences, Wenzhou Medical College, Wenzhou, Zhejiang 325035, PR China.
Abstract
The Toxoplasma gondii nucleoside triphosphate hydrolase (TgNTPase) has apyrase activity, degrading ATP to the di- and mono-phosphate forms and may be used by the parasite to salvage purines from the host cell for survival and replication. To study the immune-protective value of TgNTPase-II, BALB/c mice were immunized with a recombinant form of the antigen rTgNTPase-II combined with alum. All immunized mice produced specific anti-rTgNTPase-II immunoglobulins, with high IgG antibody titers and a mixed IgG1/IgG2a response, with predominance of IgG2a production. The cellular immune response was associated with the production of IFN-γ and IL-2 cytokines and the increase of the percentage of CD8+ T cells. Vaccinated mice displayed significant protection against acute infection with the virulent RH strain (P<0.05 in survival rate) and also chronic infection with PRU cyst (62.9% and 57.6% reduction in brain parasite load for rTgNTPase-II+alum and rTgNTPase-II alone vaccinated groups) compared to the non-vaccinated control group. In conclusion, rTgNTPase-II elicits a strong specific Th1 immune response providing partial protection against both T. gondii acute and chronic infection.
Copyright © 2011. Published by Elsevier Ltd.
PMID: 21315696 [PubMed - as supplied by publisher]
Induction of protective Th1 immune responses in mice by vaccination with recombinant Toxoplasma gondii nucleoside triphosphate hydrolase-II
Tan F, Hu X, Luo FJ, Pan CW, Chen XG.
Department of Parasitology, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, Guangdong 510515, PR China; Department of Parasitology, School of Basic Medical Sciences, Wenzhou Medical College, Wenzhou, Zhejiang 325035, PR China.
Abstract
The Toxoplasma gondii nucleoside triphosphate hydrolase (TgNTPase) has apyrase activity, degrading ATP to the di- and mono-phosphate forms and may be used by the parasite to salvage purines from the host cell for survival and replication. To study the immune-protective value of TgNTPase-II, BALB/c mice were immunized with a recombinant form of the antigen rTgNTPase-II combined with alum. All immunized mice produced specific anti-rTgNTPase-II immunoglobulins, with high IgG antibody titers and a mixed IgG1/IgG2a response, with predominance of IgG2a production. The cellular immune response was associated with the production of IFN-γ and IL-2 cytokines and the increase of the percentage of CD8+ T cells. Vaccinated mice displayed significant protection against acute infection with the virulent RH strain (P<0.05 in survival rate) and also chronic infection with PRU cyst (62.9% and 57.6% reduction in brain parasite load for rTgNTPase-II+alum and rTgNTPase-II alone vaccinated groups) compared to the non-vaccinated control group. In conclusion, rTgNTPase-II elicits a strong specific Th1 immune response providing partial protection against both T. gondii acute and chronic infection.
Copyright © 2011. Published by Elsevier Ltd.
PMID: 21315696 [PubMed - as supplied by publisher]
Genetic analyses of atypical Toxoplasma gondii strains reveal a fourth clonal lineage in North America
Int J Parasitol. 2011 Feb 11. [Epub ahead of print]
Genetic analyses of atypical Toxoplasma gondii strains reveal a fourth clonal lineage in North America
Khan A, Dubey JP, Su C, Ajioka JW, Rosenthal BM, Sibley LD.
Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, U.S.A.
Abstract
Toxoplasma gondii is a widespread parasite of animals that causes zoonotic infections in humans. Previous studies have revealed a strongly clonal population structure in North America and Europe, while strains from South America are genetically separate and more diverse. However, the composition within North America has been questioned by recent descriptions of genetically more variable strains from this region. Here, we examined an expanded set of isolates using sequenced-based phylogenetic and population analyses to re-evaluate the population structure of T. gondii in North America. Our findings reveal that isolates previously defined by atypical restriction fragment length polymorphism patterns fall into two discrete groups. In one case, these new isolates represent variants of an existing lineage, from which they differ only by minor mutational drift. However, in the second case, it is evident that these isolates define a completely new lineage that is common in North America. Support for this new lineage was based on phylogeny, principle components analysis, STRUCTURE analyses, and statistical analysis of gene flow between groups. This new group, referred to as haplogroup 12, contains divergent genotypes previously referred to as A and X, isolated from sea otters. Consistent with this, group 12 was found primarily in wild animals, as well as occasionally in humans. This new lineage also has a highly clonal population structure. Analysis of the inheritance of multilocus genotypes revealed that different strains within group 12 are the products of a single recombination event between type 2 and a unique parental lineage. Collectively, the archetypal type 2 has been associated with clonal expansion of a small number of lineages in the North, as a consequence of separate but infrequent genetic crosses with several different parental lines.
Copyright © 2011 Australian Society for Parasitology Inc. All rights reserved.
PMID: 21320505 [PubMed - as supplied by publisher]
Genetic analyses of atypical Toxoplasma gondii strains reveal a fourth clonal lineage in North America
Khan A, Dubey JP, Su C, Ajioka JW, Rosenthal BM, Sibley LD.
Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, U.S.A.
Abstract
Toxoplasma gondii is a widespread parasite of animals that causes zoonotic infections in humans. Previous studies have revealed a strongly clonal population structure in North America and Europe, while strains from South America are genetically separate and more diverse. However, the composition within North America has been questioned by recent descriptions of genetically more variable strains from this region. Here, we examined an expanded set of isolates using sequenced-based phylogenetic and population analyses to re-evaluate the population structure of T. gondii in North America. Our findings reveal that isolates previously defined by atypical restriction fragment length polymorphism patterns fall into two discrete groups. In one case, these new isolates represent variants of an existing lineage, from which they differ only by minor mutational drift. However, in the second case, it is evident that these isolates define a completely new lineage that is common in North America. Support for this new lineage was based on phylogeny, principle components analysis, STRUCTURE analyses, and statistical analysis of gene flow between groups. This new group, referred to as haplogroup 12, contains divergent genotypes previously referred to as A and X, isolated from sea otters. Consistent with this, group 12 was found primarily in wild animals, as well as occasionally in humans. This new lineage also has a highly clonal population structure. Analysis of the inheritance of multilocus genotypes revealed that different strains within group 12 are the products of a single recombination event between type 2 and a unique parental lineage. Collectively, the archetypal type 2 has been associated with clonal expansion of a small number of lineages in the North, as a consequence of separate but infrequent genetic crosses with several different parental lines.
Copyright © 2011 Australian Society for Parasitology Inc. All rights reserved.
PMID: 21320505 [PubMed - as supplied by publisher]
Sunday, February 06, 2011
Restoration of T Cell Responses to Toxoplasma gondii after Successful Combined Antiretroviral Therapy in Patients with AIDS with Previous Toxoplasmic
Clin Infect Dis. 2011 Mar;52(5):662-670.
Restoration of T Cell Responses to Toxoplasma gondii after Successful Combined Antiretroviral Therapy in Patients with AIDS with Previous Toxoplasmic Encephalitis
Lejeune M, Miró JM, De Lazzari E, García F, Claramonte X, Martínez E, Ribera E, Arrizabalaga J, Arribas JR, Domingo P, Ferrer E, Plana M, Valls ME, Podzamczer D, Pumarola T, Jacquet A, Mallolas J, Gatell JM, Gallart T; the Spanish Toxoplasma gondii Study Group.
Immunology Service, Hospital Clinic-Institut d'Investigacions Biomèdiques Augustí Pi i Suñer.
Abstract
Background. It is unknown whether a Toxoplasma gondii-specific T cell response is restored after successful combined antiretroviral therapy (cART) in patients with AIDS and current or previous toxoplasmic encephalitis (TE). Methods. We performed a multicenter cross-sectional study with 17 healthy T. gondii-positive human immunodeficiency virus (HIV)-1-uninfected individuals and 90 patients coinfected with HIV-1 and T. gondii distributed in 5 groups according to their CD4(+) T cell counts and T. gondii infection (with or without current or previous TE). We investigated the lymphocyte proliferative response (LPR) and interferon (IFN)-γ production in response to T. gondii soluble antigen extract (SATg) and as CD4(+) and CD8(+) T cell subsets. Results. SATg-specific LPR and IFN-γ production were not observed in many of the most immunosuppressed patients (CD4(+) T cell count, <200 cells/μL, with or without current or previous TE). By contrast, these responses occurred in a considerable percentage (LPR, 43%; IFN-γ production, 80%) of patients receiving successful cART (CD4(+) T cell count, >200 cells/μL) who presented with TE and had already stopped secondary TE prophylaxis. Similar results were found in immunocompetent asymptomatic patients who did not receive TE prophylaxis. The predictors of SATg-specific T cell responses and IFN-γ production were a cART-mediated increase in CD4(+) T cell count and LPR to phytohemagglutinin and viral suppression and a decrease in the activated (CD38(+)) CD8(+) T cell count, respectively. Conclusions. cART restores T. gondii-specific CD4 T cell responses in most patients with AIDS who had previous TE. Our data support the safety of withdrawing TE prophylaxis when the CD4(+) T cell count returns to levels >200 cells/μL.
PMID: 21292671 [PubMed - as supplied by publisher]
Restoration of T Cell Responses to Toxoplasma gondii after Successful Combined Antiretroviral Therapy in Patients with AIDS with Previous Toxoplasmic Encephalitis
Lejeune M, Miró JM, De Lazzari E, García F, Claramonte X, Martínez E, Ribera E, Arrizabalaga J, Arribas JR, Domingo P, Ferrer E, Plana M, Valls ME, Podzamczer D, Pumarola T, Jacquet A, Mallolas J, Gatell JM, Gallart T; the Spanish Toxoplasma gondii Study Group.
Immunology Service, Hospital Clinic-Institut d'Investigacions Biomèdiques Augustí Pi i Suñer.
Abstract
Background. It is unknown whether a Toxoplasma gondii-specific T cell response is restored after successful combined antiretroviral therapy (cART) in patients with AIDS and current or previous toxoplasmic encephalitis (TE). Methods. We performed a multicenter cross-sectional study with 17 healthy T. gondii-positive human immunodeficiency virus (HIV)-1-uninfected individuals and 90 patients coinfected with HIV-1 and T. gondii distributed in 5 groups according to their CD4(+) T cell counts and T. gondii infection (with or without current or previous TE). We investigated the lymphocyte proliferative response (LPR) and interferon (IFN)-γ production in response to T. gondii soluble antigen extract (SATg) and as CD4(+) and CD8(+) T cell subsets. Results. SATg-specific LPR and IFN-γ production were not observed in many of the most immunosuppressed patients (CD4(+) T cell count, <200 cells/μL, with or without current or previous TE). By contrast, these responses occurred in a considerable percentage (LPR, 43%; IFN-γ production, 80%) of patients receiving successful cART (CD4(+) T cell count, >200 cells/μL) who presented with TE and had already stopped secondary TE prophylaxis. Similar results were found in immunocompetent asymptomatic patients who did not receive TE prophylaxis. The predictors of SATg-specific T cell responses and IFN-γ production were a cART-mediated increase in CD4(+) T cell count and LPR to phytohemagglutinin and viral suppression and a decrease in the activated (CD38(+)) CD8(+) T cell count, respectively. Conclusions. cART restores T. gondii-specific CD4 T cell responses in most patients with AIDS who had previous TE. Our data support the safety of withdrawing TE prophylaxis when the CD4(+) T cell count returns to levels >200 cells/μL.
PMID: 21292671 [PubMed - as supplied by publisher]
Thursday, February 03, 2011
Toxoplasma gondii: A bradyzoite-specific DnaK-tetratricopeptide repeat (DnaK-TPR) protein interacts with p23 co-chaperone protein
Exp Parasitol. 2011 Jan 28. [Epub ahead of print]
Toxoplasma gondii: A bradyzoite-specific DnaK-tetratricopeptide repeat (DnaK-TPR) protein interacts with p23 co-chaperone protein
Ueno A, Dautu G, Haga K, Munyaka B, Carmen G, Kobayashi Y, Igarashi M.
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, 2-13 Inada-cho, Obihiro, Hokkaido, 080-8555, Japan; Department of Pathobiological Science, School of Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan.
Abstract
The DnaK-tetratricopeptide repeat (DnaK-TPR) gene (ToxoDB ID, TGME49_002020) is expressed predominantly at the bradyzoite stage. DnaK-TPR protein has a heat shock protein (DnaK) and tetratricopeptide repeat (TPR) domains with amino acid sequence similarity to the counterparts of other organisms (40.2 to 43.7% to DnaK domain and 41.1 to 66.0% to TPR domain). These findings allowed us to infer that DnaK-TPR protein is important in the tachyzoite-to-bradyzoite development or maintenance of cyst structure although the function of this gene is still unknown. An immunofluorescence assay (IFA) revealed that DnaK-TPR protein was expressed in T. gondii-encysted and in vitro-induced bradyzoites and distributed in the whole part of parasite cells. We conducted yeast two-hybrid screening to identify proteins interacting with DnaK-TPR protein, and demonstrated that DnaK-TPR protein interacts with p23 co-chaperone protein (Tgp23). It was expected that DnaK-TPR protein would have a function as a molecular chaperon in bradyzoite cells associated with Tgp23. Possible mechanisms for this gene are discussed.
Copyright © 2011. Published by Elsevier Inc.
PMID: 21281637 [PubMed - as supplied by publisher]
Toxoplasma gondii: A bradyzoite-specific DnaK-tetratricopeptide repeat (DnaK-TPR) protein interacts with p23 co-chaperone protein
Ueno A, Dautu G, Haga K, Munyaka B, Carmen G, Kobayashi Y, Igarashi M.
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, 2-13 Inada-cho, Obihiro, Hokkaido, 080-8555, Japan; Department of Pathobiological Science, School of Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan.
Abstract
The DnaK-tetratricopeptide repeat (DnaK-TPR) gene (ToxoDB ID, TGME49_002020) is expressed predominantly at the bradyzoite stage. DnaK-TPR protein has a heat shock protein (DnaK) and tetratricopeptide repeat (TPR) domains with amino acid sequence similarity to the counterparts of other organisms (40.2 to 43.7% to DnaK domain and 41.1 to 66.0% to TPR domain). These findings allowed us to infer that DnaK-TPR protein is important in the tachyzoite-to-bradyzoite development or maintenance of cyst structure although the function of this gene is still unknown. An immunofluorescence assay (IFA) revealed that DnaK-TPR protein was expressed in T. gondii-encysted and in vitro-induced bradyzoites and distributed in the whole part of parasite cells. We conducted yeast two-hybrid screening to identify proteins interacting with DnaK-TPR protein, and demonstrated that DnaK-TPR protein interacts with p23 co-chaperone protein (Tgp23). It was expected that DnaK-TPR protein would have a function as a molecular chaperon in bradyzoite cells associated with Tgp23. Possible mechanisms for this gene are discussed.
Copyright © 2011. Published by Elsevier Inc.
PMID: 21281637 [PubMed - as supplied by publisher]
Wednesday, February 02, 2011
The activation mechanism of Irga6, an interferon-inducible GTPase contributing to mouse resistance against Toxoplasma gondii
BMC Biol. 2011 Jan 28;9(1):7. [Epub ahead of print]
The activation mechanism of Irga6, an interferon-inducible GTPase contributing to mouse resistance against Toxoplasma gondii
Pawlowski N, Khaminets A, Hunn JP, Papic N, Schmidt A, Uthaiah RC, Lange R, Vopper G, Martens S, Wolf E, Howard JC.
Abstract
ABSTRACT:
BACKGROUND: The interferon-inducible immunity-related GTPases (IRG proteins/p47 GTPases) are a distinctive family of GTPases that function as powerful cell-autonomous resistance factors. The IRG protein, Irga6 (IIGP1), participates in the disruption of the vacuolar membrane surrounding the intracellular parasite, Toxoplasma gondii, through which it communicates with its cellular hosts. Some aspects of the protein's behaviour have suggested a dynamin-like molecular mode of action, in that the energy released by GTP hydrolysis is transduced into mechanical work that results in deformation and ultimately rupture of the vacuolar membrane.
RESULTS: Irga6 forms GTP-dependent oligomers in vitro and thereby activates hydrolysis of the GTP substrate. In this study we define the catalytic G-domain interface by mutagenesis and present a structural model, of how GTP hydrolysis is activated in Irga6 complexes, based on the substrate-twinning reaction mechanism of the signal recognition particle (SRP) and its receptor (SRalpha). In conformity with this model, we show that the bound nucleotide is part of the catalytic interface and that the 3'hydroxyl of the GTP ribose bound to each subunit is essential for trans-activation of hydrolysis of the GTP bound to the other subunit. We show that both positive and negative regulatory interactions between IRG proteins occur via the catalytic interface. Furthermore, mutations that disrupt the catalytic interface also prevent Irga6 from accumulating on the parasitophorous vacuole membrane of T. gondii, showing that GTP-dependent Irga6 activation is an essential component of the resistance mechanism.
CONCLUSIONS: The catalytic interface of Irga6 defined in the present experiments can probably be used as a paradigm for the nucleotide-dependent interactions of all members of the large family of IRG GTPases, both activating and regulatory. Understanding the activation mechanism of Irga6 will help to explain the mechanism by which IRG proteins exercise their resistance function. We find no support from sequence or G-domain structure for the idea that IRG proteins and the SRP GTPases have a common phylogenetic origin. It therefore seems probable, if surprising, that the substrate-assisted catalytic mechanism has been independently evolved in the two protein families.
PMID: 21276251 [PubMed - as supplied by publisher]
The activation mechanism of Irga6, an interferon-inducible GTPase contributing to mouse resistance against Toxoplasma gondii
Pawlowski N, Khaminets A, Hunn JP, Papic N, Schmidt A, Uthaiah RC, Lange R, Vopper G, Martens S, Wolf E, Howard JC.
Abstract
ABSTRACT:
BACKGROUND: The interferon-inducible immunity-related GTPases (IRG proteins/p47 GTPases) are a distinctive family of GTPases that function as powerful cell-autonomous resistance factors. The IRG protein, Irga6 (IIGP1), participates in the disruption of the vacuolar membrane surrounding the intracellular parasite, Toxoplasma gondii, through which it communicates with its cellular hosts. Some aspects of the protein's behaviour have suggested a dynamin-like molecular mode of action, in that the energy released by GTP hydrolysis is transduced into mechanical work that results in deformation and ultimately rupture of the vacuolar membrane.
RESULTS: Irga6 forms GTP-dependent oligomers in vitro and thereby activates hydrolysis of the GTP substrate. In this study we define the catalytic G-domain interface by mutagenesis and present a structural model, of how GTP hydrolysis is activated in Irga6 complexes, based on the substrate-twinning reaction mechanism of the signal recognition particle (SRP) and its receptor (SRalpha). In conformity with this model, we show that the bound nucleotide is part of the catalytic interface and that the 3'hydroxyl of the GTP ribose bound to each subunit is essential for trans-activation of hydrolysis of the GTP bound to the other subunit. We show that both positive and negative regulatory interactions between IRG proteins occur via the catalytic interface. Furthermore, mutations that disrupt the catalytic interface also prevent Irga6 from accumulating on the parasitophorous vacuole membrane of T. gondii, showing that GTP-dependent Irga6 activation is an essential component of the resistance mechanism.
CONCLUSIONS: The catalytic interface of Irga6 defined in the present experiments can probably be used as a paradigm for the nucleotide-dependent interactions of all members of the large family of IRG GTPases, both activating and regulatory. Understanding the activation mechanism of Irga6 will help to explain the mechanism by which IRG proteins exercise their resistance function. We find no support from sequence or G-domain structure for the idea that IRG proteins and the SRP GTPases have a common phylogenetic origin. It therefore seems probable, if surprising, that the substrate-assisted catalytic mechanism has been independently evolved in the two protein families.
PMID: 21276251 [PubMed - as supplied by publisher]
Toxoplasma gondii toxolysin 4 is an extensively processed putative metalloproteinase secreted from micronemes
Mol Biochem Parasitol. 2011 Jan 25. [Epub ahead of print]
Toxoplasma gondii toxolysin 4 is an extensively processed putative metalloproteinase secreted from micronemes
Laliberté J, Carruthers VB.
Department of Microbiology and Immunology, University of Michigan School of Medicine, 1150W. Medical Center Dr., Ann Arbor, MI 48109 USA.
Abstract
Proteases play central roles in cell invasion by Toxoplasma gondii and other apicomplexan parasites. Herein we report the cloning and characterization of a novel secretory putative metalloproteinase, Toxolysin 4 (TLN4). T. gondii tachyzoites store TLN4 in the micronemes and secrete it in response to elevated calcium, suggesting a possible role in cell invasion. TLN4 is initially synthesized as a large (∼260kDa) precursor, which is extensively processed into multiple proteolytic fragments within the parasite secretory system. At least some of these proteolytic fragments remain associated in a large molecular complex. Whereas precomplementation with the TLN4 cDNA allowed disruption of the TLN4 gene, multiple attempts to directly knockout TLN4 without precomplementation failed. TLN4 knockout parasites were detected by PCR in transfected populations but were lost from the cultures during drug selection and growth suggesting that TLN4 contributes to parasite fitness.
