Vet Parasitol. 2009 Mar 13. [Epub ahead of print]
Toxoplasmosis in sheep-The last 20 years
Dubey JP.
United States Department of Agriculture, Agricultural Research Service, Animal and Natural Resources Institute, Animal Parasitic Diseases Laboratory, Building 1001, Beltsville, MD 20705-2350, USA.
Sheep are important to the economy of many countries because they are a source of food for humans Sheep are commonly infected with the protozoan parasite, Toxoplasma gondii. Infection with the parasite may cause early embryonic death and resorption, fetal death and mummification, abortion, stillbirth, and neonatal death. Severity of infection is associated with the stage of pregnancy at which the ewe becomes infected, the earlier in gestation, the more severe the consequences. Infected sheep meat is a source of T. gondii infection for humans and carnivorous animals. Most sheep acquire T. gondii infection after birth, and less than 4% of persistently infected sheep transmit the parasite vertically to the next generation. Recent studies by a group of researchers in England reported that repeat ovine transmission of T. gondii may be more common than previously believed but these findings are soley based on PCR data and require additional data using other techniques to verify the findings. Following infection with T. gondii, sheep develop humoral and cell-mediated immune responses against the parasite that provides effective protection against disease in subsequent pregnancies. A commercial vaccine is available, comprising a live, incomplete strain of T. gondii. The vaccine is administered to sheep prior to mating to protect against lamb losses due to toxoplasmosis. In the present paper, information on the prevalence, transmission, and control of ovine toxoplasmosis in the last 20 years is reviewed.
PMID: 19395175 [PubMed - as supplied by publisher]
Wednesday, April 29, 2009
Sunday, April 26, 2009
Host cell P-glycoprotein is essential for cholesterol uptake and replication of Toxoplasma
J Biol Chem. 2009 Apr 22. [Epub ahead of print]
Host cell P-glycoprotein is essential for cholesterol uptake and replication of toxoplasma gondii
Bottova I, Hehl AB, -Tefanic SA, Fabriàs G, Casas J, Schraner E, Pieters J, Sonda S.
Institute of Parasitology, University of Zurich, Zurich 8057.
P-glycoprotein (P-gp) is a membrane-bound efflux pump which actively exports a wide range of compounds from the cell and is associated with the phenomenon of multidrug-resistance. However, the role of P-gp in normal physiological processes remains elusive. Using P-gp deficient fibroblasts, we showed that P-gp was critical for the replication of the intracellular parasite Toxoplasma gondii, but was not involved in invasion of host cells by the parasite. Importantly, we found that the protein participated in the transport of host-derived cholesterol to the intracellular parasite. T. gondii replication in P-gp deficient host cells not only resulted in reduced cholesterol content in the parasite but also altered its sphingolipid metabolism. In addition, we found that different levels of P-gp expression modified the cholesterol metabolism in uninfected fibroblasts. Collectively our findings reveal a key and previously undocumented role of P-gp in host-parasite interaction and suggest a physiological role of P-gp in cholesterol trafficking in mammalian cells.
PMID: 19389707 [PubMed - as supplied by publisher]
Host cell P-glycoprotein is essential for cholesterol uptake and replication of toxoplasma gondii
Bottova I, Hehl AB, -Tefanic SA, Fabriàs G, Casas J, Schraner E, Pieters J, Sonda S.
Institute of Parasitology, University of Zurich, Zurich 8057.
P-glycoprotein (P-gp) is a membrane-bound efflux pump which actively exports a wide range of compounds from the cell and is associated with the phenomenon of multidrug-resistance. However, the role of P-gp in normal physiological processes remains elusive. Using P-gp deficient fibroblasts, we showed that P-gp was critical for the replication of the intracellular parasite Toxoplasma gondii, but was not involved in invasion of host cells by the parasite. Importantly, we found that the protein participated in the transport of host-derived cholesterol to the intracellular parasite. T. gondii replication in P-gp deficient host cells not only resulted in reduced cholesterol content in the parasite but also altered its sphingolipid metabolism. In addition, we found that different levels of P-gp expression modified the cholesterol metabolism in uninfected fibroblasts. Collectively our findings reveal a key and previously undocumented role of P-gp in host-parasite interaction and suggest a physiological role of P-gp in cholesterol trafficking in mammalian cells.
