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
Wednesday, December 29, 2010
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]
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