Copyright © 2011. Published by Elsevier B.V.
PMID: 21277910 [PubMed - as supplied by publisher]
Toxoplasma gondii toxolysin 4 is an extensively processed putative metalloproteinase secreted from micronemes
Laliberté J, Carruthers VB.
Department of Microbiology and Immunology, University of Michigan School of Medicine, 1150W. Medical Center Dr., Ann Arbor, MI 48109 USA.
Abstract
Proteases play central roles in cell invasion by Toxoplasma gondii and other apicomplexan parasites. Herein we report the cloning and characterization of a novel secretory putative metalloproteinase, Toxolysin 4 (TLN4). T. gondii tachyzoites store TLN4 in the micronemes and secrete it in response to elevated calcium, suggesting a possible role in cell invasion. TLN4 is initially synthesized as a large (∼260kDa) precursor, which is extensively processed into multiple proteolytic fragments within the parasite secretory system. At least some of these proteolytic fragments remain associated in a large molecular complex. Whereas precomplementation with the TLN4 cDNA allowed disruption of the TLN4 gene, multiple attempts to directly knockout TLN4 without precomplementation failed. TLN4 knockout parasites were detected by PCR in transfected populations but were lost from the cultures during drug selection and growth suggesting that TLN4 contributes to parasite fitness.
Copyright © 2011. Published by Elsevier B.V.
PMID: 21277910 [PubMed - as supplied by publisher]
Wednesday, January 12, 2011
The CD40-Autophagy Pathway Is Needed for Host Protection Despite IFN-Γ-Dependent Immunity and CD40 Induces Autophagy via Control of P21 Levels
PLoS One. 2010 Dec 31;5(12):e14472.
The CD40-Autophagy Pathway Is Needed for Host Protection Despite IFN-Γ-Dependent Immunity and CD40 Induces Autophagy via Control of P21 Levels
Portillo JA, Okenka G, Reed E, Subauste A, Van Grol J, Gentil K, Komatsu M, Tanaka K, Landreth G, Levine B, Subauste CS.
Department of Ophthalmology and Visual Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America.
Abstract
Autophagy degrades pathogens in vitro. The autophagy gene Atg5 has been reported to be required for IFN-γ-dependent host protection in vivo. However, these protective effects occur independently of autophagosome formation. Thus, the in vivo role of classic autophagy in protection conferred by adaptive immunity and how adaptive immunity triggers autophagy are incompletely understood. Employing biochemical, genetic and morphological studies, we found that CD40 upregulates the autophagy molecule Beclin 1 in microglia and triggers killing of Toxoplasma gondii dependent on the autophagy machinery. Infected CD40(-/-) mice failed to upregulate Beclin 1 in microglia/macrophages in vivo. Autophagy-deficient Beclin 1(+/-) mice, mice with deficiency of the autophagy protein Atg7 targeted to microglia/macrophages as well as CD40(-/-) mice exhibited impaired killing of T. gondii and were susceptible to cerebral and ocular toxoplasmosis. Susceptibility to toxoplasmosis occurred despite upregulation of IFN-γ, TNF-α and NOS2, preservation of IFN-γ-induced microglia/macrophage anti-T. gondii activity and the generation of anti-T. gondii T cell immunity. CD40 upregulated Beclin 1 and triggered killing of T. gondii by decreasing protein levels of p21, a molecule that degrades Beclin 1. These studies identified CD40-p21-Beclin 1 as a pathway by which adaptive immunity stimulates autophagy. In addition, they support that autophagy is a mechanism through which CD40-dependent immunity mediates in vivo protection and that the CD40-autophagic machinery is needed for host resistance despite IFN-γ.
PMID: 21217818 [PubMed - in process]
The CD40-Autophagy Pathway Is Needed for Host Protection Despite IFN-Γ-Dependent Immunity and CD40 Induces Autophagy via Control of P21 Levels
Portillo JA, Okenka G, Reed E, Subauste A, Van Grol J, Gentil K, Komatsu M, Tanaka K, Landreth G, Levine B, Subauste CS.
Department of Ophthalmology and Visual Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America.
Abstract
Autophagy degrades pathogens in vitro. The autophagy gene Atg5 has been reported to be required for IFN-γ-dependent host protection in vivo. However, these protective effects occur independently of autophagosome formation. Thus, the in vivo role of classic autophagy in protection conferred by adaptive immunity and how adaptive immunity triggers autophagy are incompletely understood. Employing biochemical, genetic and morphological studies, we found that CD40 upregulates the autophagy molecule Beclin 1 in microglia and triggers killing of Toxoplasma gondii dependent on the autophagy machinery. Infected CD40(-/-) mice failed to upregulate Beclin 1 in microglia/macrophages in vivo. Autophagy-deficient Beclin 1(+/-) mice, mice with deficiency of the autophagy protein Atg7 targeted to microglia/macrophages as well as CD40(-/-) mice exhibited impaired killing of T. gondii and were susceptible to cerebral and ocular toxoplasmosis. Susceptibility to toxoplasmosis occurred despite upregulation of IFN-γ, TNF-α and NOS2, preservation of IFN-γ-induced microglia/macrophage anti-T. gondii activity and the generation of anti-T. gondii T cell immunity. CD40 upregulated Beclin 1 and triggered killing of T. gondii by decreasing protein levels of p21, a molecule that degrades Beclin 1. These studies identified CD40-p21-Beclin 1 as a pathway by which adaptive immunity stimulates autophagy. In addition, they support that autophagy is a mechanism through which CD40-dependent immunity mediates in vivo protection and that the CD40-autophagic machinery is needed for host resistance despite IFN-γ.
PMID: 21217818 [PubMed - in process]
Determination of the Viability of Toxoplasma gondii in Cured Ham Using Bioassay
J Food Prot. 2010 Dec;73(12):2239-43.
Determination of the Viability of Toxoplasma gondii in Cured Ham Using Bioassay: Influence of Technological Processing and Food Safety Implications
Bayarri S, Gracia MJ, Lázaro R, Pe Rez-Arquillué C, Barberán M, Herrera A.
Departamento de Producción Animal y Ciencia de los Alimentos;, Email: sbayarri@unizar.es.
Abstract
Toxoplasmosis is a zoonotic disease caused by the protozoan Toxoplasma gondii and distributed worldwide. Ingestion of viable cysts from infected raw or undercooked meat is an important route of horizontal transmission of the parasite to humans. Little information is available concerning the effect of commercial curing on cysts of T. gondii. This study is the first in which the influence of processing of cured ham on the viability of T. gondii has been evaluated, using bioassay to assess the risk of infection from eating this meat product. Naturally infected pigs were selected for the study, and a mouse concentration bioassay technique was used to demonstrate viable bradyzoites of T. gondii in porcine tissues and hams. No viable parasites were found in the final product (14 months of curing) based on results of the indirect immunofluorescence assay and histological and PCR analyses. Our results indicate that the consumption of hams cured as described here poses an insignificant risk of acquiring toxoplasmosis. However, additional studies are required to evaluate the safety of ham products cured under different conditions of curing time, salt, and nitrite concentration.
PMID: 21219742 [PubMed - in process]
Determination of the Viability of Toxoplasma gondii in Cured Ham Using Bioassay: Influence of Technological Processing and Food Safety Implications
Bayarri S, Gracia MJ, Lázaro R, Pe Rez-Arquillué C, Barberán M, Herrera A.
Departamento de Producción Animal y Ciencia de los Alimentos;, Email: sbayarri@unizar.es.
Abstract
Toxoplasmosis is a zoonotic disease caused by the protozoan Toxoplasma gondii and distributed worldwide. Ingestion of viable cysts from infected raw or undercooked meat is an important route of horizontal transmission of the parasite to humans. Little information is available concerning the effect of commercial curing on cysts of T. gondii. This study is the first in which the influence of processing of cured ham on the viability of T. gondii has been evaluated, using bioassay to assess the risk of infection from eating this meat product. Naturally infected pigs were selected for the study, and a mouse concentration bioassay technique was used to demonstrate viable bradyzoites of T. gondii in porcine tissues and hams. No viable parasites were found in the final product (14 months of curing) based on results of the indirect immunofluorescence assay and histological and PCR analyses. Our results indicate that the consumption of hams cured as described here poses an insignificant risk of acquiring toxoplasmosis. However, additional studies are required to evaluate the safety of ham products cured under different conditions of curing time, salt, and nitrite concentration.
PMID: 21219742 [PubMed - in process]
Friday, January 07, 2011
Genomic Data Reveal Toxoplasma gondii Differentiation Mutants Are Also Impaired with Respect to Switching into a Novel Extracellular Tachyzoite State
PLoS One. 2010 Dec 30;5(12):e14463.
Genomic Data Reveal Toxoplasma gondii Differentiation Mutants Are Also Impaired with Respect to Switching into a Novel Extracellular Tachyzoite State
Lescault PJ, Thompson AB, Patil V, Lirussi D, Burton A, Margarit J, Bond J, Matrajt M.
Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, United States of America.
Abstract
Toxoplasma gondii pathogenesis includes the invasion of host cells by extracellular parasites, replication of intracellular tachyzoites, and differentiation to a latent bradyzoite stage. We present the analysis of seven novel T. gondii insertional mutants that do not undergo normal differentiation to bradyzoites. Microarray quantification of the variation in genome-wide RNA levels for each parasite line and times after induction allowed us to describe states in the normal differentiation process, to analyze mutant lines in the context of these states, and to identify genes that may have roles in initiating the transition from tachyzoite to bradyzoite. Gene expression patterns in wild-type parasites undergoing differentiation suggest a novel extracellular state within the tachyzoite stage. All mutant lines exhibit aberrant regulation of bradyzoite gene expression and notably some of the mutant lines appear to exhibit high proportions of the intracellular tachyzoite state regardless of whether they are intracellular or extracellular. In addition to the genes identified by the insertional mutagenesis screen, mixture model analysis allowed us to identify a small number of genes, in mutants, for which expression patterns could not be accounted for using the three parasite states - genes that may play a mechanistic role in switching from the tachyzoite to bradyzoite stage.
PMID: 21209930 [PubMed - in process]
Genomic Data Reveal Toxoplasma gondii Differentiation Mutants Are Also Impaired with Respect to Switching into a Novel Extracellular Tachyzoite State
Lescault PJ, Thompson AB, Patil V, Lirussi D, Burton A, Margarit J, Bond J, Matrajt M.
Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, United States of America.
Abstract
Toxoplasma gondii pathogenesis includes the invasion of host cells by extracellular parasites, replication of intracellular tachyzoites, and differentiation to a latent bradyzoite stage. We present the analysis of seven novel T. gondii insertional mutants that do not undergo normal differentiation to bradyzoites. Microarray quantification of the variation in genome-wide RNA levels for each parasite line and times after induction allowed us to describe states in the normal differentiation process, to analyze mutant lines in the context of these states, and to identify genes that may have roles in initiating the transition from tachyzoite to bradyzoite. Gene expression patterns in wild-type parasites undergoing differentiation suggest a novel extracellular state within the tachyzoite stage. All mutant lines exhibit aberrant regulation of bradyzoite gene expression and notably some of the mutant lines appear to exhibit high proportions of the intracellular tachyzoite state regardless of whether they are intracellular or extracellular. In addition to the genes identified by the insertional mutagenesis screen, mixture model analysis allowed us to identify a small number of genes, in mutants, for which expression patterns could not be accounted for using the three parasite states - genes that may play a mechanistic role in switching from the tachyzoite to bradyzoite stage.
PMID: 21209930 [PubMed - in process]
Thursday, January 06, 2011
Translation control is critical during acute and chronic stages of toxoplasmosis infection
Expert Rev Anti Infect Ther. 2011 Jan;9(1):1-3.
Translation control is critical during acute and chronic stages of toxoplasmosis infection
Joyce BR, Konrad C, Wek RC, Sullivan WJ Jr.
PMID: 21171869 [PubMed - in process]
Translation control is critical during acute and chronic stages of toxoplasmosis infection
Joyce BR, Konrad C, Wek RC, Sullivan WJ Jr.
PMID: 21171869 [PubMed - in process]
Intramembrane Cleavage of AMA1 Triggers Toxoplasma to Switch from an Invasive to a Replicative Mode
Science. 2010 Dec 23. [Epub ahead of print]
Intramembrane Cleavage of AMA1 Triggers Toxoplasma to Switch from an Invasive to a Replicative Mode
Santos JM, Ferguson DJ, Blackman MJ, Soldati-Favre D.
Department of Microbiology, Faculty of Medicine, University of Geneva, 1 rue-Michel Servet, 1211 Geneva 4, Switzerland.
Abstract
Apicomplexan parasites invade host cells and immediately initiate cell division. The extracellular parasite discharges transmembrane proteins onto its surface to mediate motility and invasion. These are shed by intramembrane cleavage, a process associated with invasion but otherwise poorly understood. Functional analysis of Toxoplasma rhomboid 4, a surface intramembrane protease, by conditional overexpression of a catalytically inactive form, produced a profound block in replication. This was completely rescued by expression of the cleaved cytoplasmic tail of Toxoplasma or Plasmodium apical membrane antigen 1 (AMA1). These results reveal an unexpected function for AMA1 in parasite replication, and suggest that invasion proteins help to promote parasite switch from an invasive to a replicative mode.
PMID: 21205639 [PubMed - as supplied by publisher]
Intramembrane Cleavage of AMA1 Triggers Toxoplasma to Switch from an Invasive to a Replicative Mode
Santos JM, Ferguson DJ, Blackman MJ, Soldati-Favre D.
Department of Microbiology, Faculty of Medicine, University of Geneva, 1 rue-Michel Servet, 1211 Geneva 4, Switzerland.
Abstract
Apicomplexan parasites invade host cells and immediately initiate cell division. The extracellular parasite discharges transmembrane proteins onto its surface to mediate motility and invasion. These are shed by intramembrane cleavage, a process associated with invasion but otherwise poorly understood. Functional analysis of Toxoplasma rhomboid 4, a surface intramembrane protease, by conditional overexpression of a catalytically inactive form, produced a profound block in replication. This was completely rescued by expression of the cleaved cytoplasmic tail of Toxoplasma or Plasmodium apical membrane antigen 1 (AMA1). These results reveal an unexpected function for AMA1 in parasite replication, and suggest that invasion proteins help to promote parasite switch from an invasive to a replicative mode.
PMID: 21205639 [PubMed - as supplied by publisher]
Full-parasites: database of full-length cDNAs of apicomplexa parasites, 2010 update
Nucleic Acids Res. 2011 Jan;39(Database issue):D625-31. Epub 2010 Nov 4.
Full-parasites: database of full-length cDNAs of apicomplexa parasites, 2010 update
Tuda J, Mongan AE, Tolba ME, Imada M, Yamagishi J, Xuan X, Wakaguri H, Sugano S, Sugimoto C, Suzuki Y.
Faculty of Medicine, Sam Ratulangi University, Kampus Unsrat, Bahu Manado 95115, Indonesia.
Abstract
Full-Parasites (http://fullmal.hgc.jp/) is a transcriptome database of apicomplexa parasites, which include Plasmodium and Toxoplasma species. The latest version of Full-Parasites contains a total of 105,786 EST sequences from 12 parasites, of which 5925 full-length cDNAs have been completely sequenced. Full-Parasites also contain more than 30 million transcription start sites (TSS) for Plasmodium falciparum (Pf) and Toxoplasma gondii (Tg), which were identified using our novel oligo-capping-based protocol. Various types of cDNA data resources were interconnected with our original database functionalities. Specifically, in this update, we have included two unique RNA-Seq data sets consisting of 730 million mapped RNA-Seq tags. One is a dataset of 16 time-lapse experiments of cultured bradyzoite differentiation for Tg. The other dataset includes 31 clinical samples of Pf. Parasite RNA was extracted together with host human RNA, and the extracted mixed RNA was used for RNA sequencing, with the expectation that gene expression information from the host and parasite would be simultaneously represented. By providing the largest unique full-length cDNA and dynamic transcriptome data, Full-Parasites is useful for understanding host-parasite interactions and will help to eventually elucidate how monophyletic organisms have evolved to become parasites by adopting complex life cycles.
PMID: 21051343 [PubMed - in process]
Full-parasites: database of full-length cDNAs of apicomplexa parasites, 2010 update
Tuda J, Mongan AE, Tolba ME, Imada M, Yamagishi J, Xuan X, Wakaguri H, Sugano S, Sugimoto C, Suzuki Y.
Faculty of Medicine, Sam Ratulangi University, Kampus Unsrat, Bahu Manado 95115, Indonesia.
Abstract
Full-Parasites (http://fullmal.hgc.jp/) is a transcriptome database of apicomplexa parasites, which include Plasmodium and Toxoplasma species. The latest version of Full-Parasites contains a total of 105,786 EST sequences from 12 parasites, of which 5925 full-length cDNAs have been completely sequenced. Full-Parasites also contain more than 30 million transcription start sites (TSS) for Plasmodium falciparum (Pf) and Toxoplasma gondii (Tg), which were identified using our novel oligo-capping-based protocol. Various types of cDNA data resources were interconnected with our original database functionalities. Specifically, in this update, we have included two unique RNA-Seq data sets consisting of 730 million mapped RNA-Seq tags. One is a dataset of 16 time-lapse experiments of cultured bradyzoite differentiation for Tg. The other dataset includes 31 clinical samples of Pf. Parasite RNA was extracted together with host human RNA, and the extracted mixed RNA was used for RNA sequencing, with the expectation that gene expression information from the host and parasite would be simultaneously represented. By providing the largest unique full-length cDNA and dynamic transcriptome data, Full-Parasites is useful for understanding host-parasite interactions and will help to eventually elucidate how monophyletic organisms have evolved to become parasites by adopting complex life cycles.
PMID: 21051343 [PubMed - in process]
Wednesday, January 05, 2011
Strain-specific activation of the NF-{kappa}B pathway by GRA15, a novel Toxoplasma gondii dense granule protein
J Exp Med. 2011 Jan 3. [Epub ahead of print]
Strain-specific activation of the NF-{kappa}B pathway by GRA15, a novel Toxoplasma gondii dense granule protein
Rosowski EE, Lu D, Julien L, Rodda L, Gaiser RA, Jensen KD, Saeij JP.
Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139.
Abstract
NF-κB is an integral component of the immune response to Toxoplasma gondii. Although evidence exists that T. gondii can directly modulate the NF-κB pathway, the parasite-derived effectors involved are unknown. We determined that type II strains of T. gondii activate more NF-κB than type I or type III strains, and using forward genetics we found that this difference is a result of the polymorphic protein GRA15, a novel dense granule protein which T. gondii secretes into the host cell upon invasion. A GRA15-deficient type II strain has a severe defect in both NF-κB nuclear translocation and NF-κB-mediated transcription. Furthermore, human cells expressing type II GRA15 also activate NF-κB, demonstrating that GRA15 alone is sufficient for NF-κB activation. Along with the rhoptry protein ROP16, GRA15 is responsible for a large part of the strain differences in the induction of IL-12 secretion by infected mouse macrophages. In vivo bioluminescent imaging showed that a GRA15-deficient type II strain grows faster compared with wild-type, most likely through its reduced induction of IFN-γ. These results show for the first time that a dense granule protein can modulate host signaling pathways, and dense granule proteins can therefore join rhoptry proteins in T. gondii's host cell-modifying arsenal.
PMID: 21199955 [PubMed - as supplied by publisher]
Strain-specific activation of the NF-{kappa}B pathway by GRA15, a novel Toxoplasma gondii dense granule protein
Rosowski EE, Lu D, Julien L, Rodda L, Gaiser RA, Jensen KD, Saeij JP.
Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139.
Abstract
NF-κB is an integral component of the immune response to Toxoplasma gondii. Although evidence exists that T. gondii can directly modulate the NF-κB pathway, the parasite-derived effectors involved are unknown. We determined that type II strains of T. gondii activate more NF-κB than type I or type III strains, and using forward genetics we found that this difference is a result of the polymorphic protein GRA15, a novel dense granule protein which T. gondii secretes into the host cell upon invasion. A GRA15-deficient type II strain has a severe defect in both NF-κB nuclear translocation and NF-κB-mediated transcription. Furthermore, human cells expressing type II GRA15 also activate NF-κB, demonstrating that GRA15 alone is sufficient for NF-κB activation. Along with the rhoptry protein ROP16, GRA15 is responsible for a large part of the strain differences in the induction of IL-12 secretion by infected mouse macrophages. In vivo bioluminescent imaging showed that a GRA15-deficient type II strain grows faster compared with wild-type, most likely through its reduced induction of IFN-γ. These results show for the first time that a dense granule protein can modulate host signaling pathways, and dense granule proteins can therefore join rhoptry proteins in T. gondii's host cell-modifying arsenal.