PMID: 19389707 [PubMed - as supplied by publisher]
Toxoplasma gondii in the bone marrow after pancreas-kidney transplantation
Br J Haematol. 2009 Apr 13. [Epub ahead of print]
Toxoplasma gondii in the bone marrow after pancreas-kidney transplantation
Seguro FS, Assis RA, Silveira PA, Bezerra AM.
Department of Clinical Pathology, Hospital Israelita Albert Einstein, Sao Paulo, Brazil.
PMID: 19388940 [PubMed - as supplied by publisher]
Toxoplasma gondii in the bone marrow after pancreas-kidney transplantation
Seguro FS, Assis RA, Silveira PA, Bezerra AM.
Department of Clinical Pathology, Hospital Israelita Albert Einstein, Sao Paulo, Brazil.
PMID: 19388940 [PubMed - as supplied by publisher]
Effects of Artemisia annua L. on susceptibility to infection in experimental models
Exp Parasitol. 2009 Apr 20. [Epub ahead of print]
Toxoplasma gondii: effects of Artemisia annua L. on susceptibility to infection in experimental models in vitro and in vivo
de Oliveira TS, Oliveira Silva DA, Rostkowska C, Béla SR, Ferro EA, Magalhães PM, Mineo JR.
Laboratory of Immunoparasitology, Institute of Biomedical Sciences, Federal University of Uberlândia, Av. Pará 1720, 38400-902 Uberlândia, MG, Brazil.
Considering that the treatment for toxoplasmosis is based on drugs that show limited efficacy due to their substantial side effects, the purpose of the present study was to evaluate the effects of Artemisia annua on in vitro and in vivoToxoplasma gondii infection. A. annua infusion was prepared from dried herb and tested in human foreskin fibroblasts (HFF) or mice that were infected with the parasite and compared with sulfadiazine treatment. For in vitro experiments, treatment was done on parasite before HFF infection or on cells previously infected with T. gondii and the inhibitory concentration (IC(50)) values for each treatment condition were determined. Viability of HFF cells in the presence of different concentrations of A. annua infusion and sulfadiazine was above 72%, even when the highest concentrations from both treatments were tested. Also, the treatment of T. gondii tachyzoites with A. annua infusion before infection in HFF cells showed a dose-response inhibitory curve that reached up to 75% of inhibition, similarly to the results observed when parasites were treated with sulfadiazine. In vivo experiments with a cystogenic T. gondii strain demonstrated an effective control of infection using A. annua infusion. In conclusion, our results indicate that A. annua infusion is useful to control T. gondii infection, due to its low toxicity and its inhibitory action directly against the parasite, resulting in a well tolerated therapeutic tool.
PMID: 19389400 [PubMed - as supplied by publisher]
Toxoplasma gondii: effects of Artemisia annua L. on susceptibility to infection in experimental models in vitro and in vivo
de Oliveira TS, Oliveira Silva DA, Rostkowska C, Béla SR, Ferro EA, Magalhães PM, Mineo JR.
Laboratory of Immunoparasitology, Institute of Biomedical Sciences, Federal University of Uberlândia, Av. Pará 1720, 38400-902 Uberlândia, MG, Brazil.
Considering that the treatment for toxoplasmosis is based on drugs that show limited efficacy due to their substantial side effects, the purpose of the present study was to evaluate the effects of Artemisia annua on in vitro and in vivoToxoplasma gondii infection. A. annua infusion was prepared from dried herb and tested in human foreskin fibroblasts (HFF) or mice that were infected with the parasite and compared with sulfadiazine treatment. For in vitro experiments, treatment was done on parasite before HFF infection or on cells previously infected with T. gondii and the inhibitory concentration (IC(50)) values for each treatment condition were determined. Viability of HFF cells in the presence of different concentrations of A. annua infusion and sulfadiazine was above 72%, even when the highest concentrations from both treatments were tested. Also, the treatment of T. gondii tachyzoites with A. annua infusion before infection in HFF cells showed a dose-response inhibitory curve that reached up to 75% of inhibition, similarly to the results observed when parasites were treated with sulfadiazine. In vivo experiments with a cystogenic T. gondii strain demonstrated an effective control of infection using A. annua infusion. In conclusion, our results indicate that A. annua infusion is useful to control T. gondii infection, due to its low toxicity and its inhibitory action directly against the parasite, resulting in a well tolerated therapeutic tool.