PMID: 21199955 [PubMed - as supplied by publisher]
Phosphorylation of Mouse Immunity-Related GTPase (IRG) Resistance Proteins Is an Evasion Strategy for Virulent Toxoplasma gondii
PLoS Biol. 2010 Dec 21;8(12):e1000576.
Phosphorylation of Mouse Immunity-Related GTPase (IRG) Resistance Proteins Is an Evasion Strategy for Virulent Toxoplasma gondii
Steinfeldt T, Könen-Waisman S, Tong L, Pawlowski N, Lamkemeyer T, Sibley LD, Hunn JP, Howard JC.
Institute for Genetics, University of Cologne, Cologne, Germany.
Abstract
Virulence of complex pathogens in mammals is generally determined by multiple components of the pathogen interacting with the functional complexity and multiple layering of the mammalian immune system. It is most unusual for the resistance of a mammalian host to be overcome by the defeat of a single defence mechanism. In this study we uncover and analyse just such a case at the molecular level, involving the widespread intracellular protozoan pathogen Toxoplasma gondii and one of its most important natural hosts, the house mouse (Mus musculus). Natural polymorphism in virulence of Eurasian T. gondii strains for mice has been correlated in genetic screens with the expression of polymorphic rhoptry kinases (ROP kinases) secreted into the host cell during infection. We show that the molecular targets of the virulent allelic form of ROP18 kinase are members of a family of cellular GTPases, the interferon-inducible IRG (immunity-related GTPase) proteins, known from earlier work to be essential resistance factors in mice against avirulent strains of T. gondii. Virulent T. gondii strain ROP18 kinase phosphorylates several mouse IRG proteins. We show that the parasite kinase phosphorylates host Irga6 at two threonines in the nucleotide-binding domain, biochemically inactivating the GTPase and inhibiting its accumulation and action at the T. gondii parasitophorous vacuole membrane. Our analysis identifies the conformationally active switch I region of the GTP-binding site as an Achilles' heel of the IRG protein pathogen-resistance mechanism. The polymorphism of ROP18 in natural T. gondii populations indicates the existence of a dynamic, rapidly evolving ecological relationship between parasite virulence factors and host resistance factors. This system should be unusually fruitful for analysis at both ecological and molecular levels since both T. gondii and the mouse are widespread and abundant in the wild and are well-established model species with excellent analytical tools available.
PMID: 21203588 [PubMed - in process]
Phosphorylation of Mouse Immunity-Related GTPase (IRG) Resistance Proteins Is an Evasion Strategy for Virulent Toxoplasma gondii
Steinfeldt T, Könen-Waisman S, Tong L, Pawlowski N, Lamkemeyer T, Sibley LD, Hunn JP, Howard JC.
Institute for Genetics, University of Cologne, Cologne, Germany.
Abstract
Virulence of complex pathogens in mammals is generally determined by multiple components of the pathogen interacting with the functional complexity and multiple layering of the mammalian immune system. It is most unusual for the resistance of a mammalian host to be overcome by the defeat of a single defence mechanism. In this study we uncover and analyse just such a case at the molecular level, involving the widespread intracellular protozoan pathogen Toxoplasma gondii and one of its most important natural hosts, the house mouse (Mus musculus). Natural polymorphism in virulence of Eurasian T. gondii strains for mice has been correlated in genetic screens with the expression of polymorphic rhoptry kinases (ROP kinases) secreted into the host cell during infection. We show that the molecular targets of the virulent allelic form of ROP18 kinase are members of a family of cellular GTPases, the interferon-inducible IRG (immunity-related GTPase) proteins, known from earlier work to be essential resistance factors in mice against avirulent strains of T. gondii. Virulent T. gondii strain ROP18 kinase phosphorylates several mouse IRG proteins. We show that the parasite kinase phosphorylates host Irga6 at two threonines in the nucleotide-binding domain, biochemically inactivating the GTPase and inhibiting its accumulation and action at the T. gondii parasitophorous vacuole membrane. Our analysis identifies the conformationally active switch I region of the GTP-binding site as an Achilles' heel of the IRG protein pathogen-resistance mechanism. The polymorphism of ROP18 in natural T. gondii populations indicates the existence of a dynamic, rapidly evolving ecological relationship between parasite virulence factors and host resistance factors. This system should be unusually fruitful for analysis at both ecological and molecular levels since both T. gondii and the mouse are widespread and abundant in the wild and are well-established model species with excellent analytical tools available.
PMID: 21203588 [PubMed - in process]
TgVTC2 is Involved in Polyphosphate Accumulation in Toxoplasma gondii
Mol Biochem Parasitol. 2010 Dec 29. [Epub ahead of print]
TgVTC2 is Involved in Polyphosphate Accumulation in Toxoplasma gondii
Rooney PJ, Ayong L, Tobin CM, Moreno SN, Knoll LJ.
Department of Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Microbial Sciences Building Room 3345, 1550 Linden Drive, Madison, WI 53706, United States.
Abstract
Polyphosphate is found in every cell, having roles in diverse processes, including differentiation and response to stress. In this study, we characterize a Toxoplasma gondii mutant containing an insertion within the carboxy-terminal end of a homolog of Saccharomyces cerevisiae Vtc2p, a component of the polyphosphate synthetic machinery. Locus TgVTC2 encodes a 140kDa protein containing conserved SPX, VTC and transmembrane domains. TgVTC2 localizes in punctate spots within the cytoplasm that do not co-localize with known markers. The TgVTC2 mutant showed dramatically reduced polyphosphate accumulation, a defect restored by introduction of TgVTC2 to the mutant. Insertion within TgVTC2 resulted in increased transcript levels for two loci, including a putative FIKK kinase. These transcript levels were restored to wild-type levels upon complementation with the TgVTC2 locus. The TgVTC2 locus was refractory to knockout, and may be essential. Analysis of this TgVTC2 mutant will facilitate dissection of the T. gondii polyphosphate synthesis pathway.
Copyright © 2010. Published by Elsevier B.V.
PMID: 21195114 [PubMed - as supplied by publisher]
TgVTC2 is Involved in Polyphosphate Accumulation in Toxoplasma gondii
Rooney PJ, Ayong L, Tobin CM, Moreno SN, Knoll LJ.
Department of Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Microbial Sciences Building Room 3345, 1550 Linden Drive, Madison, WI 53706, United States.
Abstract
Polyphosphate is found in every cell, having roles in diverse processes, including differentiation and response to stress. In this study, we characterize a Toxoplasma gondii mutant containing an insertion within the carboxy-terminal end of a homolog of Saccharomyces cerevisiae Vtc2p, a component of the polyphosphate synthetic machinery. Locus TgVTC2 encodes a 140kDa protein containing conserved SPX, VTC and transmembrane domains. TgVTC2 localizes in punctate spots within the cytoplasm that do not co-localize with known markers. The TgVTC2 mutant showed dramatically reduced polyphosphate accumulation, a defect restored by introduction of TgVTC2 to the mutant. Insertion within TgVTC2 resulted in increased transcript levels for two loci, including a putative FIKK kinase. These transcript levels were restored to wild-type levels upon complementation with the TgVTC2 locus. The TgVTC2 locus was refractory to knockout, and may be essential. Analysis of this TgVTC2 mutant will facilitate dissection of the T. gondii polyphosphate synthesis pathway.
Copyright © 2010. Published by Elsevier B.V.
PMID: 21195114 [PubMed - as supplied by publisher]
Foodborne illness acquired in the United States-major pathogens
Emerg Infect Dis. 2011 Jan;17(1):7-15.
Foodborne illness acquired in the United States-major pathogens
Scallan E, Hoekstra RM, Angulo FJ, Tauxe RV, Widdowson MA, Roy SL, Jones JL, Griffin PM.
Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
Abstract
Estimates of foodborne illness can be used to direct food safety policy and interventions. We used data from active and passive surveillance and other sources to estimate that each year 31 major pathogens acquired in the United States caused 9.4 million episodes of foodborne illness (90% credible interval [CrI] 6.6-12.7 million), 55,961 hospitalizations (90% CrI 39,534-75,741), and 1,351 deaths (90% CrI 712-2,268). Most (58%) illnesses were caused by norovirus, followed by nontyphoidal Salmonella spp. (11%), Clostridium perfringens (10%), and Campylobacter spp. (9%). Leading causes of hospitalization were nontyphoidal Salmonella spp. (35%), norovirus (26%), Campylobacter spp. (15%), and Toxoplasma gondii (8%). Leading causes of death were nontyphoidal Salmonella spp. (28%), T. gondii (24%), Listeria monocytogenes (19%), and norovirus (11%). These estimates cannot be compared with prior (1999) estimates to assess trends because different methods were used. Additional data and more refined methods can improve future estimates.
PMID: 21192848 [PubMed - in process]
Foodborne illness acquired in the United States-major pathogens
Scallan E, Hoekstra RM, Angulo FJ, Tauxe RV, Widdowson MA, Roy SL, Jones JL, Griffin PM.
Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
Abstract
Estimates of foodborne illness can be used to direct food safety policy and interventions. We used data from active and passive surveillance and other sources to estimate that each year 31 major pathogens acquired in the United States caused 9.4 million episodes of foodborne illness (90% credible interval [CrI] 6.6-12.7 million), 55,961 hospitalizations (90% CrI 39,534-75,741), and 1,351 deaths (90% CrI 712-2,268). Most (58%) illnesses were caused by norovirus, followed by nontyphoidal Salmonella spp. (11%), Clostridium perfringens (10%), and Campylobacter spp. (9%). Leading causes of hospitalization were nontyphoidal Salmonella spp. (35%), norovirus (26%), Campylobacter spp. (15%), and Toxoplasma gondii (8%). Leading causes of death were nontyphoidal Salmonella spp. (28%), T. gondii (24%), Listeria monocytogenes (19%), and norovirus (11%). These estimates cannot be compared with prior (1999) estimates to assess trends because different methods were used. Additional data and more refined methods can improve future estimates.
PMID: 21192848 [PubMed - in process]
Self-Mating in the Definitive Host Potentiates Clonal Outbreaks of the Apicomplexan Parasites Sarcocystis neurona and Toxoplasma gondii
PLoS Genet. 2010 Dec 23;6(12):e1001261.
Self-Mating in the Definitive Host Potentiates Clonal Outbreaks of the Apicomplexan Parasites Sarcocystis neurona and Toxoplasma gondii
Wendte JM, Miller MA, Lambourn DM, Magargal SL, Jessup DA, Grigg ME.
Molecular Parasitology Unit, Laboratory of Parasitic Diseases, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.
Abstract
Tissue-encysting coccidia, including Toxoplasma gondii and Sarcocystis neurona, are heterogamous parasites with sexual and asexual life stages in definitive and intermediate hosts, respectively. During its sexual life stage, T. gondii reproduces either by genetic out-crossing or via clonal amplification of a single strain through self-mating. Out-crossing has been experimentally verified as a potent mechanism capable of producing offspring possessing a range of adaptive and virulence potentials. In contrast, selfing and other life history traits, such as asexual expansion of tissue-cysts by oral transmission among intermediate hosts, have been proposed to explain the genetic basis for the clonal population structure of T. gondii. In this study, we investigated the contributing roles self-mating and sexual recombination play in nature to maintain clonal population structures and produce or expand parasite clones capable of causing disease epidemics for two tissue encysting parasites. We applied high-resolution genotyping against strains isolated from a T. gondii waterborne outbreak that caused symptomatic disease in 155 immune-competent people in Brazil and a S. neurona outbreak that resulted in a mass mortality event in Southern sea otters. In both cases, a single, genetically distinct clone was found infecting outbreak-exposed individuals. Furthermore, the T. gondii outbreak clone was one of several apparently recombinant progeny recovered from the local environment. Since oocysts or sporocysts were the infectious form implicated in each outbreak, the expansion of the epidemic clone can be explained by self-mating. The results also show that out-crossing preceded selfing to produce the virulent T. gondii clone. For the tissue encysting coccidia, self-mating exists as a key adaptation potentiating the epidemic expansion and transmission of newly emerged parasite clones that can profoundly shape parasite population genetic structures or cause devastating disease outbreaks.
PMID: 21203443 [PubMed - in process]
Self-Mating in the Definitive Host Potentiates Clonal Outbreaks of the Apicomplexan Parasites Sarcocystis neurona and Toxoplasma gondii
Wendte JM, Miller MA, Lambourn DM, Magargal SL, Jessup DA, Grigg ME.
Molecular Parasitology Unit, Laboratory of Parasitic Diseases, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.
Abstract
Tissue-encysting coccidia, including Toxoplasma gondii and Sarcocystis neurona, are heterogamous parasites with sexual and asexual life stages in definitive and intermediate hosts, respectively. During its sexual life stage, T. gondii reproduces either by genetic out-crossing or via clonal amplification of a single strain through self-mating. Out-crossing has been experimentally verified as a potent mechanism capable of producing offspring possessing a range of adaptive and virulence potentials. In contrast, selfing and other life history traits, such as asexual expansion of tissue-cysts by oral transmission among intermediate hosts, have been proposed to explain the genetic basis for the clonal population structure of T. gondii. In this study, we investigated the contributing roles self-mating and sexual recombination play in nature to maintain clonal population structures and produce or expand parasite clones capable of causing disease epidemics for two tissue encysting parasites. We applied high-resolution genotyping against strains isolated from a T. gondii waterborne outbreak that caused symptomatic disease in 155 immune-competent people in Brazil and a S. neurona outbreak that resulted in a mass mortality event in Southern sea otters. In both cases, a single, genetically distinct clone was found infecting outbreak-exposed individuals. Furthermore, the T. gondii outbreak clone was one of several apparently recombinant progeny recovered from the local environment. Since oocysts or sporocysts were the infectious form implicated in each outbreak, the expansion of the epidemic clone can be explained by self-mating. The results also show that out-crossing preceded selfing to produce the virulent T. gondii clone. For the tissue encysting coccidia, self-mating exists as a key adaptation potentiating the epidemic expansion and transmission of newly emerged parasite clones that can profoundly shape parasite population genetic structures or cause devastating disease outbreaks.
PMID: 21203443 [PubMed - in process]
Wednesday, December 29, 2010
Host Cholesterol Synthesis Contributes to Growth of Intracellular Toxoplasma gondii in Macrophages
J Vet Med Sci. 2010 Dec 24. [Epub ahead of print]
Host Cholesterol Synthesis Contributes to Growth of Intracellular Toxoplasma gondii in Macrophages
Nishikawa Y, Ibrahim HM, Kameyama K, Shiga I, Hiasa J, Xuan X.
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine.
Abstract
The intracellular protozoan Toxoplasma gondii lacks the ability to synthesize sterol and scavenges cholesterol from the low-density lipoprotein receptor (LDLR) pathway of its host to facilitate replication. Sterol biosynthesis inhibitors, however, have a demonstrated anti-Toxoplasma effect. In this study, we examined the host mevalonate pathway as a novel source of cholesterol for T. gondii and its effects on parasite growth in macrophages. Parasite growth did not significantly change in the absence of LDLR or when LDL was exogenously supplemented. Lovastatin and compactin, both inhibitors of hydroxymethylglutaryl-CoA (HMG-CoA) reductase in the mevalonate pathway, significantly inhibited T. gondii growth in both wild-type and LDLR-knockout macrophages. Parasite growth was also suppressed by squalestatin, an inhibitor of squalene synthase, despite mevalonate producing isoprenoid intermediates in host cells. The present study demonstrates that lovastatin, compactin and squalestatin have anti-Toxoplasma activities and that the host cholesterol synthesis may contribute to parasite growth in macrophages.
PMID: 21187676
Host Cholesterol Synthesis Contributes to Growth of Intracellular Toxoplasma gondii in Macrophages
Nishikawa Y, Ibrahim HM, Kameyama K, Shiga I, Hiasa J, Xuan X.
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine.
Abstract
The intracellular protozoan Toxoplasma gondii lacks the ability to synthesize sterol and scavenges cholesterol from the low-density lipoprotein receptor (LDLR) pathway of its host to facilitate replication. Sterol biosynthesis inhibitors, however, have a demonstrated anti-Toxoplasma effect. In this study, we examined the host mevalonate pathway as a novel source of cholesterol for T. gondii and its effects on parasite growth in macrophages. Parasite growth did not significantly change in the absence of LDLR or when LDL was exogenously supplemented. Lovastatin and compactin, both inhibitors of hydroxymethylglutaryl-CoA (HMG-CoA) reductase in the mevalonate pathway, significantly inhibited T. gondii growth in both wild-type and LDLR-knockout macrophages. Parasite growth was also suppressed by squalestatin, an inhibitor of squalene synthase, despite mevalonate producing isoprenoid intermediates in host cells. The present study demonstrates that lovastatin, compactin and squalestatin have anti-Toxoplasma activities and that the host cholesterol synthesis may contribute to parasite growth in macrophages.
PMID: 21187676
Tuesday, December 28, 2010
Toxoplasma gondii: humoral and cellular immune response of BALB/c mice immunized via intranasal route with rTgROP2
Rev Bras Parasitol Vet. 2010 Oct-Dec;19(4):210-6.
Toxoplasma gondii: humoral and cellular immune response of BALB/c mice immunized via intranasal route with rTgROP2
Igarashi M, Zulpo DL, Cunha IA, Barros LD, Pereira VF, Taroda A, Navarro I, Vidotto O, Vidotto MC, Jenkins MC, Garcia JL.
Laboratório de Protozoologia, Departamento de Medicina Veterinária Preventiva, Universidade de Londrina - UEL, CP 6001, CEP 86050-970Londrina - PR, Brazil. jlgarcia@uel.br.
Abstract
TgROP2 is an intracellular protein associated with rhoptries of Toxoplama gondii and an antigen component of a candidate vaccine for toxoplasmosis. The purpose of the present study was to evaluate the efficacy of rTgROP2 to stimulate humoral and cellular immune responses in BALB/c mice via intranasal injection. TgROP2 partial coding sequence was (196-561) amplified by PCR from genomic T. gondii RH strain DNA and cloned into the pTrcHis expression vector. Escherichia coli Rosetta 2 cells transformed with pTrcHis-TgROP2 showed high levels (~1 mg.mL(-1)) of recombinant protein after 4 hours of IPTG induction. Recombinant TgROP2 exhibited an apparent Mr equal to 54 kDa. In order to test immunogenicity of the recombinant protein, 10 BALB/c mice received 10 µg of rROP2 protein + 10 µg of Quil-A via intranasal injection. Doses were administered at days 0, 21, and 42. Three animals were euthanized and used to evaluate cell-ular immune response on day 62. Five (50%) and two (20%) out of ten animals produced IgG (DO mean = 0.307; cut-off = 0.240) and IgA (DO mean = 0.133, cut-off = 0.101), respectively, by ELISA on day 62. The proliferation of splenocytes revealed high stimulation index (SI) when co-cultured with 5, 10 and 15 µg.mL(-1) of rTgROP2. These results indicate that intranasal immunization with recombinant protein ROP2 plus Quil-A can elicit both cellular and humoral immune responses in BALB/c mice.
PMID: 21184696
Toxoplasma gondii: humoral and cellular immune response of BALB/c mice immunized via intranasal route with rTgROP2
Igarashi M, Zulpo DL, Cunha IA, Barros LD, Pereira VF, Taroda A, Navarro I, Vidotto O, Vidotto MC, Jenkins MC, Garcia JL.
Laboratório de Protozoologia, Departamento de Medicina Veterinária Preventiva, Universidade de Londrina - UEL, CP 6001, CEP 86050-970Londrina - PR, Brazil. jlgarcia@uel.br.
Abstract
TgROP2 is an intracellular protein associated with rhoptries of Toxoplama gondii and an antigen component of a candidate vaccine for toxoplasmosis. The purpose of the present study was to evaluate the efficacy of rTgROP2 to stimulate humoral and cellular immune responses in BALB/c mice via intranasal injection. TgROP2 partial coding sequence was (196-561) amplified by PCR from genomic T. gondii RH strain DNA and cloned into the pTrcHis expression vector. Escherichia coli Rosetta 2 cells transformed with pTrcHis-TgROP2 showed high levels (~1 mg.mL(-1)) of recombinant protein after 4 hours of IPTG induction. Recombinant TgROP2 exhibited an apparent Mr equal to 54 kDa. In order to test immunogenicity of the recombinant protein, 10 BALB/c mice received 10 µg of rROP2 protein + 10 µg of Quil-A via intranasal injection. Doses were administered at days 0, 21, and 42. Three animals were euthanized and used to evaluate cell-ular immune response on day 62. Five (50%) and two (20%) out of ten animals produced IgG (DO mean = 0.307; cut-off = 0.240) and IgA (DO mean = 0.133, cut-off = 0.101), respectively, by ELISA on day 62. The proliferation of splenocytes revealed high stimulation index (SI) when co-cultured with 5, 10 and 15 µg.mL(-1) of rTgROP2. These results indicate that intranasal immunization with recombinant protein ROP2 plus Quil-A can elicit both cellular and humoral immune responses in BALB/c mice.
PMID: 21184696
High level of soluble HLA-G in amniotic fluid is correlated with congenital transmission of Toxoplasma gondii
Clin Immunol. 2010 Dec 23. [Epub ahead of print]
High level of soluble HLA-G in amniotic fluid is correlated with congenital transmission of Toxoplasma gondii
Robert-Gangneux F, Gangneux JP, Vu N, Jaillard S, Guiguen C, Amiot L.
Laboratoire de Parasitologie, Faculté de Médecine et Centre Hospitalier Universitaire de Rennes, Rennes, France; Unité EA4427-SERAIC (Signalisation et réponse aux agents infectieux et chimiques), IRSET (Institut de Recherche en Santé Environnement Travail), Université Rennes 1, Rennes, France.
Abstract
The expression of human leukocyte antigen (HLA)-G on cytotrophoblast cells contributes to maternal-fetal tolerance. Soluble forms of HLA-G (sHLA-G) can be detected in amniotic fluid (AF) and a decrease of sHLA-G is known to be correlated to fetal loss. In this work we investigated the role of sHLA-G in the transplacental passage of the protozoan parasite Toxoplasma gondii, responsible for congenital toxoplasmosis in about 30% of fetuses when primary infection (PI) occurs during pregnancy. We determined the sHLA-G concentration in 61 AF from women with PI and 24 controls. Our results showed higher sHLA-G levels in AF from PI than in controls (p<0.001). Moreover sHLA-G level from congenitally infected fetuses (n=12) was higher than in fetus in whom congenital infection was ruled out (n=49, p<0.05). These data suggest that sHLA-G could participate in immunomodulation necessary to avoid fetal loss due to Toxoplasma infection, but that over-expression could favor congenital transmission.
Copyright © 2010. Published by Elsevier Inc.
PMID: 21185786
High level of soluble HLA-G in amniotic fluid is correlated with congenital transmission of Toxoplasma gondii
Robert-Gangneux F, Gangneux JP, Vu N, Jaillard S, Guiguen C, Amiot L.
Laboratoire de Parasitologie, Faculté de Médecine et Centre Hospitalier Universitaire de Rennes, Rennes, France; Unité EA4427-SERAIC (Signalisation et réponse aux agents infectieux et chimiques), IRSET (Institut de Recherche en Santé Environnement Travail), Université Rennes 1, Rennes, France.
Abstract
The expression of human leukocyte antigen (HLA)-G on cytotrophoblast cells contributes to maternal-fetal tolerance. Soluble forms of HLA-G (sHLA-G) can be detected in amniotic fluid (AF) and a decrease of sHLA-G is known to be correlated to fetal loss. In this work we investigated the role of sHLA-G in the transplacental passage of the protozoan parasite Toxoplasma gondii, responsible for congenital toxoplasmosis in about 30% of fetuses when primary infection (PI) occurs during pregnancy. We determined the sHLA-G concentration in 61 AF from women with PI and 24 controls. Our results showed higher sHLA-G levels in AF from PI than in controls (p<0.001). Moreover sHLA-G level from congenitally infected fetuses (n=12) was higher than in fetus in whom congenital infection was ruled out (n=49, p<0.05). These data suggest that sHLA-G could participate in immunomodulation necessary to avoid fetal loss due to Toxoplasma infection, but that over-expression could favor congenital transmission.
Copyright © 2010. Published by Elsevier Inc.
PMID: 21185786
Saturday, December 25, 2010
Toxoplasma gondii Lysine Acetyltransferase GCN5-A Functions in the Cellular Response to Alkaline Stress and Expression of Cyst Genes
PLoS Pathog. 2010 Dec 16;6(12):e1001232.
Toxoplasma gondii Lysine Acetyltransferase GCN5-A Functions in the Cellular Response to Alkaline Stress and Expression of Cyst Genes
Naguleswaran A, Elias EV, McClintick J, Edenberg HJ, Sullivan WJ.
Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
Abstract
Parasitic protozoa such as the apicomplexan Toxoplasma gondii progress through their life cycle in response to stimuli in the environment or host organism. Very little is known about how proliferating tachyzoites reprogram their expressed genome in response to stresses that prompt development into latent bradyzoite cysts. We have previously linked histone acetylation with the expression of stage-specific genes, but the factors involved remain to be determined. We sought to determine if GCN5, which operates as a transcriptional co-activator by virtue of its histone acetyltransferase (HAT) activity, contributed to stress-induced changes in gene expression in Toxoplasma. In contrast to other lower eukaryotes, Toxoplasma has duplicated its GCN5 lysine acetyltransferase (KAT). Disruption of the gene encoding for TgGCN5-A in type I RH strain did not produce a severe phenotype under normal culture conditions, but here we show that the TgGCN5-A null mutant is deficient in responding to alkaline pH, a common stress used to induce bradyzoite differentiation in vitro. We performed a genome-wide analysis of the Toxoplasma transcriptional response to alkaline pH stress, finding that parasites deleted for TgGCN5-A fail to up-regulate 74% of the stress response genes that are induced 2-fold or more in wild-type. Using chromatin immunoprecipitation, we verify an enrichment of TgGCN5-A at the upstream regions of genes activated by alkaline pH exposure. The TgGCN5-A knockout is also incapable of up-regulating key marker genes expressed during development of the latent cyst form, and is impaired in its ability to recover from alkaline stress. Complementation of the TgGCN5-A knockout restores the expression of these stress-induced genes and reverses the stress recovery defect. These results establish TgGCN5-A as a major contributor to the alkaline stress response in RH strain Toxoplasma.
PMID: 21179246
Toxoplasma gondii Lysine Acetyltransferase GCN5-A Functions in the Cellular Response to Alkaline Stress and Expression of Cyst Genes
Naguleswaran A, Elias EV, McClintick J, Edenberg HJ, Sullivan WJ.
Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
Abstract
Parasitic protozoa such as the apicomplexan Toxoplasma gondii progress through their life cycle in response to stimuli in the environment or host organism. Very little is known about how proliferating tachyzoites reprogram their expressed genome in response to stresses that prompt development into latent bradyzoite cysts. We have previously linked histone acetylation with the expression of stage-specific genes, but the factors involved remain to be determined. We sought to determine if GCN5, which operates as a transcriptional co-activator by virtue of its histone acetyltransferase (HAT) activity, contributed to stress-induced changes in gene expression in Toxoplasma. In contrast to other lower eukaryotes, Toxoplasma has duplicated its GCN5 lysine acetyltransferase (KAT). Disruption of the gene encoding for TgGCN5-A in type I RH strain did not produce a severe phenotype under normal culture conditions, but here we show that the TgGCN5-A null mutant is deficient in responding to alkaline pH, a common stress used to induce bradyzoite differentiation in vitro. We performed a genome-wide analysis of the Toxoplasma transcriptional response to alkaline pH stress, finding that parasites deleted for TgGCN5-A fail to up-regulate 74% of the stress response genes that are induced 2-fold or more in wild-type. Using chromatin immunoprecipitation, we verify an enrichment of TgGCN5-A at the upstream regions of genes activated by alkaline pH exposure. The TgGCN5-A knockout is also incapable of up-regulating key marker genes expressed during development of the latent cyst form, and is impaired in its ability to recover from alkaline stress. Complementation of the TgGCN5-A knockout restores the expression of these stress-induced genes and reverses the stress recovery defect. These results establish TgGCN5-A as a major contributor to the alkaline stress response in RH strain Toxoplasma.
PMID: 21179246
Evaluation of three novel azasterols against Toxoplasma gondii
Vet Parasitol. 2010 Dec 1. [Epub ahead of print]
Evaluation of three novel azasterols against Toxoplasma gondii
Martins-Duarte ES, Lemgruber L, Lorente SO, Gros L, Magaraci F, Gilbert IH, de Souza W, Vommaro RC.
Laboratório de Ultraestrutura Celular Herth, Meyer, Instituto de Biofísica Carlos Chagas Filho, UFRJ, CCS, Bloco G, Av. Carlo, Chagas Filho, Cidade Universitária, Ilha do Fundão, 21941-902, Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Rio de Janeiro, Brazil.
Abstract
Previous studies from our group have demonstrated the high susceptibility of Toxoplasma gondii tachyzoites to the sterol analogues 22,26-azasterol and 24,25-(R,S)-epiminolanosterol. In this work we present data on testing in vitro three novel azasterols as potential agents for the treatment of toxoplasmosis. The three compounds inhibited parasite growth at micromolar concentrations, in a dose-dependent manner. Electron microscopy analysis of intracellular tachyzoites after treatment with the most effective compound showed drastic mitochondrion swelling associated with the appearance of an electron-lucent matrix and disrupted cristae. Parasite lysis also took place. The appearance of electron dense cytoplasmic structures similar to amylopectin granules distributed throughout the parasite suggests that azasterols might be inducing differentiation of those tachyzoites which were not lysed to the bradyzoite stage.
Copyright © 2010 Elsevier B.V. All rights reserved.
PMID: 21176865
Evaluation of three novel azasterols against Toxoplasma gondii
Martins-Duarte ES, Lemgruber L, Lorente SO, Gros L, Magaraci F, Gilbert IH, de Souza W, Vommaro RC.
Laboratório de Ultraestrutura Celular Herth, Meyer, Instituto de Biofísica Carlos Chagas Filho, UFRJ, CCS, Bloco G, Av. Carlo, Chagas Filho, Cidade Universitária, Ilha do Fundão, 21941-902, Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Rio de Janeiro, Brazil.
Abstract
Previous studies from our group have demonstrated the high susceptibility of Toxoplasma gondii tachyzoites to the sterol analogues 22,26-azasterol and 24,25-(R,S)-epiminolanosterol. In this work we present data on testing in vitro three novel azasterols as potential agents for the treatment of toxoplasmosis. The three compounds inhibited parasite growth at micromolar concentrations, in a dose-dependent manner. Electron microscopy analysis of intracellular tachyzoites after treatment with the most effective compound showed drastic mitochondrion swelling associated with the appearance of an electron-lucent matrix and disrupted cristae. Parasite lysis also took place. The appearance of electron dense cytoplasmic structures similar to amylopectin granules distributed throughout the parasite suggests that azasterols might be inducing differentiation of those tachyzoites which were not lysed to the bradyzoite stage.
Copyright © 2010 Elsevier B.V. All rights reserved.
PMID: 21176865
Tuesday, December 21, 2010
Cell cycle-dependent, intercellular transmission of Toxoplasma gondii is accompanied by marked changes in parasite gene expression
Mol Microbiol. 2011 Jan;79(1):192-204. doi: 10.1111/j.1365-2958.2010.07441.x. Epub 2010 Nov 9.
Cell cycle-dependent, intercellular transmission of Toxoplasma gondii is accompanied by marked changes in parasite gene expression
Gaji RY, Behnke MS, Lehmann MM, White MW, Carruthers VB.
Department of Microbiology and Immunology, University of Michigan Medical School, 1150 W. Medical Center Dr., Ann Arbor, MI 48109, USA Department of Veterinary Molecular Biology, Montana State University, Bozeman, MT 59717, USA Departments of Molecular Medicine & Global Health, University of South Florida, Tampa, FL 33612, USA.
Abstract
Intracellular microbes have evolved efficient strategies for transitioning from one cell to another in a process termed intercellular transmission. Here we show that host cell transmission of the obligate intracellular parasite Toxoplasma gondii is closely tied to specific cell cycle distributions, with egress and reinvasion occurring most proficiently by parasites in the G1 phase. We also reveal that Toxoplasma undergoes marked changes in mRNA expression when transitioning from the extracellular environment to its intracellular niche. These mRNA level changes reflect a modal switch from expression of proteins involved in invasion, motility and signal transduction in extracellular parasites to expression of metabolic and DNA replication proteins in intracellular parasites. Host cell binding and signalling associated with the discharge of parasite secretory proteins was not sufficient to induce this switch in gene expression, suggesting that the regulatory mechanisms responsible are tied to the establishment of the intracellular environment. The genes whose expression increased after parasite invasion belong to a progressive cascade known to underlie the parasite division cycle indicating that the unique relationship between the G1 phase and invasion effectively synchronizes short-term population growth. This work provides new insight into how this highly successful parasite competently transits from cell to cell.
© 2010 Blackwell Publishing Ltd.
PMID: 21166903
Cell cycle-dependent, intercellular transmission of Toxoplasma gondii is accompanied by marked changes in parasite gene expression
Gaji RY, Behnke MS, Lehmann MM, White MW, Carruthers VB.
Department of Microbiology and Immunology, University of Michigan Medical School, 1150 W. Medical Center Dr., Ann Arbor, MI 48109, USA Department of Veterinary Molecular Biology, Montana State University, Bozeman, MT 59717, USA Departments of Molecular Medicine & Global Health, University of South Florida, Tampa, FL 33612, USA.
Abstract
Intracellular microbes have evolved efficient strategies for transitioning from one cell to another in a process termed intercellular transmission. Here we show that host cell transmission of the obligate intracellular parasite Toxoplasma gondii is closely tied to specific cell cycle distributions, with egress and reinvasion occurring most proficiently by parasites in the G1 phase. We also reveal that Toxoplasma undergoes marked changes in mRNA expression when transitioning from the extracellular environment to its intracellular niche. These mRNA level changes reflect a modal switch from expression of proteins involved in invasion, motility and signal transduction in extracellular parasites to expression of metabolic and DNA replication proteins in intracellular parasites. Host cell binding and signalling associated with the discharge of parasite secretory proteins was not sufficient to induce this switch in gene expression, suggesting that the regulatory mechanisms responsible are tied to the establishment of the intracellular environment. The genes whose expression increased after parasite invasion belong to a progressive cascade known to underlie the parasite division cycle indicating that the unique relationship between the G1 phase and invasion effectively synchronizes short-term population growth. This work provides new insight into how this highly successful parasite competently transits from cell to cell.
© 2010 Blackwell Publishing Ltd.
PMID: 21166903
Saturday, December 18, 2010
The apicoplast
Protoplasma. 2010 Dec 17. [Epub ahead of print]
The apicoplast
McFadden GI.
School of Botany, University of Melbourne, Melbourne, VIC, 3010, Australia, gim@unimelb.edu.au.
Abstract
Parasites like malaria and Toxoplasma possess a vestigial plastid homologous to the chloroplasts of plants. The plastid (known as the apicoplast) is non-photosynthetic but retains many hallmarks of its ancestry including a circular genome that it synthesises proteins from and a suite of biosynthetic pathways of cyanobacterial origin. In this review, the discovery of the apicoplast and its integration, function and purpose are explored. New insights into the apicoplast fatty acid biosynthesis pathway and some novel roles of the apicoplast in vaccine development are reviewed.
PMID: 21165662
The apicoplast
McFadden GI.
School of Botany, University of Melbourne, Melbourne, VIC, 3010, Australia, gim@unimelb.edu.au.
Abstract
Parasites like malaria and Toxoplasma possess a vestigial plastid homologous to the chloroplasts of plants. The plastid (known as the apicoplast) is non-photosynthetic but retains many hallmarks of its ancestry including a circular genome that it synthesises proteins from and a suite of biosynthetic pathways of cyanobacterial origin. In this review, the discovery of the apicoplast and its integration, function and purpose are explored. New insights into the apicoplast fatty acid biosynthesis pathway and some novel roles of the apicoplast in vaccine development are reviewed.
PMID: 21165662
Thursday, December 16, 2010
Post-genomics resources and tools for studying apicomplexan metabolism
Trends Parasitol. 2010 Dec 8. [Epub ahead of print]
Post-genomics resources and tools for studying apicomplexan metabolism
Hung SS, Parkinson J.
Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario, Canada and Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.
Abstract
The phylum Apicomplexa comprises over 5000 species of obligate intracellular parasites, many responsible for diseases that significantly impact human health and economics. To aid drug development programs, global sequencing initiatives are generating increasing numbers of apicomplexan genomes. The challenge is how best to exploit these resources to identify effective therapeutic targets. Because of its important role in growth and maintenance, much interest has centred on metabolism. However, in the absence of detailed biochemical data, reconstructing the metabolic potential from a fully sequenced genome remains problematic. In this review current resources and tools facilitating the metabolic reconstruction for apicomplexans are examined. Furthermore, how these datasets can be utilized to explore the metabolic capabilities of apicomplexans are discussed and targets for therapeutic intervention are prioritized.
Copyright © 2010 Elsevier Ltd. All rights reserved.
PMID: 21145790 [PubMed - as supplied by publisher]
Post-genomics resources and tools for studying apicomplexan metabolism
Hung SS, Parkinson J.
Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario, Canada and Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.
Abstract
The phylum Apicomplexa comprises over 5000 species of obligate intracellular parasites, many responsible for diseases that significantly impact human health and economics. To aid drug development programs, global sequencing initiatives are generating increasing numbers of apicomplexan genomes. The challenge is how best to exploit these resources to identify effective therapeutic targets. Because of its important role in growth and maintenance, much interest has centred on metabolism. However, in the absence of detailed biochemical data, reconstructing the metabolic potential from a fully sequenced genome remains problematic. In this review current resources and tools facilitating the metabolic reconstruction for apicomplexans are examined. Furthermore, how these datasets can be utilized to explore the metabolic capabilities of apicomplexans are discussed and targets for therapeutic intervention are prioritized.
Copyright © 2010 Elsevier Ltd. All rights reserved.
PMID: 21145790 [PubMed - as supplied by publisher]
Unusual anchor of a motor complex (MyoD-MLC2) to the plasma membrane of Toxoplasma gondii
Traffic. 2010 Dec 9. doi: 10.1111/j.1600-0854.2010.01148.x. [Epub ahead of print]
Unusual anchor of a motor complex (MyoD-MLC2) to the plasma membrane of Toxoplasma gondii
Polonais V, Foth BJ, Chinthalapudi K, Marq JB, Manstein DJ, Soldati-Favre D, Frénal K.
Department of Microbiology and Molecular Medicine, CMU, University of Geneva, 1 Rue Michel-Servet, CH-1211 Geneva 4, Switzerland Research Division for Structural Analysis, Hannover Medical School, OE8830, Carl-Neuberg-Strasse 1, D-30625 Hannover, Germany Institute für Biophysical Chemistry, Hannover Medical School, OE4350, Carl-Neuberg-Strasse 1, D-30625 Hannover, Germany.
Abstract
Toxoplasma gondii possesses 11 rather atypical myosin heavy chains. The only myosin light chain described to date is MLC1, associated to myosin A, and contributing to gliding motility. In this study, we examined the repertoire of calmodulin-like proteins in Apicomplexans, identified six putative myosin light chains and determined their subcellular localization in T. gondii and Plasmodium falciparum. MLC2, only found in coccidians, is associated to myosin D via its CaM-like domain and anchored to the plasma membrane of T. gondii via its N-terminal extension. Molecular modeling suggests that MyoD-MLC2 complex is more compact than the reported structure of Plasmodium MyoA-MTIP complex. Anchorage of this MLC2 to the plasma membrane is likely governed by palmitoylation.
© 2010 John Wiley & Sons A/S.
PMID: 21143563 [PubMed - as supplied by publisher]
Unusual anchor of a motor complex (MyoD-MLC2) to the plasma membrane of Toxoplasma gondii
Polonais V, Foth BJ, Chinthalapudi K, Marq JB, Manstein DJ, Soldati-Favre D, Frénal K.
Department of Microbiology and Molecular Medicine, CMU, University of Geneva, 1 Rue Michel-Servet, CH-1211 Geneva 4, Switzerland Research Division for Structural Analysis, Hannover Medical School, OE8830, Carl-Neuberg-Strasse 1, D-30625 Hannover, Germany Institute für Biophysical Chemistry, Hannover Medical School, OE4350, Carl-Neuberg-Strasse 1, D-30625 Hannover, Germany.
Abstract
Toxoplasma gondii possesses 11 rather atypical myosin heavy chains. The only myosin light chain described to date is MLC1, associated to myosin A, and contributing to gliding motility. In this study, we examined the repertoire of calmodulin-like proteins in Apicomplexans, identified six putative myosin light chains and determined their subcellular localization in T. gondii and Plasmodium falciparum. MLC2, only found in coccidians, is associated to myosin D via its CaM-like domain and anchored to the plasma membrane of T. gondii via its N-terminal extension. Molecular modeling suggests that MyoD-MLC2 complex is more compact than the reported structure of Plasmodium MyoA-MTIP complex. Anchorage of this MLC2 to the plasma membrane is likely governed by palmitoylation.