PMID: 19389400 [PubMed - as supplied by publisher]
Wednesday, April 22, 2009
Aldolase Is Essential for Energy Production and Bridging Adhesin-Actin Cytoskeletal Interactions during Parasite Invasion of Host Cells
Cell Host Microbe. 2009 Apr 23;5(4):353-64
Aldolase Is Essential for Energy Production and Bridging Adhesin-Actin Cytoskeletal Interactions during Parasite Invasion of Host Cells
Starnes GL, Coincon M, Sygusch J, Sibley LD.
Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63130-1093, USA.
Apicomplexan parasites rely on actin-based motility to drive host cell invasion. Prior in vitro studies implicated aldolase, a tetrameric glycolytic enzyme, in coupling actin filaments to the parasite's surface adhesin microneme protein 2 (MIC2). Here, we test the essentiality of this interaction in host cell invasion. Based on in vitro studies and homology modeling, we generated a series of mutations in Toxoplasma gondii aldolase (TgALD1) that delineated MIC2 tail domain (MIC2t) binding function from its enzyme activity. We tested these mutants by complementing a conditional knockout of TgALD1. Mutations that affected glycolysis also reduced motility. Mutants only affecting binding to MIC2t had no motility phenotype, but were decreased in their efficiency of host cell invasion. Our studies demonstrate that aldolase is not only required for energy production but is also essential for efficient host cell invasion, based on its ability to bridge adhesin-cytoskeleton interactions in the parasite.
PMID: 19380114 [PubMed - in process]
Aldolase Is Essential for Energy Production and Bridging Adhesin-Actin Cytoskeletal Interactions during Parasite Invasion of Host Cells
Starnes GL, Coincon M, Sygusch J, Sibley LD.
Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63130-1093, USA.
Apicomplexan parasites rely on actin-based motility to drive host cell invasion. Prior in vitro studies implicated aldolase, a tetrameric glycolytic enzyme, in coupling actin filaments to the parasite's surface adhesin microneme protein 2 (MIC2). Here, we test the essentiality of this interaction in host cell invasion. Based on in vitro studies and homology modeling, we generated a series of mutations in Toxoplasma gondii aldolase (TgALD1) that delineated MIC2 tail domain (MIC2t) binding function from its enzyme activity. We tested these mutants by complementing a conditional knockout of TgALD1. Mutations that affected glycolysis also reduced motility. Mutants only affecting binding to MIC2t had no motility phenotype, but were decreased in their efficiency of host cell invasion. Our studies demonstrate that aldolase is not only required for energy production but is also essential for efficient host cell invasion, based on its ability to bridge adhesin-cytoskeleton interactions in the parasite.
PMID: 19380114 [PubMed - in process]
Transfection of Eimeria and Toxoplasma using heterologous regulatory sequences
Int J Parasitol. 2009 Apr 17. [Epub ahead of print]
Transfection of Eimeria and Toxoplasma using heterologous regulatory sequences
Zou J, Liu X, Shi T, Huang X, Wang H, Hao L, Yin G, Suo X.
Parasitology Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China.
Eimeriatenella and Toxoplasmagondii are Apicomplexan protozoa and share many similarities in biology and genomics. While the latter parasites are easily cultured in vitro and genetically manipulated, many Eimeria species are difficult to grow in vitro. We hypothesized that molecular tools for the genetic manipulation of T. gondii could be applied to the study of Eimeria parasites. Here we show that three different promoter sequences originating from E. tenella could function effectively not only in other species of the Eimeria genus (histone H4) but also in T. gondii (histone H4, actin and tubulin). Similarly, promoters of the "housekeeping" gene (tubulin) and differentially regulated gene (surface antigen gene, sag1) of T. gondii were effective in driving the expression of the yellow fluorescent protein (YFP) maker gene in E. tenella. The transfection efficiency with heterologous regulatory sequences was similar to that with homologous promoters; while the promoter strength of heterologous vectors is slightly weaker than the homologous vectors in both E. tenella and T. gondii. The results suggest that 5' regulatory sequences are functionally conserved not only among the Eimeria species, but also between T. gondii and E. tenella, and that T. gondii could be used as a novel transfection check system for Eimeria-rooted vectors, accelerating the development of reverse genetics in Eimeria spp.