© 2010 John Wiley & Sons A/S.
PMID: 21143563 [PubMed - as supplied by publisher]
Phosphorylation of Immunity-Related GTPases by a Toxoplasma gondii-Secreted Kinase Promotes Macrophage Survival and Virulence
Cell Host Microbe. 2010 Dec 16;8(6):484-95.
Phosphorylation of Immunity-Related GTPases by a Toxoplasma gondii-Secreted Kinase Promotes Macrophage Survival and Virulence
Fentress SJ, Behnke MS, Dunay IR, Mashayekhi M, Rommereim LM, Fox BA, Bzik DJ, Taylor GA, Turk BE, Lichti CF, Townsend RR, Qiu W, Hui R, Beatty WL, Sibley LD.
Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO 63130, USA.
Abstract
Macrophages are specialized to detect and destroy intracellular microbes and yet a number of pathogens have evolved to exploit this hostile niche. Here we demonstrate that the obligate intracellular parasite Toxoplasma gondii disarms macrophage innate clearance mechanisms by secreting a serine threonine kinase called ROP18, which binds to and phosphorylates immunity-related GTPases (IRGs). Substrate profiling of ROP18 revealed a preference for a conserved motif within switch region I of the GTPase domain, a modification predicted to disrupt IRG function. Consistent with this, expression of ROP18 was both necessary and sufficient to block recruitment of Irgb6, which was in turn required for parasite destruction. ROP18 phosphorylation of IRGs prevented clearance within inflammatory monocytes and IFN-γ-activated macrophages, conferring parasite survival in vivo and promoting virulence. IRGs are implicated in clearance of a variety of intracellular pathogens, suggesting that other virulence factors may similarly thwart this innate cellular defense mechanism.
Copyright © 2010 Elsevier Inc. All rights reserved.
PMID: 21147463 [PubMed - in process]
Phosphorylation of Immunity-Related GTPases by a Toxoplasma gondii-Secreted Kinase Promotes Macrophage Survival and Virulence
Fentress SJ, Behnke MS, Dunay IR, Mashayekhi M, Rommereim LM, Fox BA, Bzik DJ, Taylor GA, Turk BE, Lichti CF, Townsend RR, Qiu W, Hui R, Beatty WL, Sibley LD.
Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO 63130, USA.
Abstract
Macrophages are specialized to detect and destroy intracellular microbes and yet a number of pathogens have evolved to exploit this hostile niche. Here we demonstrate that the obligate intracellular parasite Toxoplasma gondii disarms macrophage innate clearance mechanisms by secreting a serine threonine kinase called ROP18, which binds to and phosphorylates immunity-related GTPases (IRGs). Substrate profiling of ROP18 revealed a preference for a conserved motif within switch region I of the GTPase domain, a modification predicted to disrupt IRG function. Consistent with this, expression of ROP18 was both necessary and sufficient to block recruitment of Irgb6, which was in turn required for parasite destruction. ROP18 phosphorylation of IRGs prevented clearance within inflammatory monocytes and IFN-γ-activated macrophages, conferring parasite survival in vivo and promoting virulence. IRGs are implicated in clearance of a variety of intracellular pathogens, suggesting that other virulence factors may similarly thwart this innate cellular defense mechanism.
Copyright © 2010 Elsevier Inc. All rights reserved.
PMID: 21147463 [PubMed - in process]
Parasites paralyze cellular host defense system to promote virulence
Cell Host Microbe. 2010 Dec 16;8(6):463-4.
Parasites paralyze cellular host defense system to promote virulence
Feng CG, Sher A.
Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Abstract
To promote their survival, intracellular pathogens must confront microbicidal activities induced by interferons. In this issue of Cell Host & Microbe, Fentress et al. show that Toxoplasma gondii evades intracellular killing by deploying a virulence determinant, ROP18, which acts by directly phosphorylating and disabling an IFN-γ-inducible immunity-related GTPase involved in pathogen clearance.
Copyright © 2010 Elsevier Inc. All rights reserved.
PMID: 21147459 [PubMed - in process]
Parasites paralyze cellular host defense system to promote virulence
Feng CG, Sher A.
Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Abstract
To promote their survival, intracellular pathogens must confront microbicidal activities induced by interferons. In this issue of Cell Host & Microbe, Fentress et al. show that Toxoplasma gondii evades intracellular killing by deploying a virulence determinant, ROP18, which acts by directly phosphorylating and disabling an IFN-γ-inducible immunity-related GTPase involved in pathogen clearance.
Copyright © 2010 Elsevier Inc. All rights reserved.
PMID: 21147459 [PubMed - in process]
Acquired toxoplasmosis accompanied by facial nerve palsy in an immunocompetent 5-year-old child
J Child Neurol. 2010 Dec;25(12):1525-8.
Acquired toxoplasmosis accompanied by facial nerve palsy in an immunocompetent 5-year-old child
Galli-Tsinopoulou A, Kyrgios I, Giannopoulou EZ, Gourgoulia S, Maggana I, Katechaki E, Chatzidimitriou D, Evangeliou AE.
Department of Pediatrics, Medical School, Aristotle University, Papageorgiou General Hospital, Thessaloniki, Greece. galtsin@otenet.gr, assimina@med.auth.gr.
Abstract
Acquired toxoplasmosis, although relatively common in children, is usually asymptomatic but can also be clinically manifested by a benign and self-limited infectious mononucleosis-like syndrome. Neurological complications are very rare in immunocompetent children. The authors report a 5-year-old boy who presented with cervical lymphadenopathy because of acquired toxoplasmosis accompanied with unilateral facial nerve paralysis. Toxoplasma gondii DNA detection in blood by polymerase chain reaction, as well as elevated specific immunoglobulin M antibodies against it, established the diagnosis. Characteristic brain lesions on magnetic resonance imaging were absent and ophthalmologic examination revealed no inflammatory lesions in the retina and choroid. Treatment with pyrimethamine, sulfadiazine, and folic acid resulted in a complete recovery after 2 months of therapy. Although rare, acute facial nerve paralysis of unknown origin can be caused by acquired toxoplasmosis even in the immunocompetent pediatric population. Elevated titers of specific antibodies and the presence of parasite's DNA are key findings for the correct diagnosis.
PMID: 21148450 [PubMed - in process]
Acquired toxoplasmosis accompanied by facial nerve palsy in an immunocompetent 5-year-old child
Galli-Tsinopoulou A, Kyrgios I, Giannopoulou EZ, Gourgoulia S, Maggana I, Katechaki E, Chatzidimitriou D, Evangeliou AE.
Department of Pediatrics, Medical School, Aristotle University, Papageorgiou General Hospital, Thessaloniki, Greece. galtsin@otenet.gr, assimina@med.auth.gr.
Abstract
Acquired toxoplasmosis, although relatively common in children, is usually asymptomatic but can also be clinically manifested by a benign and self-limited infectious mononucleosis-like syndrome. Neurological complications are very rare in immunocompetent children. The authors report a 5-year-old boy who presented with cervical lymphadenopathy because of acquired toxoplasmosis accompanied with unilateral facial nerve paralysis. Toxoplasma gondii DNA detection in blood by polymerase chain reaction, as well as elevated specific immunoglobulin M antibodies against it, established the diagnosis. Characteristic brain lesions on magnetic resonance imaging were absent and ophthalmologic examination revealed no inflammatory lesions in the retina and choroid. Treatment with pyrimethamine, sulfadiazine, and folic acid resulted in a complete recovery after 2 months of therapy. Although rare, acute facial nerve paralysis of unknown origin can be caused by acquired toxoplasmosis even in the immunocompetent pediatric population. Elevated titers of specific antibodies and the presence of parasite's DNA are key findings for the correct diagnosis.
PMID: 21148450 [PubMed - in process]
Differential Effects of Three Canonical Toxoplasma Strains on Gene Expression in Human Neuroepithelial Cells
Infect Immun. 2010 Dec 13. [Epub ahead of print]
Differential Effects of Three Canonical Toxoplasma Strains on Gene Expression in Human Neuroepithelial Cells
Xiao J, Jones-Brando L, Talbot CC Jr, Yolken RH.
The Stanley Division of Developmental Neurovirology, Institute for Basic Biomedical Sciences, Johns Hopkins School of Medicine, Baltimore, MD, USA.
Abstract
Strain type is one of the key factors suspected to play a role in determing the outcome of Toxoplasma infection. In this study, we examined the transcriptional profile of human neuroepithelioma cells in response to representative strains of Toxoplasma using microarray analysis to characterize the strain-specific host cell response. The study of neural cells is of interest in light of the ability of Toxoplasma to infect the brain and to establish persistent infection within the central nervous system. We found that the extent of the expression changes varied considerably among the three strains. Neuroepithelial cells infected with Toxoplasma type I exhibited the highest level of differential gene expression, whereas type II infected cells had a substantially smaller number of genes which were differentially expressed. Cells infected with type III exhibited intermediate effects on gene expression. The three strains also differed in the individual genes and gene pathways which were altered following cellular infection. For example, gene ontology (GO) analysis indicated that type I infection largely affects genes related to central nervous system while type III infection largely alters genes which affect nucleotide metabolism; type II infection does not alter expression of a clearly defined set of genes. Moreover, Ingenuity pathway analysis (IPA) suggested the three lineages differ in the ability to manipulate their host, e.g. they employ different strategies to avoid, deflect, or subvert host defense mechanisms. These observed differences may explain some of the variation in the neurobiological effects of different strains of Toxoplasma on infected individuals.
PMID: 21149591 [PubMed - as supplied by publisher]
Differential Effects of Three Canonical Toxoplasma Strains on Gene Expression in Human Neuroepithelial Cells
Xiao J, Jones-Brando L, Talbot CC Jr, Yolken RH.
The Stanley Division of Developmental Neurovirology, Institute for Basic Biomedical Sciences, Johns Hopkins School of Medicine, Baltimore, MD, USA.
Abstract
Strain type is one of the key factors suspected to play a role in determing the outcome of Toxoplasma infection. In this study, we examined the transcriptional profile of human neuroepithelioma cells in response to representative strains of Toxoplasma using microarray analysis to characterize the strain-specific host cell response. The study of neural cells is of interest in light of the ability of Toxoplasma to infect the brain and to establish persistent infection within the central nervous system. We found that the extent of the expression changes varied considerably among the three strains. Neuroepithelial cells infected with Toxoplasma type I exhibited the highest level of differential gene expression, whereas type II infected cells had a substantially smaller number of genes which were differentially expressed. Cells infected with type III exhibited intermediate effects on gene expression. The three strains also differed in the individual genes and gene pathways which were altered following cellular infection. For example, gene ontology (GO) analysis indicated that type I infection largely affects genes related to central nervous system while type III infection largely alters genes which affect nucleotide metabolism; type II infection does not alter expression of a clearly defined set of genes. Moreover, Ingenuity pathway analysis (IPA) suggested the three lineages differ in the ability to manipulate their host, e.g. they employ different strategies to avoid, deflect, or subvert host defense mechanisms. These observed differences may explain some of the variation in the neurobiological effects of different strains of Toxoplasma on infected individuals.
PMID: 21149591 [PubMed - as supplied by publisher]
Anti-inflammatory effects of resveratrol, curcumin and simvastatin in acute small intestinal inflammation
PLoS One. 2010 Dec 3;5(12):e15099.
Anti-inflammatory effects of resveratrol, curcumin and simvastatin in acute small intestinal inflammation
Bereswill S, Muñoz M, Fischer A, Plickert R, Haag LM, Otto B, Kühl AA, Loddenkemper C, Göbel UB, Heimesaat MM.
Institut für Mikrobiologie und Hygiene, Charité - Universitätsmedizin Berlin, Berlin, Germany.
Abstract
BACKGROUND: The health beneficial effects of Resveratrol, Curcumin and Simvastatin have been demonstrated in various experimental models of inflammation. We investigated the potential anti-inflammatory and immunomodulatory mechanisms of the above mentioned compounds in a murine model of hyper-acute Th1-type ileitis following peroral infection with Toxoplasma gondii.
METHODOLOGY/PRINCIPAL FINDINGS: Here we show that after peroral administration of Resveratrol, Curcumin or Simvastatin, mice were protected from ileitis development and survived the acute phase of inflammation whereas all Placebo treated controls died. In particular, Resveratrol treatment resulted in longer-term survival. Resveratrol, Curcumin or Simvastatin treated animals displayed significantly increased numbers of regulatory T cells and augmented intestinal epithelial cell proliferation/regeneration in the ileum mucosa compared to placebo control animals. In contrast, mucosal T lymphocyte and neutrophilic granulocyte numbers in treated mice were reduced. In addition, levels of the anti-inflammatory cytokine IL-10 in ileum, mesenteric lymph nodes and spleen were increased whereas pro-inflammatory cytokine expression (IL-23p19, IFN-γ, TNF-α, IL-6, MCP-1) was found to be significantly lower in the ileum of treated animals as compared to Placebo controls. Furthermore, treated animals displayed not only fewer pro-inflammatory enterobacteria and enterococci but also higher anti-inflammatory lactobacilli and bifidobacteria loads. Most importantly, treatment with all three compounds preserved intestinal barrier functions as indicated by reduced bacterial translocation rates into spleen, liver, kidney and blood.
CONCLUSION/SIGNIFICANCE: Oral treatment with Resveratrol, Curcumin or Simvastatin ameliorates acute small intestinal inflammation by down-regulating Th1-type immune responses and prevents bacterial translocation by maintaining gut barrier function. These findings provide novel and potential prophylaxis and treatment options of patients with inflammatory bowel diseases.
PMID: 21151942 [PubMed - in process]
Anti-inflammatory effects of resveratrol, curcumin and simvastatin in acute small intestinal inflammation
Bereswill S, Muñoz M, Fischer A, Plickert R, Haag LM, Otto B, Kühl AA, Loddenkemper C, Göbel UB, Heimesaat MM.
Institut für Mikrobiologie und Hygiene, Charité - Universitätsmedizin Berlin, Berlin, Germany.
Abstract
BACKGROUND: The health beneficial effects of Resveratrol, Curcumin and Simvastatin have been demonstrated in various experimental models of inflammation. We investigated the potential anti-inflammatory and immunomodulatory mechanisms of the above mentioned compounds in a murine model of hyper-acute Th1-type ileitis following peroral infection with Toxoplasma gondii.
METHODOLOGY/PRINCIPAL FINDINGS: Here we show that after peroral administration of Resveratrol, Curcumin or Simvastatin, mice were protected from ileitis development and survived the acute phase of inflammation whereas all Placebo treated controls died. In particular, Resveratrol treatment resulted in longer-term survival. Resveratrol, Curcumin or Simvastatin treated animals displayed significantly increased numbers of regulatory T cells and augmented intestinal epithelial cell proliferation/regeneration in the ileum mucosa compared to placebo control animals. In contrast, mucosal T lymphocyte and neutrophilic granulocyte numbers in treated mice were reduced. In addition, levels of the anti-inflammatory cytokine IL-10 in ileum, mesenteric lymph nodes and spleen were increased whereas pro-inflammatory cytokine expression (IL-23p19, IFN-γ, TNF-α, IL-6, MCP-1) was found to be significantly lower in the ileum of treated animals as compared to Placebo controls. Furthermore, treated animals displayed not only fewer pro-inflammatory enterobacteria and enterococci but also higher anti-inflammatory lactobacilli and bifidobacteria loads. Most importantly, treatment with all three compounds preserved intestinal barrier functions as indicated by reduced bacterial translocation rates into spleen, liver, kidney and blood.
CONCLUSION/SIGNIFICANCE: Oral treatment with Resveratrol, Curcumin or Simvastatin ameliorates acute small intestinal inflammation by down-regulating Th1-type immune responses and prevents bacterial translocation by maintaining gut barrier function. These findings provide novel and potential prophylaxis and treatment options of patients with inflammatory bowel diseases.
PMID: 21151942 [PubMed - in process]
Regulation of chemokine responses in intestinal epithelial cells by stress and Toxoplasma gondii infection
Parasite Immunol. 2011 Jan;33(1):12-24. doi: 10.1111/j.1365-3024.2010.01248.x.
Regulation of chemokine responses in intestinal epithelial cells by stress and Toxoplasma gondii infection
Gopal R, Birdsell D, Monroy FP.
Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA.
Abstract
Infection with Toxoplasma gondii induces chemokine up-regulation in several cell types. Here, we investigated the role of stress products (norepinephrine, NE) on chemokine production in mouse intestinal epithelial cells (IECs). Purified IECs were used to determine the expression levels of chemokines by real-time PCR. There was significantly increased expression in CCL2, CCL3, CCL5, CXCL2, CXCL9 and CXCL10 in IECs following peroral infection with T. gondii (INF) on day eight post-infection (PI) compared to infected mice subjected to cold-water stress (INF+CWS). In vitro studies using the MODE-K cell line showed increased chemokine mRNA and protein expression in infected but not in cells exposed to parasite antigen. Down-regulation of chemokine expression was more pronounced when active infection was used in combination with NE. Chemokine receptor expression was increased in IECs isolated from INF and decreased in the INF+CWS group. In MODE-K cells, there was decreased mRNA expression of chemokine receptors when incubated with β-adrenergic antagonists. Neither, adrenergic antagonists blocked the effect of infection on chemokine receptor expression. Cold-water stress was able to decrease expression of chemokines and their receptors in IECs in vivo and in vitro. Cold-water stress-mediated modulation of innate intestinal responses are beneficial in C57BL/6 mice during T. gondii infection.
© 2010 Blackwell Publishing Ltd.
PMID: 21155839 [PubMed - in process]
Regulation of chemokine responses in intestinal epithelial cells by stress and Toxoplasma gondii infection
Gopal R, Birdsell D, Monroy FP.
Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA.
Abstract
Infection with Toxoplasma gondii induces chemokine up-regulation in several cell types. Here, we investigated the role of stress products (norepinephrine, NE) on chemokine production in mouse intestinal epithelial cells (IECs). Purified IECs were used to determine the expression levels of chemokines by real-time PCR. There was significantly increased expression in CCL2, CCL3, CCL5, CXCL2, CXCL9 and CXCL10 in IECs following peroral infection with T. gondii (INF) on day eight post-infection (PI) compared to infected mice subjected to cold-water stress (INF+CWS). In vitro studies using the MODE-K cell line showed increased chemokine mRNA and protein expression in infected but not in cells exposed to parasite antigen. Down-regulation of chemokine expression was more pronounced when active infection was used in combination with NE. Chemokine receptor expression was increased in IECs isolated from INF and decreased in the INF+CWS group. In MODE-K cells, there was decreased mRNA expression of chemokine receptors when incubated with β-adrenergic antagonists. Neither, adrenergic antagonists blocked the effect of infection on chemokine receptor expression. Cold-water stress was able to decrease expression of chemokines and their receptors in IECs in vivo and in vitro. Cold-water stress-mediated modulation of innate intestinal responses are beneficial in C57BL/6 mice during T. gondii infection.
© 2010 Blackwell Publishing Ltd.
PMID: 21155839 [PubMed - in process]
Thursday, December 09, 2010
Immunome Res. 2010 Dec 3;6(1):12. [Epub ahead of print]
Human immunome, bioinformatic analyses using HLA supermotifs and the parasite genome, binding assays, studies of human T cell responses, and immunization of HLA-A*1101 transgenic mice including novel adjuvants provide a foundation for HLA-A03 restricted CD8+T cell epitope based, adjuvanted vaccine protective against Toxoplasma gondii
Cong H, Mui EJ, Witola WH, Sidney J, Alexander J, Sette A, Maewal A, McLeod R.
Abstract
ABSTRACT:
BACKGROUND: Toxoplasmosis causes loss of life, cognitive and motor function, and sight. A vaccine is greatly needed to prevent this disease. The purpose of this study was to use an immmunosense approach to develop a foundation for development of vaccines to protect humans with the HLA-A03 supertype. Three peptides had been identified with high binding scores for HLA-A03 supertypes using bioinformatic algorhythms, high measured binding affinity for HLA-A03 supertype molecules, and ability to elicit IFN-gamma production by human HLA-A03 supertype peripheral blood CD8+ T cells from seropositive but not seronegative persons.
RESULTS: Herein, when these peptides were administered with the universal CD4+T cell epitope PADRE (AKFVAAWTLKAAA) and formulated as lipopeptides, or administered with GLA-SE either alone, or with PAM2Cys added, we found we successfully created preparations that induced IFN-gamma and reduced parasite burden in HLA-A*1101(an HLA-A03 supertype allele) transgenic mice. GLA-SE is a novel emulsified synthetic TLR4 ligand that is known to facilitate development of T Helper 1 cell (TH1) responses. Then, so our peptides would include those expressed in tachyzoites, bradyzoites and sporozoites from both Type I and II parasites, we used our approaches which had identified the initial peptides. We identified additional peptides using bioinformatics, binding affinity assays, and study of responses of HLA-A03 human cells. Lastly, we found that immunization of HLA-A*1101 transgenic mice with all the pooled peptides administered with PADRE, GLA-SE, and Pam2Cys is an effective way to elicit IFN-gamma producing CD8+ splenic T cells and protection. Immunizations included the following peptides together: KSFKDILPK (SAG1224-232); AMLTAFFLR (GRA6164-172); RSFKDLLKK (GRA7134-142); STFWPCLLR (SAG2C13-21); SSAYVFSVK(SPA250-258); and AVVSLLRLLK(SPA89-98). This immunization elicited robust protection, measured as reduced parasite burden using a luciferase transfected parasite, luciferin, this novel, HLA transgenic mouse model, and imaging with a Xenogen camera.
CONCLUSIONS: Toxoplasma gondii peptides elicit HLA-A03 restricted, IFN-gamma producing, CD8+ T cells in humans and mice. These peptides administered with adjuvants reduce parasite burden in HLA-A*1101 transgenic mice. This work provides a foundation for immunosense based vaccines. It also defines novel adjuvants for newly identified peptides for vaccines to prevent toxoplasmosis in those with HLA-A03 supertype alleles.
PMID: 21129215 [PubMed - as supplied by publisher]
Human immunome, bioinformatic analyses using HLA supermotifs and the parasite genome, binding assays, studies of human T cell responses, and immunization of HLA-A*1101 transgenic mice including novel adjuvants provide a foundation for HLA-A03 restricted CD8+T cell epitope based, adjuvanted vaccine protective against Toxoplasma gondii
Cong H, Mui EJ, Witola WH, Sidney J, Alexander J, Sette A, Maewal A, McLeod R.
Abstract
ABSTRACT:
BACKGROUND: Toxoplasmosis causes loss of life, cognitive and motor function, and sight. A vaccine is greatly needed to prevent this disease. The purpose of this study was to use an immmunosense approach to develop a foundation for development of vaccines to protect humans with the HLA-A03 supertype. Three peptides had been identified with high binding scores for HLA-A03 supertypes using bioinformatic algorhythms, high measured binding affinity for HLA-A03 supertype molecules, and ability to elicit IFN-gamma production by human HLA-A03 supertype peripheral blood CD8+ T cells from seropositive but not seronegative persons.
RESULTS: Herein, when these peptides were administered with the universal CD4+T cell epitope PADRE (AKFVAAWTLKAAA) and formulated as lipopeptides, or administered with GLA-SE either alone, or with PAM2Cys added, we found we successfully created preparations that induced IFN-gamma and reduced parasite burden in HLA-A*1101(an HLA-A03 supertype allele) transgenic mice. GLA-SE is a novel emulsified synthetic TLR4 ligand that is known to facilitate development of T Helper 1 cell (TH1) responses. Then, so our peptides would include those expressed in tachyzoites, bradyzoites and sporozoites from both Type I and II parasites, we used our approaches which had identified the initial peptides. We identified additional peptides using bioinformatics, binding affinity assays, and study of responses of HLA-A03 human cells. Lastly, we found that immunization of HLA-A*1101 transgenic mice with all the pooled peptides administered with PADRE, GLA-SE, and Pam2Cys is an effective way to elicit IFN-gamma producing CD8+ splenic T cells and protection. Immunizations included the following peptides together: KSFKDILPK (SAG1224-232); AMLTAFFLR (GRA6164-172); RSFKDLLKK (GRA7134-142); STFWPCLLR (SAG2C13-21); SSAYVFSVK(SPA250-258); and AVVSLLRLLK(SPA89-98). This immunization elicited robust protection, measured as reduced parasite burden using a luciferase transfected parasite, luciferin, this novel, HLA transgenic mouse model, and imaging with a Xenogen camera.
CONCLUSIONS: Toxoplasma gondii peptides elicit HLA-A03 restricted, IFN-gamma producing, CD8+ T cells in humans and mice. These peptides administered with adjuvants reduce parasite burden in HLA-A*1101 transgenic mice. This work provides a foundation for immunosense based vaccines. It also defines novel adjuvants for newly identified peptides for vaccines to prevent toxoplasmosis in those with HLA-A03 supertype alleles.
PMID: 21129215 [PubMed - as supplied by publisher]
Parasitic, fungal and prion zoonoses: An expanding universe of candidates for human disease
Clin Microbiol Infect. 2010 Dec 4. doi: 10.1111/j.1469-0691.2010.03442.x. [Epub ahead of print]
Parasitic, fungal and prion zoonoses: An expanding universe of candidates for human disease
Akritidis N.
Head, Internal Medicine Department, General Hospital "G. Hatzikosta" of Ioannina, Greece.
Abstract
Zoonotic infections have emerged as a burden for millions of people in recent years, due to re-emerging or novel pathogens often causing outbreaks in the developing world in the presence of inadequate public health infrastructure. Among zoonotic infections, parasitic pathogens are the ones that affect millions of humans worldwide, while furthermore are at risk of developing disease which is often chronic. The present review discusses the global effect of protozoan pathogens as Leishmania sp., Trypanosoma sp., and Toxoplasma sp., as well as helminthic pathogens as Echinococcus sp., Fasciola sp., and Trichinella sp. The zoonotic aspects of agents that are not essentially zoonotic are also discussed. The review further focuses on the zoonotic dynamics of fungal pathogens and prion diseases as observed in recent years, in an evolving environment that has developed novel patient target groups for agents that were previously considered obscure or of minimal significance.
Copyright © 2010 European Society of Clinical Microbiology and Infectious Diseases.
PMID: 21129103 [PubMed - as supplied by publisher]
Parasitic, fungal and prion zoonoses: An expanding universe of candidates for human disease
Akritidis N.
Head, Internal Medicine Department, General Hospital "G. Hatzikosta" of Ioannina, Greece.
Abstract
Zoonotic infections have emerged as a burden for millions of people in recent years, due to re-emerging or novel pathogens often causing outbreaks in the developing world in the presence of inadequate public health infrastructure. Among zoonotic infections, parasitic pathogens are the ones that affect millions of humans worldwide, while furthermore are at risk of developing disease which is often chronic. The present review discusses the global effect of protozoan pathogens as Leishmania sp., Trypanosoma sp., and Toxoplasma sp., as well as helminthic pathogens as Echinococcus sp., Fasciola sp., and Trichinella sp. The zoonotic aspects of agents that are not essentially zoonotic are also discussed. The review further focuses on the zoonotic dynamics of fungal pathogens and prion diseases as observed in recent years, in an evolving environment that has developed novel patient target groups for agents that were previously considered obscure or of minimal significance.
Copyright © 2010 European Society of Clinical Microbiology and Infectious Diseases.
PMID: 21129103 [PubMed - as supplied by publisher]
T cell production of matrix metalloproteases and inhibition of parasite clearance by TIMP-1 during chronic Toxoplasma infection in the brain
ASN Neuro. 2010 Dec 6. [Epub ahead of print]
T cell production of matrix metalloproteases and inhibition of parasite clearance by TIMP-1 during chronic Toxoplasma infection in the brain
Clark RT, Nance JP, Noor S, Wilson EH.
Abstract
Chronic infection with the intracellular protozoan parasite Toxoplasma gondii leads to tissue remodeling in the brain and a continuous requirement for peripheral leukocyte migration within the CNS. In this study we investigated the role of matrix metalloproteases (MMPs) and their inhibitors for T cell migration into the infected brain. Increased expression of two key molecules, MMP-8 and MMP-10, along with their inhibitor, Tissue Inhibitor of Metalloproteinases-1 (TIMP-1) was observed in the CNS following infection. Analysis of infiltrating lymphocytes demonstrated MMP-8 and -10 production by CD4+ and CD8+ T cells. In addition, infiltrating T cells and CNS resident astrocytes increased their expression of TIMP-1 following infection. TIMP-1 deficient mice had a decrease in perivascular accumulation of lymphocyte populations yet an increase in the proportion of CD4+ T cells that had trafficked into the CNS. This was accompanied by a reduction in parasite burden in the brain. Together, these findings demonstrate a role for MMPs and TIMP-1 in the trafficking of lymphocytes into the CNS during chronic infection in the brain.
PMID: 21133852 [PubMed - as supplied by publisher]Free Article
T cell production of matrix metalloproteases and inhibition of parasite clearance by TIMP-1 during chronic Toxoplasma infection in the brain
Clark RT, Nance JP, Noor S, Wilson EH.
Abstract
Chronic infection with the intracellular protozoan parasite Toxoplasma gondii leads to tissue remodeling in the brain and a continuous requirement for peripheral leukocyte migration within the CNS. In this study we investigated the role of matrix metalloproteases (MMPs) and their inhibitors for T cell migration into the infected brain. Increased expression of two key molecules, MMP-8 and MMP-10, along with their inhibitor, Tissue Inhibitor of Metalloproteinases-1 (TIMP-1) was observed in the CNS following infection. Analysis of infiltrating lymphocytes demonstrated MMP-8 and -10 production by CD4+ and CD8+ T cells. In addition, infiltrating T cells and CNS resident astrocytes increased their expression of TIMP-1 following infection. TIMP-1 deficient mice had a decrease in perivascular accumulation of lymphocyte populations yet an increase in the proportion of CD4+ T cells that had trafficked into the CNS. This was accompanied by a reduction in parasite burden in the brain. Together, these findings demonstrate a role for MMPs and TIMP-1 in the trafficking of lymphocytes into the CNS during chronic infection in the brain.
PMID: 21133852 [PubMed - as supplied by publisher]Free Article
Saturday, December 04, 2010
Impact of protozoan cell death on parasite-host interactions and pathogenesis
Parasit Vectors. 2010 Dec 2;3(1):116. [Epub ahead of print]
Impact of protozoan cell death on parasite-host interactions and pathogenesis
Luder CG, Campos-Salinas J, Gonzalez-Rey E, van Zandbergen G.
Abstract
ABSTRACT: PCD in protozoan parasites has emerged as a fascinating field of parasite biology. This not only relates to the underlying mechanisms and their evolutionary implications but also to the impact on the parasite-host interactions within mammalian hosts and arthropod vectors. During recent years, common functions of apoptosis and autophagy in protozoa and during parasitic infections have emerged. Here, we review how distinct cell death pathways in Trypanosoma, Leishmania, Plasmodium or Toxoplasma may contribute to regulation of parasite cell densities in vectors and mammalian hosts, to differentiation of parasites, to stress responses, and to modulation of the host immunity. The examples provided indicate crucial roles of PCD in parasite biology. The existence of PCD pathways in these organisms and the identification as being critical for parasite biology and parasite-host interactions could serve as a basis for developing new anti-parasitic drugs that take advantage of these pathways.
PMID: 21126352 [PubMed - as supplied by publisher]
Impact of protozoan cell death on parasite-host interactions and pathogenesis
Luder CG, Campos-Salinas J, Gonzalez-Rey E, van Zandbergen G.
Abstract
ABSTRACT: PCD in protozoan parasites has emerged as a fascinating field of parasite biology. This not only relates to the underlying mechanisms and their evolutionary implications but also to the impact on the parasite-host interactions within mammalian hosts and arthropod vectors. During recent years, common functions of apoptosis and autophagy in protozoa and during parasitic infections have emerged. Here, we review how distinct cell death pathways in Trypanosoma, Leishmania, Plasmodium or Toxoplasma may contribute to regulation of parasite cell densities in vectors and mammalian hosts, to differentiation of parasites, to stress responses, and to modulation of the host immunity. The examples provided indicate crucial roles of PCD in parasite biology. The existence of PCD pathways in these organisms and the identification as being critical for parasite biology and parasite-host interactions could serve as a basis for developing new anti-parasitic drugs that take advantage of these pathways.
PMID: 21126352 [PubMed - as supplied by publisher]
Ciliate pellicular proteome identifies novel protein families with characteristic repeat motifs that are common to Alveolates
Mol Biol Evol. 2010 Dec 2. [Epub ahead of print]
Ciliate pellicular proteome identifies novel protein families with characteristic repeat motifs that are common to Alveolates
Gould SB, Kraft LG, van Dooren GG, Goodman CD, Ford KL, Cassin AM, Bacic A, McFadden GI, Waller RF.
School of Botany, University of Melbourne, 3010 Victoria, Australia.
Abstract
The pellicles of alveolates (ciliates, apicomplexans and dinoflagellates) share a common organization, yet perform very divergent functions including motility, host cell invasion and armor. The alveolate pellicle consists of a system of flattened membrane sacs (alveoli, which are the defining feature of the group) below the plasma-membrane that is supported by a membrane skeleton as well as a network of microtubules and other filamentous elements. We recently showed that a family of proteins, alveolins, are common and unique to this pellicular structure in alveolates. To identify additional proteins that contribute to this structure, a pellicle proteome study was conducted for the ciliate Tetrahymena thermophila. We found 1173 proteins associated with this structure, 45% (529 proteins) of which represented novel proteins without matches to other functionally characterized proteins. Expression of four newly identified T. thermophila pellicular proteins as GFP-fusion proteins confirmed pellicular location, and one new protein located in the oral apparatus. Bioinformatic analysis revealed that 21% of the putative pellicular proteins, predominantly the novel proteins, contained highly repetitive regions with strong amino acid biases for particular residues (K, E, Q, L, I & V). When the T. thermophila novel proteins were compared to apicomplexan genomic data, 278 proteins with high sequence similarity were identified, suggesting that many of these putative pellicular components are shared between the alveolates. Of these shared proteins, 126 contained the distinctive repeat regions. Localization of two such proteins in Toxoplasma gondii confirmed their role in the pellicle, and in doing so identified two new proteins of the apicomplexan invasive structure - the apical complex. Screening broadly for these repetitive domains in genomic data revealed large and actively evolving families of such proteins in alveolates, suggesting that these proteins might underpin the diversity and utility of their unique pellicular structure.
PMID: 21127172 [PubMed - as supplied by publisher]
Ciliate pellicular proteome identifies novel protein families with characteristic repeat motifs that are common to Alveolates
Gould SB, Kraft LG, van Dooren GG, Goodman CD, Ford KL, Cassin AM, Bacic A, McFadden GI, Waller RF.
School of Botany, University of Melbourne, 3010 Victoria, Australia.
Abstract
The pellicles of alveolates (ciliates, apicomplexans and dinoflagellates) share a common organization, yet perform very divergent functions including motility, host cell invasion and armor. The alveolate pellicle consists of a system of flattened membrane sacs (alveoli, which are the defining feature of the group) below the plasma-membrane that is supported by a membrane skeleton as well as a network of microtubules and other filamentous elements. We recently showed that a family of proteins, alveolins, are common and unique to this pellicular structure in alveolates. To identify additional proteins that contribute to this structure, a pellicle proteome study was conducted for the ciliate Tetrahymena thermophila. We found 1173 proteins associated with this structure, 45% (529 proteins) of which represented novel proteins without matches to other functionally characterized proteins. Expression of four newly identified T. thermophila pellicular proteins as GFP-fusion proteins confirmed pellicular location, and one new protein located in the oral apparatus. Bioinformatic analysis revealed that 21% of the putative pellicular proteins, predominantly the novel proteins, contained highly repetitive regions with strong amino acid biases for particular residues (K, E, Q, L, I & V). When the T. thermophila novel proteins were compared to apicomplexan genomic data, 278 proteins with high sequence similarity were identified, suggesting that many of these putative pellicular components are shared between the alveolates. Of these shared proteins, 126 contained the distinctive repeat regions. Localization of two such proteins in Toxoplasma gondii confirmed their role in the pellicle, and in doing so identified two new proteins of the apicomplexan invasive structure - the apical complex. Screening broadly for these repetitive domains in genomic data revealed large and actively evolving families of such proteins in alveolates, suggesting that these proteins might underpin the diversity and utility of their unique pellicular structure.
PMID: 21127172 [PubMed - as supplied by publisher]
Friday, December 03, 2010
T. gondii RP Promoters & Knockdown Reveal Molecular Pathways Associated with Proliferation and Cell-Cycle Arrest
PLoS One. 2010 Nov 22;5(11):e14057.
T. gondii RP Promoters & Knockdown Reveal Molecular Pathways Associated with Proliferation and Cell-Cycle Arrest
Hutson SL, Mui E, Kinsley K, Witola WH, Behnke MS, El Bissati K, Muench SP, Rohrman B, Liu SR, Wollmann R, Ogata Y, Sarkeshik A, Yates JR, McLeod R.
Department of Surgery (Ophthalmology), The University of Chicago, Chicago, Illinois, United States of America.
Abstract
Molecular pathways regulating rapid proliferation and persistence are fundamental for pathogens but are not elucidated fully in Toxoplasma gondii. Promoters of T. gondii ribosomal proteins (RPs) were analyzed by EMSAs and ChIP. One RP promoter domain, known to bind an Apetela 2, bound to nuclear extract proteins. Promoter domains appeared to associate with histone acetyl transferases. To study effects of a RP gene's regulation in T. gondii, mutant parasites (Δrps13) were engineered with integration of tetracycline repressor (TetR) response elements in a critical location in the rps13 promoter and transfection of a yellow fluorescent-tetracycline repressor (YFP-TetR). This permitted conditional knockdown of rps13 expression in a tightly regulated manner. Δrps13 parasites were studied in the presence (+ATc) or absence of anhydrotetracycline (-ATc) in culture. -ATc, transcription of the rps13 gene and expression of RPS13 protein were markedly diminished, with concomitant cessation of parasite replication. Study of Δrps13 expressing Myc-tagged RPL22, -ATc, showed RPL22 diminished but at a slower rate. Quantitation of RNA showed diminution of 18S RNA. Depletion of RPS13 caused arrest of parasites in the G1 cell cycle phase, thereby stopping parasite proliferation. Transcriptional differences ±ATc implicate molecules likely to function in regulation of these processes. In vitro, -ATc, Δrps13 persists for months and the proliferation phenotype can be rescued with ATc. In vivo, however, Δrps13 could only be rescued when ATc was given simultaneously and not at any time after 1 week, even when L-NAME and ATc were administered. Immunization with Δrps13 parasites protects mice completely against subsequent challenge with wildtype clonal Type 1 parasites, and robustly protects mice against wildtype clonal Type 2 parasites. Our results demonstrate that G1 arrest by ribosomal protein depletion is associated with persistence of T. gondii in a model system in vitro and immunization with Δrps13 protects mice against subsequent challenge with wildtype parasites.
PMID: 21124925 [PubMed - as supplied by publisher]
T. gondii RP Promoters & Knockdown Reveal Molecular Pathways Associated with Proliferation and Cell-Cycle Arrest
Hutson SL, Mui E, Kinsley K, Witola WH, Behnke MS, El Bissati K, Muench SP, Rohrman B, Liu SR, Wollmann R, Ogata Y, Sarkeshik A, Yates JR, McLeod R.
Department of Surgery (Ophthalmology), The University of Chicago, Chicago, Illinois, United States of America.
Abstract
Molecular pathways regulating rapid proliferation and persistence are fundamental for pathogens but are not elucidated fully in Toxoplasma gondii. Promoters of T. gondii ribosomal proteins (RPs) were analyzed by EMSAs and ChIP. One RP promoter domain, known to bind an Apetela 2, bound to nuclear extract proteins. Promoter domains appeared to associate with histone acetyl transferases. To study effects of a RP gene's regulation in T. gondii, mutant parasites (Δrps13) were engineered with integration of tetracycline repressor (TetR) response elements in a critical location in the rps13 promoter and transfection of a yellow fluorescent-tetracycline repressor (YFP-TetR). This permitted conditional knockdown of rps13 expression in a tightly regulated manner. Δrps13 parasites were studied in the presence (+ATc) or absence of anhydrotetracycline (-ATc) in culture. -ATc, transcription of the rps13 gene and expression of RPS13 protein were markedly diminished, with concomitant cessation of parasite replication. Study of Δrps13 expressing Myc-tagged RPL22, -ATc, showed RPL22 diminished but at a slower rate. Quantitation of RNA showed diminution of 18S RNA. Depletion of RPS13 caused arrest of parasites in the G1 cell cycle phase, thereby stopping parasite proliferation. Transcriptional differences ±ATc implicate molecules likely to function in regulation of these processes. In vitro, -ATc, Δrps13 persists for months and the proliferation phenotype can be rescued with ATc. In vivo, however, Δrps13 could only be rescued when ATc was given simultaneously and not at any time after 1 week, even when L-NAME and ATc were administered. Immunization with Δrps13 parasites protects mice completely against subsequent challenge with wildtype clonal Type 1 parasites, and robustly protects mice against wildtype clonal Type 2 parasites. Our results demonstrate that G1 arrest by ribosomal protein depletion is associated with persistence of T. gondii in a model system in vitro and immunization with Δrps13 protects mice against subsequent challenge with wildtype parasites.