PMID: 19379753 [PubMed - as supplied by publisher]
Transfection of Eimeria and Toxoplasma using heterologous regulatory sequences
Zou J, Liu X, Shi T, Huang X, Wang H, Hao L, Yin G, Suo X.
Parasitology Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China.
Eimeriatenella and Toxoplasmagondii are Apicomplexan protozoa and share many similarities in biology and genomics. While the latter parasites are easily cultured in vitro and genetically manipulated, many Eimeria species are difficult to grow in vitro. We hypothesized that molecular tools for the genetic manipulation of T. gondii could be applied to the study of Eimeria parasites. Here we show that three different promoter sequences originating from E. tenella could function effectively not only in other species of the Eimeria genus (histone H4) but also in T. gondii (histone H4, actin and tubulin). Similarly, promoters of the "housekeeping" gene (tubulin) and differentially regulated gene (surface antigen gene, sag1) of T. gondii were effective in driving the expression of the yellow fluorescent protein (YFP) maker gene in E. tenella. The transfection efficiency with heterologous regulatory sequences was similar to that with homologous promoters; while the promoter strength of heterologous vectors is slightly weaker than the homologous vectors in both E. tenella and T. gondii. The results suggest that 5' regulatory sequences are functionally conserved not only among the Eimeria species, but also between T. gondii and E. tenella, and that T. gondii could be used as a novel transfection check system for Eimeria-rooted vectors, accelerating the development of reverse genetics in Eimeria spp.
PMID: 19379753 [PubMed - as supplied by publisher]
Particularities of Mitochondrial Structure in Parasitic Protozoa (Apicomplexa and Kinetoplastida)
Int J Biochem Cell Biol. 2009 Apr 17. [Epub ahead of print]
Particularities of Mitochondrial Structure in Parasitic Protozoa (Apicomplexa and Kinetoplastida)
de Souza W, Attias M, Rodrigues JC.
Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, CCS-Bloco G, Ilha do Fundão, 21941-902, Rio de Janeiro-RJ, Brasil; Diretoria de Programas, Instituto Nacional de Metrologia e Qualidade Industrial-INMETRO.
Without mitochondria, eukaryotic cells would depend entirely on anaerobic glycolysis for ATP generation. This also holds true for Protists, both free-living and parasitic. Parasitic Protists include agents of human and animal diseases that have a huge impact on world populations. In the phylum Apicomplexa, several species of Plasmodium cause malaria, whereas Toxoplasma gondii is a cosmopolite parasite found on all continents. Flagellates of the order Kinetoplastida include the genera Leishmania and Trypanosoma causative agents of human leishmaniasis and (depending on the species) African trypanosomiasis and Chagas disease. Although clearly distinct in many aspects, the members of these two groups bear a single and usually well developed mitochondrion. The single mitochondrion of Apicomplexa has a dense matrix and many cristae with a circular profile. The organelle is even more peculiar in the order kinetoplastida, exhibiting a condensed network of DNA at a specific position, always close to the flagellar basal body. This arrangement is known as Kinetoplast and the name of the Order derived from it. Kinetoplastids also bear glycosomes, peroxisomes that concentrate enzymes of the glycolytic cycle. Mitochondrial volume and activity is maximum when glycosomal is low and vice versa. In both Apicomplexa and Trypanosomatids, mitochondria show particularities that are absent in other eukaryotic organisms. These peculiar features make them an attractive target for therapeutic drugs for the diseases they cause.
PMID: 19379828 [PubMed - as supplied by publisher]
Particularities of Mitochondrial Structure in Parasitic Protozoa (Apicomplexa and Kinetoplastida)
de Souza W, Attias M, Rodrigues JC.
Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, CCS-Bloco G, Ilha do Fundão, 21941-902, Rio de Janeiro-RJ, Brasil; Diretoria de Programas, Instituto Nacional de Metrologia e Qualidade Industrial-INMETRO.