PMID: 21124925 [PubMed - as supplied by publisher]
Thursday, December 02, 2010
Brain parasites and suicide
Psychol Rep. 2010 Oct;107(2):424.
Brain parasites and suicide
Lester D.
Psychology Program, The Richard Stockton College of New Jersey, Jimmie Leeds Road, Pomona, NJ 08240-0195, USA. lesterd@stockton.edu
Abstract
In a sample of 20 European nations, the prevalence of the brain parasite Toxoplasma gondii was positively associated with national suicide rates for men and women.
PMID: 21117467 [PubMed - in process]
Brain parasites and suicide
Lester D.
Psychology Program, The Richard Stockton College of New Jersey, Jimmie Leeds Road, Pomona, NJ 08240-0195, USA. lesterd@stockton.edu
Abstract
In a sample of 20 European nations, the prevalence of the brain parasite Toxoplasma gondii was positively associated with national suicide rates for men and women.
PMID: 21117467 [PubMed - in process]
Role of the NF-{kappa}B transcription factor c-Rel in the generation of CD8+ T-cell responses to Toxoplasma gondii
Int Immunol. 2010 Nov;22(11):851-61.
Role of the NF-{kappa}B transcription factor c-Rel in the generation of CD8+ T-cell responses to Toxoplasma gondii
Jordan KA, Dupont CD, Tait ED, Liou HC, Hunter CA.
Department of Pathobiology, University of Pennsylvania, 380 South University Avenue, Philadelphia, PA 19104, USA.
Abstract
The nuclear factor κB transcription factor c-Rel is exclusively expressed in immune cells and plays a role in numerous cellular functions including proliferation, survival and production of chemokines and cytokines. c-Rel has also been implicated in the regulation of multiple genes involved in innate and adaptive immune responses to the intracellular protozoan parasite Toxoplasma gondii, in particular IL-12. To better understand how this transcription factor controls the CD8(+) T-cell response to this organism, wild-type (WT) and c-Rel(-/-) mice were challenged with a replication-deficient strain of T. gondii that expresses the model antigen ovalbumin (OVA). These studies revealed that c-Rel was required for optimal primary expansion of OVA-specific CD8(+) T cells and that immunized c-Rel-deficient mice were susceptible to challenge with a virulent strain of T. gondii. However, when c-Rel(-/-) cells specific for OVA were adoptively transferred into a WT recipient, or c-Rel(-/-) mice were treated with IL-12 at the time of immunization, there was no apparent proliferative defect. Surprisingly, upon secondary challenge, antigen-specific CD8(+) T cells in c-Rel(-/-) mice expanded to a much greater degree in terms of frequency as well as numbers when compared with WT mice. Despite this, the cytokine responses of c-Rel(-/-) mice remained defective, consistent with their susceptibility to secondary challenge. Together, these results indicate that in this infection model, the major influence of c-Rel in generation of CD8(+) T-cell responses is through its regulation of the inflammatory environment, rather than playing a substantial T-cell-intrinsic role.
PMID: 21118906 [PubMed - in process]
Role of the NF-{kappa}B transcription factor c-Rel in the generation of CD8+ T-cell responses to Toxoplasma gondii
Jordan KA, Dupont CD, Tait ED, Liou HC, Hunter CA.
Department of Pathobiology, University of Pennsylvania, 380 South University Avenue, Philadelphia, PA 19104, USA.
Abstract
The nuclear factor κB transcription factor c-Rel is exclusively expressed in immune cells and plays a role in numerous cellular functions including proliferation, survival and production of chemokines and cytokines. c-Rel has also been implicated in the regulation of multiple genes involved in innate and adaptive immune responses to the intracellular protozoan parasite Toxoplasma gondii, in particular IL-12. To better understand how this transcription factor controls the CD8(+) T-cell response to this organism, wild-type (WT) and c-Rel(-/-) mice were challenged with a replication-deficient strain of T. gondii that expresses the model antigen ovalbumin (OVA). These studies revealed that c-Rel was required for optimal primary expansion of OVA-specific CD8(+) T cells and that immunized c-Rel-deficient mice were susceptible to challenge with a virulent strain of T. gondii. However, when c-Rel(-/-) cells specific for OVA were adoptively transferred into a WT recipient, or c-Rel(-/-) mice were treated with IL-12 at the time of immunization, there was no apparent proliferative defect. Surprisingly, upon secondary challenge, antigen-specific CD8(+) T cells in c-Rel(-/-) mice expanded to a much greater degree in terms of frequency as well as numbers when compared with WT mice. Despite this, the cytokine responses of c-Rel(-/-) mice remained defective, consistent with their susceptibility to secondary challenge. Together, these results indicate that in this infection model, the major influence of c-Rel in generation of CD8(+) T-cell responses is through its regulation of the inflammatory environment, rather than playing a substantial T-cell-intrinsic role.
PMID: 21118906 [PubMed - in process]
Discovery of Potent and Selective Inhibitors of Calcium-Dependent Protein Kinase 1 (CDPK1) from C. parvum and T. gondii
ACS Med Chem Lett. 2010 Oct 14;1(7):331-335.
Discovery of Potent and Selective Inhibitors of Calcium-Dependent Protein Kinase 1 (CDPK1) from C. parvum and T. gondii
Murphy RC, Ojo KK, Larson ET, Castellanos-Gonzalez A, Perera BG, Keyloun KR, Kim JE, Bhandari JG, Muller NR, Verlinde CL, White AC, Merritt EA, Van Voorhis WC, Maly DJ.
Department of Chemistry, University of Washington.
Abstract
The protozoans Cryptosporidium parvum and Toxoplasma gondii are parasites of major health concern to humans. Both parasites contain a group of calcium-dependent protein kinases (CDPKs), which are found in plants and ciliates but not in humans or fungi. Here we describe a series of potent inhibitors that target CDPK1 in C. parvum (CpCDPK1) and T. gondii (TgCDPK1). These inhibitors are highly selective for CpCDPK1 and TgCDPK1 over the mammalian kinases SRC and ABL. Furthermore, they are able to block an early stage of C. parvum invasion of HCT-8 host cells, which is similar to their effects on T. gondii invasion of human fibroblasts.
PMID: 21116453 [PubMed]
Discovery of Potent and Selective Inhibitors of Calcium-Dependent Protein Kinase 1 (CDPK1) from C. parvum and T. gondii
Murphy RC, Ojo KK, Larson ET, Castellanos-Gonzalez A, Perera BG, Keyloun KR, Kim JE, Bhandari JG, Muller NR, Verlinde CL, White AC, Merritt EA, Van Voorhis WC, Maly DJ.
Department of Chemistry, University of Washington.
Abstract
The protozoans Cryptosporidium parvum and Toxoplasma gondii are parasites of major health concern to humans. Both parasites contain a group of calcium-dependent protein kinases (CDPKs), which are found in plants and ciliates but not in humans or fungi. Here we describe a series of potent inhibitors that target CDPK1 in C. parvum (CpCDPK1) and T. gondii (TgCDPK1). These inhibitors are highly selective for CpCDPK1 and TgCDPK1 over the mammalian kinases SRC and ABL. Furthermore, they are able to block an early stage of C. parvum invasion of HCT-8 host cells, which is similar to their effects on T. gondii invasion of human fibroblasts.
PMID: 21116453 [PubMed]
Saturday, November 27, 2010
The antibiotic monensin causes cell cycle disruption of Toxoplasma gondii, mediated through the DNA repair enzyme TgMSH-1
Antimicrob Agents Chemother. 2010 Nov 22. [Epub ahead of print]
The antibiotic monensin causes cell cycle disruption of Toxoplasma gondii, mediated through the DNA repair enzyme TgMSH-1
Lavine MD, Arrizabalaga G.
Department of Microbiology, Molecular Biology and Biochemistry, University of Idaho, Life Sciences South Room 142, Moscow, ID 83843, USA.
Abstract
Monensin is a polyether ionophore antibiotic that is widely used in the control of coccidia in animals. Despite its significance in veterinary medicine, little is known about its mode of action and potential mechanisms of resistance in coccidian parasites. Here we show that monensin causes accumulation of the coccidian Toxoplasma gondii at an apparent late S-phase cell cycle checkpoint. In addition, experiments utilizing a monensin-resistant T. gondii mutant show that this effect of monensin is dependent on the function of a mitochondrial homologue of the Mut-S DNA damage repair enzyme (TgMSH-1). Furthermore, the same TgMSH-1 dependent cell cycle disruption is observed with the anti-parasitic ionophore salinomycin and the DNA alkylating agent methyl nitrosourea. Our results suggest a novel mechanism for the mode of action of monensin and salynomicin on coccidial parasites, in which the drug activates a MSH-1 dependent cell cycle checkpoint by an unknown mechanism, ultimately leading to the death of the parasite. This model would indicate that cell cycle disruption is an important mediator of drug susceptibility and resistance to ionophoric antibiotics in coccidian parasites.
PMID: 21098240 [PubMed - as supplied by publisher]
The antibiotic monensin causes cell cycle disruption of Toxoplasma gondii, mediated through the DNA repair enzyme TgMSH-1
Lavine MD, Arrizabalaga G.
Department of Microbiology, Molecular Biology and Biochemistry, University of Idaho, Life Sciences South Room 142, Moscow, ID 83843, USA.
Abstract
Monensin is a polyether ionophore antibiotic that is widely used in the control of coccidia in animals. Despite its significance in veterinary medicine, little is known about its mode of action and potential mechanisms of resistance in coccidian parasites. Here we show that monensin causes accumulation of the coccidian Toxoplasma gondii at an apparent late S-phase cell cycle checkpoint. In addition, experiments utilizing a monensin-resistant T. gondii mutant show that this effect of monensin is dependent on the function of a mitochondrial homologue of the Mut-S DNA damage repair enzyme (TgMSH-1). Furthermore, the same TgMSH-1 dependent cell cycle disruption is observed with the anti-parasitic ionophore salinomycin and the DNA alkylating agent methyl nitrosourea. Our results suggest a novel mechanism for the mode of action of monensin and salynomicin on coccidial parasites, in which the drug activates a MSH-1 dependent cell cycle checkpoint by an unknown mechanism, ultimately leading to the death of the parasite. This model would indicate that cell cycle disruption is an important mediator of drug susceptibility and resistance to ionophoric antibiotics in coccidian parasites.
PMID: 21098240 [PubMed - as supplied by publisher]
Intracellular transport of Toxoplasma gondii through the blood-brain barrier
J Neuroimmunol. 2010 Nov 22. [Epub ahead of print]
Intracellular transport of Toxoplasma gondii through the blood-brain barrier
Lachenmaier SM, Deli MA, Meissner M, Liesenfeld O.
Institute of Microbiology and Hygiene, Charité-Medical School Berlin, Campus Benjamin Franklin, Berlin, Germany.
Abstract
Toxoplasma gondii establishes latent infection in the central nervous system of immunocompentent hosts. Toxoplasmic encephalitis is a life threatening reactivation of latent infection in the brain of immunocompromised patients. To further understand the mechanisms of entry into the brain of T. gondii we investigated host molecules and cells involved in the passage of the parasite through the blood-brain barrier. First, using microarrays brain endothelial cells were found to upregulate, among others, chemokines and adhesion molecules following infection with tachyzoites. Using flow cytometry we observed upregulated ICAM-1 expression on the surface of brain endothelial cells following infection; ICAM-1 expression was further increased after pre-incubation with IFN-γ. Compared to RH tachyzoites, ME49 tachyzoites induced a stronger upregulation of ICAM-1 and an earlier and stronger IL-6 and MCP-1 secretion by brain endothelial cells. Using an in vitro coculture model of the BBB (primary glia cells and brain endothelial cells) we found a stronger migration of infected antigen-presenting cells compared to lymphocytes (4.63% vs. 0.6% of all cells) across the BBB. Among all antigen-presenting cells CD11b(+)/CD11c(+) cells showed the highest infection rate, whereas the majority of infected cells that migrated through the blood-brain barrier were CD11b(+)/CD11c(-) cells. Infection of PBMCs with type I or type II Toxoplasma strains resulted in similar patterns of cell migration across the in vitro BBB model. In conclusion, these results suggest that T. gondii modulates gene expression of brain endothelial cells to promote its own migration through the blood-brain barrier in a 'Trojan horse' manner. Cells expressing CD11b either with or without CD11c are likely candidate cells for the intracellular transport of T. gondii across the BBB. T. gondii type I and type II strains induced similar migration patterns of antigen-presenting cells across the in vitro BBB.
Copyright © 2010 Elsevier B.V. All rights reserved.
PMID: 21106256 [PubMed - as supplied by publisher]
Intracellular transport of Toxoplasma gondii through the blood-brain barrier
Lachenmaier SM, Deli MA, Meissner M, Liesenfeld O.
Institute of Microbiology and Hygiene, Charité-Medical School Berlin, Campus Benjamin Franklin, Berlin, Germany.
Abstract
Toxoplasma gondii establishes latent infection in the central nervous system of immunocompentent hosts. Toxoplasmic encephalitis is a life threatening reactivation of latent infection in the brain of immunocompromised patients. To further understand the mechanisms of entry into the brain of T. gondii we investigated host molecules and cells involved in the passage of the parasite through the blood-brain barrier. First, using microarrays brain endothelial cells were found to upregulate, among others, chemokines and adhesion molecules following infection with tachyzoites. Using flow cytometry we observed upregulated ICAM-1 expression on the surface of brain endothelial cells following infection; ICAM-1 expression was further increased after pre-incubation with IFN-γ. Compared to RH tachyzoites, ME49 tachyzoites induced a stronger upregulation of ICAM-1 and an earlier and stronger IL-6 and MCP-1 secretion by brain endothelial cells. Using an in vitro coculture model of the BBB (primary glia cells and brain endothelial cells) we found a stronger migration of infected antigen-presenting cells compared to lymphocytes (4.63% vs. 0.6% of all cells) across the BBB. Among all antigen-presenting cells CD11b(+)/CD11c(+) cells showed the highest infection rate, whereas the majority of infected cells that migrated through the blood-brain barrier were CD11b(+)/CD11c(-) cells. Infection of PBMCs with type I or type II Toxoplasma strains resulted in similar patterns of cell migration across the in vitro BBB model. In conclusion, these results suggest that T. gondii modulates gene expression of brain endothelial cells to promote its own migration through the blood-brain barrier in a 'Trojan horse' manner. Cells expressing CD11b either with or without CD11c are likely candidate cells for the intracellular transport of T. gondii across the BBB. T. gondii type I and type II strains induced similar migration patterns of antigen-presenting cells across the in vitro BBB.
Copyright © 2010 Elsevier B.V. All rights reserved.
PMID: 21106256 [PubMed - as supplied by publisher]
Protective immunity induced by Toxoplasma gondii rhoptry protein 16 (ROP16) against toxoplasmosis in mice
Clin Vaccine Immunol. 2010 Nov 24. [Epub ahead of print]
Protective immunity induced by Toxoplasma gondii rhoptry protein 16 (ROP16) against toxoplasmosis in mice
Yuan ZG, Zhang XX, He XH, Petersen E, Zhou DH, He Y, Lin RQ, Li XZ, Chen XL, Shi XR, Zhong XL, Zhang B, Zhu XQ.
State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, CAAS, Lanzhou, Gansu Province 730046, PR China; Department of Parasitology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong Province 510642, PR China; College of Agriculture, South China Agricultural University, 483 Wushan Street, Tianhe District, Guangzhou, Guangdong Province 510642, PR China; Department of Infectious Diseases, Clinical Institute, and Institute of Medical Microbiology and Immunology, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark; College of Animal Science and Technology, Yunnan Agricultural University, Kunming, Yunnan Province 650201, PR China.
Abstract
Toxoplasma gondii can infect a large variety of domestic and wild animals and human beings, sometimes causing severe pathology. Rhoptries are involved in T. gondii invasion and host cell interaction, and have been implicated as important virulence factors. In this study, we constructed a DNA vaccine expressing rhoptry protein 16 (ROP16) of T. gondii, and evaluated the immune responses it induced in Kunming mice. The gene sequence encoding ROP16 was inserted into the eukaryotic expression vector pVAX I. We immunized Kunming mice intramuscularly. After immunization, we evaluated the immune response using lymphoproliferative assay, cytokine and antibody measurements, and the survival times of mice challenged lethally. The results showed that mice immunized with pVAX-ROP16 developed a high level of specific antibody responses against T. gondii ROP16 expressed in Escherichia coli, a strong lymphoproliferative response, and significant levels of IFN-γ, IL-2, IL-4 and IL-10 production, compared with other mice immunized with either empty plasmid or phosphate-buffered saline, respectively. The results showed that pVAX-ROP16 induces significant humoral and cellular Th1 immune responses. After lethal challenge, the mice immunized with the pVAX-ROP16 showed a significantly (P values < 0.05) prolonged survival time (21.6 ± 9.9 days) compared with control mice which died within 7 days of challenge. Our data demonstrate, for the first time, that ROP16 triggered a strong humoral and cellular response against T. gondii, and that ROP16 is a promising vaccine candidate against toxoplasmosis, worth further development.
PMID: 21106780 [PubMed - as supplied by publisher]
Protective immunity induced by Toxoplasma gondii rhoptry protein 16 (ROP16) against toxoplasmosis in mice
Yuan ZG, Zhang XX, He XH, Petersen E, Zhou DH, He Y, Lin RQ, Li XZ, Chen XL, Shi XR, Zhong XL, Zhang B, Zhu XQ.
State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, CAAS, Lanzhou, Gansu Province 730046, PR China; Department of Parasitology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong Province 510642, PR China; College of Agriculture, South China Agricultural University, 483 Wushan Street, Tianhe District, Guangzhou, Guangdong Province 510642, PR China; Department of Infectious Diseases, Clinical Institute, and Institute of Medical Microbiology and Immunology, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark; College of Animal Science and Technology, Yunnan Agricultural University, Kunming, Yunnan Province 650201, PR China.
Abstract
Toxoplasma gondii can infect a large variety of domestic and wild animals and human beings, sometimes causing severe pathology. Rhoptries are involved in T. gondii invasion and host cell interaction, and have been implicated as important virulence factors. In this study, we constructed a DNA vaccine expressing rhoptry protein 16 (ROP16) of T. gondii, and evaluated the immune responses it induced in Kunming mice. The gene sequence encoding ROP16 was inserted into the eukaryotic expression vector pVAX I. We immunized Kunming mice intramuscularly. After immunization, we evaluated the immune response using lymphoproliferative assay, cytokine and antibody measurements, and the survival times of mice challenged lethally. The results showed that mice immunized with pVAX-ROP16 developed a high level of specific antibody responses against T. gondii ROP16 expressed in Escherichia coli, a strong lymphoproliferative response, and significant levels of IFN-γ, IL-2, IL-4 and IL-10 production, compared with other mice immunized with either empty plasmid or phosphate-buffered saline, respectively. The results showed that pVAX-ROP16 induces significant humoral and cellular Th1 immune responses. After lethal challenge, the mice immunized with the pVAX-ROP16 showed a significantly (P values < 0.05) prolonged survival time (21.6 ± 9.9 days) compared with control mice which died within 7 days of challenge. Our data demonstrate, for the first time, that ROP16 triggered a strong humoral and cellular response against T. gondii, and that ROP16 is a promising vaccine candidate against toxoplasmosis, worth further development.
PMID: 21106780 [PubMed - as supplied by publisher]
NALP1 Influences Susceptibility to Human Congenital Toxoplasmosis, Pro-Inflammatory Cytokine Response and Fate of T. gondii-Infected Monocytic Cells
Infect Immun. 2010 Nov 22. [Epub ahead of print]
NALP1 Influences Susceptibility to Human Congenital Toxoplasmosis, Pro-Inflammatory Cytokine Response and Fate of T. gondii-Infected Monocytic Cells
Witola WH, Mui E, Hargrave A, Liu S, Hypolite M, Montpetit A, Cavailles P, Bisanz C, Cesbron-Delauw MF, Fournié GJ, McLeod R.
Departments of Surgery (Ophthalmology) and Pediatrics (Infectious Disease), The University of Chicago, Chicago, Illinois 60637, USA; Laboratoire Adaptation et Pathogénie des Micro-organismes, CNRS UMR 5163, Université Joseph Fourier GRENOBLE 1, Institut Jean Roget, BP 170, 38042 Grenoble cedex 9, France; Centre d'Innovation, Génome Québec, Montréal, Québec H3A 1A4, Canada; INSERM, U563, F-31000 Toulouse, France and University Toulouse III Paul Sabatier, F-31000 Toulouse, France.
Abstract
NALP1 is a member of the NOD-like receptor (NLR) family proteins that form inflammasomes. Upon cellular infection or stress, inflammasomes are activated, triggering maturation of pro-inflammatory cytokines and downstream cellular signaling mediated through the MyD88 adaptor. Toxoplasma gondii is an obligate intracellular parasite that stimulates production of high levels of pro-inflammatory cytokines important in innate immunity. Herein, susceptibility alleles for human congenital toxoplasmosis in NALP1 gene were identified. To investigate the role of the NALP1 inflammasome during infection with T. gondii, we genetically engineered a human monocytic cell line for NALP1 gene knockdown by RNA interference. NALP1 silencing attenuated progression of T. gondii infection, with accelerated host cell death and eventual cell disintegration. In line with this observation, up-regulation of pro-inflammatory cytokines IL-1β, IL-18 and IL-12 with T. gondii infection was not observed in monocytic cells with NALP1 knockdown. These findings suggest that the NALP1 inflammasome is critical for mediating innate immune responses to T. gondii infection and pathogenesis. Although there have been recent advances in understanding the potent activity of inflammasomes in directing innate immune responses to disease, to our knowledge, this is the first report on the crucial role of NALP1 inflammasome in the pathogenesis of T. gondii infections in humans.
PMID: 21098108 [PubMed - as supplied by publisher]
NALP1 Influences Susceptibility to Human Congenital Toxoplasmosis, Pro-Inflammatory Cytokine Response and Fate of T. gondii-Infected Monocytic Cells
Witola WH, Mui E, Hargrave A, Liu S, Hypolite M, Montpetit A, Cavailles P, Bisanz C, Cesbron-Delauw MF, Fournié GJ, McLeod R.
Departments of Surgery (Ophthalmology) and Pediatrics (Infectious Disease), The University of Chicago, Chicago, Illinois 60637, USA; Laboratoire Adaptation et Pathogénie des Micro-organismes, CNRS UMR 5163, Université Joseph Fourier GRENOBLE 1, Institut Jean Roget, BP 170, 38042 Grenoble cedex 9, France; Centre d'Innovation, Génome Québec, Montréal, Québec H3A 1A4, Canada; INSERM, U563, F-31000 Toulouse, France and University Toulouse III Paul Sabatier, F-31000 Toulouse, France.
Abstract
NALP1 is a member of the NOD-like receptor (NLR) family proteins that form inflammasomes. Upon cellular infection or stress, inflammasomes are activated, triggering maturation of pro-inflammatory cytokines and downstream cellular signaling mediated through the MyD88 adaptor. Toxoplasma gondii is an obligate intracellular parasite that stimulates production of high levels of pro-inflammatory cytokines important in innate immunity. Herein, susceptibility alleles for human congenital toxoplasmosis in NALP1 gene were identified. To investigate the role of the NALP1 inflammasome during infection with T. gondii, we genetically engineered a human monocytic cell line for NALP1 gene knockdown by RNA interference. NALP1 silencing attenuated progression of T. gondii infection, with accelerated host cell death and eventual cell disintegration. In line with this observation, up-regulation of pro-inflammatory cytokines IL-1β, IL-18 and IL-12 with T. gondii infection was not observed in monocytic cells with NALP1 knockdown. These findings suggest that the NALP1 inflammasome is critical for mediating innate immune responses to T. gondii infection and pathogenesis. Although there have been recent advances in understanding the potent activity of inflammasomes in directing innate immune responses to disease, to our knowledge, this is the first report on the crucial role of NALP1 inflammasome in the pathogenesis of T. gondii infections in humans.
PMID: 21098108 [PubMed - as supplied by publisher]
UNC93B1 is essential for TLR11 activation and IL-12 dependent host resistance to Toxoplasma gondii
J Biol Chem. 2010 Nov 19. [Epub ahead of print]
UNC93B1 is essential for TLR11 activation and IL-12 dependent host resistance to Toxoplasma gondii
Pifer R, Benson A, Sturge CR, Yarovinsky F.
University of Texas Southwestern Medical Center at Dallas, United States.
Abstract
Toll-like receptor (TLR) activation relies on biochemical recognition of microbial molecules and localization of the TLR within specific cellular compartments. Cell surface TLRs largely recognize bacterial membrane components, and intracellular TLRs are exclusively involved in sensing nucleic acids. Here we show that TLR11, an innate sensor for the Toxoplasma protein profilin, is an intracellular receptor that resides in the endoplasmic reticulum. The twelve membrane-spanning endoplasmic reticulum-resident protein UNC93B1 interacts directly with TLR11 and regulates the activation of dendritic cells (DC) in response to T. gondii profilin and parasitic infection in vivo. A deficiency in functional UNC93B1 protein abolished TLR11-dependent IL-12 secretion by DC, attenuated Th1 responses against T. gondii, and dramatically enhanced susceptibility to the parasite. Our results reveal that the association with UNC93B1 and the intracellular localization of TLRs is not a unique feature of nucleic acid-sensing TLRs but is also essential for TLR11-dependent recognition of T. gondii profilin and for host protection against this parasite.
PMID: 21097503 [PubMed - as supplied by publisher]
UNC93B1 is essential for TLR11 activation and IL-12 dependent host resistance to Toxoplasma gondii
Pifer R, Benson A, Sturge CR, Yarovinsky F.
University of Texas Southwestern Medical Center at Dallas, United States.
Abstract
Toll-like receptor (TLR) activation relies on biochemical recognition of microbial molecules and localization of the TLR within specific cellular compartments. Cell surface TLRs largely recognize bacterial membrane components, and intracellular TLRs are exclusively involved in sensing nucleic acids. Here we show that TLR11, an innate sensor for the Toxoplasma protein profilin, is an intracellular receptor that resides in the endoplasmic reticulum. The twelve membrane-spanning endoplasmic reticulum-resident protein UNC93B1 interacts directly with TLR11 and regulates the activation of dendritic cells (DC) in response to T. gondii profilin and parasitic infection in vivo. A deficiency in functional UNC93B1 protein abolished TLR11-dependent IL-12 secretion by DC, attenuated Th1 responses against T. gondii, and dramatically enhanced susceptibility to the parasite. Our results reveal that the association with UNC93B1 and the intracellular localization of TLRs is not a unique feature of nucleic acid-sensing TLRs but is also essential for TLR11-dependent recognition of T. gondii profilin and for host protection against this parasite.
PMID: 21097503 [PubMed - as supplied by publisher]
Towards an immunosense vaccine to prevent toxoplasmosis: Protective Toxoplasma gondii epitopes restricted by HLA-A*0201
Vaccine. 2010 Nov 20. [Epub ahead of print]
Towards an immunosense vaccine to prevent toxoplasmosis: Protective Toxoplasma gondii epitopes restricted by HLA-A*0201
Cong H, Mui EJ, Witola WH, Sidney J, Alexander J, Sette A, Maewal A, McLeod R.
Department of Surgery, The University of Chicago, 5841 S. Maryland Ave., MC 2114, Chicago, IL 60637, USA.
Abstract
The ideal vaccine to protect against toxoplasmosis in humans would include antigens that elicit a protective T helper cell type 1 immune response, and generate long-lived IFN-γ-producing CD8(+) T cells. Herein, we utilized a predictive algorithm to identify candidate HLA-A02 supertype epitopes from Toxoplasma gondii proteins. Thirteen peptides elicited production of IFN-γ from PBMC of HLA-A02 supertype persons seropositive for T. gondii infection but not from seronegative controls. These peptides displayed high-affinity binding to HLA-A02 proteins. Immunization of HLA-A*0201 transgenic mice with these pooled peptides, with a universal CD4(+) epitope peptide called PADRE, formulated with adjuvant GLA-SE, induced CD8(+) T cell IFN-γ production and protected against parasite challenge. Peptides identified in this study provide candidates for inclusion in immunosense epitope-based vaccines.
Copyright © 2010. Published by Elsevier Ltd.
PMID: 21095258 [PubMed - as supplied by publisher]
Towards an immunosense vaccine to prevent toxoplasmosis: Protective Toxoplasma gondii epitopes restricted by HLA-A*0201
Cong H, Mui EJ, Witola WH, Sidney J, Alexander J, Sette A, Maewal A, McLeod R.
Department of Surgery, The University of Chicago, 5841 S. Maryland Ave., MC 2114, Chicago, IL 60637, USA.
Abstract
The ideal vaccine to protect against toxoplasmosis in humans would include antigens that elicit a protective T helper cell type 1 immune response, and generate long-lived IFN-γ-producing CD8(+) T cells. Herein, we utilized a predictive algorithm to identify candidate HLA-A02 supertype epitopes from Toxoplasma gondii proteins. Thirteen peptides elicited production of IFN-γ from PBMC of HLA-A02 supertype persons seropositive for T. gondii infection but not from seronegative controls. These peptides displayed high-affinity binding to HLA-A02 proteins. Immunization of HLA-A*0201 transgenic mice with these pooled peptides, with a universal CD4(+) epitope peptide called PADRE, formulated with adjuvant GLA-SE, induced CD8(+) T cell IFN-γ production and protected against parasite challenge. Peptides identified in this study provide candidates for inclusion in immunosense epitope-based vaccines.
Copyright © 2010. Published by Elsevier Ltd.
PMID: 21095258 [PubMed - as supplied by publisher]
Evaluation of the immune response induced by DNA vaccine cocktail expressing complete SAG1 and ROP2 genes against toxoplasmosis
Vaccine. 2010 Nov 20. [Epub ahead of print]
Evaluation of the immune response induced by DNA vaccine cocktail expressing complete SAG1 and ROP2 genes against toxoplasmosis
Hoseinian Khosroshahi K, Ghaffarifar F, D'Souza S, Sharifi Z, Dalimi A.
Dept. Parasitology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
Abstract
Toxoplasma gondii, the pathogen of toxoplasmosis, can infect most mammals and birds. The high incidence and severe or lethal damages of toxoplasmosis clearly indicate the need for the development of a more effective vaccine. We constructed a DNA cocktail, containing plasmids encoding the full-length SAG1 and ROP2 genes of T. gondii and evaluated its immune response and protective efficacy in comparison with single-gene vaccines and control groups. We immunized BALB/c mice intramuscularly three times. DNA cocktail elicited IgG and IFN-γ, TNF-α and IL-2 greater than single-gene plasmids and increased survival time against a lethal challenge with the highly virulent T. gondii RH strain. The current study shows that pc-SAG1+ pc-ROP2 as a cocktail DNA vaccine produces higher Th1 immune response than single-gene plasmids and cocktail DNA is effective to prime an enhanced and balanced specific immunity.
Copyright © 2010. Published by Elsevier Ltd.
PMID: 21095254 [PubMed - as supplied by publisher]
Evaluation of the immune response induced by DNA vaccine cocktail expressing complete SAG1 and ROP2 genes against toxoplasmosis
Hoseinian Khosroshahi K, Ghaffarifar F, D'Souza S, Sharifi Z, Dalimi A.
Dept. Parasitology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
Abstract
Toxoplasma gondii, the pathogen of toxoplasmosis, can infect most mammals and birds. The high incidence and severe or lethal damages of toxoplasmosis clearly indicate the need for the development of a more effective vaccine. We constructed a DNA cocktail, containing plasmids encoding the full-length SAG1 and ROP2 genes of T. gondii and evaluated its immune response and protective efficacy in comparison with single-gene vaccines and control groups. We immunized BALB/c mice intramuscularly three times. DNA cocktail elicited IgG and IFN-γ, TNF-α and IL-2 greater than single-gene plasmids and increased survival time against a lethal challenge with the highly virulent T. gondii RH strain. The current study shows that pc-SAG1+ pc-ROP2 as a cocktail DNA vaccine produces higher Th1 immune response than single-gene plasmids and cocktail DNA is effective to prime an enhanced and balanced specific immunity.
Copyright © 2010. Published by Elsevier Ltd.
PMID: 21095254 [PubMed - as supplied by publisher]
Segmental Meningomyelitis in 2 Cats Caused by Toxoplasma gondii
J Vet Intern Med. 2010 Nov 23. doi: 10.1111/j.1939-1676.2010.0635.x. [Epub ahead of print]
Segmental Meningomyelitis in 2 Cats Caused by Toxoplasma gondii
Alves L, Gorgas D, Vandevelde M, Gandini G, Henke D.
Department of Clinical Veterinary Medicine, Division of Clinical Neurology, Vetsuisse Faculty, University of Berne, Berne, Switzerland Division of Clinical Radiology, Vetsuisse Faculty, University of Berne, Berne, Switzerland Department of Veterinary Clinics, Faculty of Veterinary Medicine, University of Bologna, Bologna, Italy.
PMID: 21092003 [PubMed - as supplied by publisher]
Segmental Meningomyelitis in 2 Cats Caused by Toxoplasma gondii
Alves L, Gorgas D, Vandevelde M, Gandini G, Henke D.
Department of Clinical Veterinary Medicine, Division of Clinical Neurology, Vetsuisse Faculty, University of Berne, Berne, Switzerland Division of Clinical Radiology, Vetsuisse Faculty, University of Berne, Berne, Switzerland Department of Veterinary Clinics, Faculty of Veterinary Medicine, University of Bologna, Bologna, Italy.
PMID: 21092003 [PubMed - as supplied by publisher]
Monday, November 22, 2010
Evaluation of three recombinant multi-antigenic vaccines composed of surface and secretory antigens of Toxoplasma gondii
Vaccine. 2010 Nov 15. [Epub ahead of print]
Evaluation of three recombinant multi-antigenic vaccines composed of surface and secretory antigens of Toxoplasma gondii in murine models of experimental toxoplasmosis
Dziadek B, Gatkowska J, Brzostek A, Dziadek J, Dzitko K, Grzybowski M, Dlugonska H.
Department of Immunoparasitology, University of Lodz, Lodz, Poland.
Abstract
The great clinical and economical impact of Toxoplasma gondii infections makes the development of an effective vaccine for controlling toxoplasmosis an extremely important aim. In the present study, we evaluate the protective and immunogenic properties of three recombinant subunit vaccines composed of rROP2+rGRA4+rSAG1, rROP2+rROP4+rGRA4 and rROP2+rROP4+rSAG1 proteins of T. gondii in an experimental toxoplasmosis model in the C3H/HeJ and C57BL/6 mouse strains. All three recombinant vaccines induced partial protection as measured by the reduction of brain cyst burden following challenge with five tissue cysts of the low virulence DX T. gondii strain. The level of protection was dependent on the antigen composition of the vaccine and the genetic background of the laboratory animals. The strongest protection against chronic toxoplasmosis was induced in both C3H/HeJ and C57BL/6 mice by the mixture of rhoptry proteins rROP2 and rROP4 combined with tachyzoite major protein SAG1. The average parasite burden in these groups of mice was reduced by 71% and 90%, respectively, compared to non-vaccinated mice. The observed protective effect was related to the vaccine-induced cellular and humoral immune responses, as measured by the antigen-induced release of the Th1 cytokines IFN-γ and IL-2, the antigen-stimulated proliferation of spleen cells of vaccinated animals in comparison to control animals and the development of systemic antigen-specific IgG1 and IgG2a (C3H/HeJ) or IgG2c (C57BL/6) antibodies. Our studies show that recombinant rROP2, rROP4, rGRA4 and rSAG1 antigens may be promising candidates for a subunit vaccine against toxoplasmosis. Additionally, we demonstrate that the ideal composition of vaccine antigens can be equally effective in mice with different genetic backgrounds and variable levels of innate resistance to toxoplasmosis, resulting in strong protection against T. gondii invasion.
Copyright © 2010. Published by Elsevier Ltd.
PMID: 21087690 [PubMed - as supplied by publisher]
Evaluation of three recombinant multi-antigenic vaccines composed of surface and secretory antigens of Toxoplasma gondii in murine models of experimental toxoplasmosis
Dziadek B, Gatkowska J, Brzostek A, Dziadek J, Dzitko K, Grzybowski M, Dlugonska H.
Department of Immunoparasitology, University of Lodz, Lodz, Poland.
Abstract
The great clinical and economical impact of Toxoplasma gondii infections makes the development of an effective vaccine for controlling toxoplasmosis an extremely important aim. In the present study, we evaluate the protective and immunogenic properties of three recombinant subunit vaccines composed of rROP2+rGRA4+rSAG1, rROP2+rROP4+rGRA4 and rROP2+rROP4+rSAG1 proteins of T. gondii in an experimental toxoplasmosis model in the C3H/HeJ and C57BL/6 mouse strains. All three recombinant vaccines induced partial protection as measured by the reduction of brain cyst burden following challenge with five tissue cysts of the low virulence DX T. gondii strain. The level of protection was dependent on the antigen composition of the vaccine and the genetic background of the laboratory animals. The strongest protection against chronic toxoplasmosis was induced in both C3H/HeJ and C57BL/6 mice by the mixture of rhoptry proteins rROP2 and rROP4 combined with tachyzoite major protein SAG1. The average parasite burden in these groups of mice was reduced by 71% and 90%, respectively, compared to non-vaccinated mice. The observed protective effect was related to the vaccine-induced cellular and humoral immune responses, as measured by the antigen-induced release of the Th1 cytokines IFN-γ and IL-2, the antigen-stimulated proliferation of spleen cells of vaccinated animals in comparison to control animals and the development of systemic antigen-specific IgG1 and IgG2a (C3H/HeJ) or IgG2c (C57BL/6) antibodies. Our studies show that recombinant rROP2, rROP4, rGRA4 and rSAG1 antigens may be promising candidates for a subunit vaccine against toxoplasmosis. Additionally, we demonstrate that the ideal composition of vaccine antigens can be equally effective in mice with different genetic backgrounds and variable levels of innate resistance to toxoplasmosis, resulting in strong protection against T. gondii invasion.
Copyright © 2010. Published by Elsevier Ltd.
PMID: 21087690 [PubMed - as supplied by publisher]
Friday, November 19, 2010
New details on the fine structure of the rhoptry of Toxoplasma gondii
Microsc Res Tech. 2010 Nov 17. [Epub ahead of print]
New details on the fine structure of the rhoptry of Toxoplasma gondii
Lemgruber L, Lupetti P, De Souza W, Vommaro RC.
Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil.
Abstract
Rhoptries are organelles that have important, complex roles in Apicomplexa biology. During Toxoplasma gondii infection, these organelles take part in several essential and complex processes that include host cell entry and parasite development. Using different electron microscopy techniques, we characterized the fine morphology of the rhoptries of two of the most important life stages of T. gondii: the tachyzoite and the bradyzoite forms. The observed tachyzoite and bradyzoite rhoptries had delimited regions characterized by a dark and electron-dense neck, an amorphous and less electron-dense bulb, and a region of intermediate electron density, which connects the bulb to the neck. Metal replicas of frozen-fractured tachyzoites showed intramembranous particles of different densities and sizes on the fractured faces of rhoptry membranes. Both in tachyzoites and bradyzoites, the intramembranous particles were arranged in distinctive parallel arrays that decorated most part of these organelles. Tubulo-vesicular subcompartments and free particles within the rhoptry lumen were observed on freeze-fractured replicas. Cryo-fixed, deep-etched samples showed several pore-like structures localized in the bulb portion. No obvious evidence was found of a possible connection between rhoptries and micronemes. Microsc. Res. Tech., 2010. © 2010 Wiley-Liss, Inc.
PMID: 21086448 [PubMed - as supplied by publisher]
New details on the fine structure of the rhoptry of Toxoplasma gondii
Lemgruber L, Lupetti P, De Souza W, Vommaro RC.
Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil.
Abstract
Rhoptries are organelles that have important, complex roles in Apicomplexa biology. During Toxoplasma gondii infection, these organelles take part in several essential and complex processes that include host cell entry and parasite development. Using different electron microscopy techniques, we characterized the fine morphology of the rhoptries of two of the most important life stages of T. gondii: the tachyzoite and the bradyzoite forms. The observed tachyzoite and bradyzoite rhoptries had delimited regions characterized by a dark and electron-dense neck, an amorphous and less electron-dense bulb, and a region of intermediate electron density, which connects the bulb to the neck. Metal replicas of frozen-fractured tachyzoites showed intramembranous particles of different densities and sizes on the fractured faces of rhoptry membranes. Both in tachyzoites and bradyzoites, the intramembranous particles were arranged in distinctive parallel arrays that decorated most part of these organelles. Tubulo-vesicular subcompartments and free particles within the rhoptry lumen were observed on freeze-fractured replicas. Cryo-fixed, deep-etched samples showed several pore-like structures localized in the bulb portion. No obvious evidence was found of a possible connection between rhoptries and micronemes. Microsc. Res. Tech., 2010. © 2010 Wiley-Liss, Inc.
PMID: 21086448 [PubMed - as supplied by publisher]
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