Without mitochondria, eukaryotic cells would depend entirely on anaerobic glycolysis for ATP generation. This also holds true for Protists, both free-living and parasitic. Parasitic Protists include agents of human and animal diseases that have a huge impact on world populations. In the phylum Apicomplexa, several species of Plasmodium cause malaria, whereas Toxoplasma gondii is a cosmopolite parasite found on all continents. Flagellates of the order Kinetoplastida include the genera Leishmania and Trypanosoma causative agents of human leishmaniasis and (depending on the species) African trypanosomiasis and Chagas disease. Although clearly distinct in many aspects, the members of these two groups bear a single and usually well developed mitochondrion. The single mitochondrion of Apicomplexa has a dense matrix and many cristae with a circular profile. The organelle is even more peculiar in the order kinetoplastida, exhibiting a condensed network of DNA at a specific position, always close to the flagellar basal body. This arrangement is known as Kinetoplast and the name of the Order derived from it. Kinetoplastids also bear glycosomes, peroxisomes that concentrate enzymes of the glycolytic cycle. Mitochondrial volume and activity is maximum when glycosomal is low and vice versa. In both Apicomplexa and Trypanosomatids, mitochondria show particularities that are absent in other eukaryotic organisms. These peculiar features make them an attractive target for therapeutic drugs for the diseases they cause.
PMID: 19379828 [PubMed - as supplied by publisher]
Saturday, April 18, 2009
Visualization of Toxoplasma gondii stage conversion by expression of stage-specific dual fluorescent proteins
Parasitology. 2009 Apr 16:1-10. [Epub ahead of print]
Visualization of Toxoplasma gondii stage conversion by expression of stage-specific dual fluorescent proteins
Unno A, Suzuki K, Batanova T, Cha SY, Jang HK, Kitoh K, Takashima Y.
Department of Veterinary Parasitological Diseases, Gifu University, Yanagido 1-1, Gifu 501-1193, Japan.
SUMMARYTo recognize the stage conversion of Toxoplasma gondii between tachyzoite and bradyzoite in live host cells, a transgenic T. gondii line, which expressed stage-specific red and green fluorescence, was constructed. T. gondii PLK strain tachyzoites were stably transformed with genes encoding red fluorescent protein (DsRed Express) and green fluorescent protein (GFP) under the control of tachyzoite-specific SAG1 and bradyzoite-specific BAG1 promoters, respectively. The resulting transgenic parasite was designated PLK/DUAL. When PLK/DUAL was cultured in pH 7.0 medium, the PLK/DUAL zoites expressed red fluorescence, but no detectable levels of green fluorescence were observed. The PLK/DUAL zoites reacted with anti-SAG1 antibody, but not anti-BAG1 antiserum. When PLK/DUAL was cultured under high pH conditions, or in the presence of the p38 MAPK inhibitor SB202190, a small number of zoites expressed green fluorescence and were BAG1 positive. C57BL/6J mice were infected with PLK/DUAL tachyzoites. During the acute and reactivating phase, zoites expressed red fluorescence. However, green fluorescence was not detectable. By contrast, latent cysts expressed green fluorescence. The stage-specific dual fluorescence of PLK/DUAL facilitates identification of the parasitic stage in live cells, with the advantage that fixation or immunostaining is not required.
PMID: 19368740 [PubMed - as supplied by publisher]
Visualization of Toxoplasma gondii stage conversion by expression of stage-specific dual fluorescent proteins
Unno A, Suzuki K, Batanova T, Cha SY, Jang HK, Kitoh K, Takashima Y.
Department of Veterinary Parasitological Diseases, Gifu University, Yanagido 1-1, Gifu 501-1193, Japan.
SUMMARYTo recognize the stage conversion of Toxoplasma gondii between tachyzoite and bradyzoite in live host cells, a transgenic T. gondii line, which expressed stage-specific red and green fluorescence, was constructed. T. gondii PLK strain tachyzoites were stably transformed with genes encoding red fluorescent protein (DsRed Express) and green fluorescent protein (GFP) under the control of tachyzoite-specific SAG1 and bradyzoite-specific BAG1 promoters, respectively. The resulting transgenic parasite was designated PLK/DUAL. When PLK/DUAL was cultured in pH 7.0 medium, the PLK/DUAL zoites expressed red fluorescence, but no detectable levels of green fluorescence were observed. The PLK/DUAL zoites reacted with anti-SAG1 antibody, but not anti-BAG1 antiserum. When PLK/DUAL was cultured under high pH conditions, or in the presence of the p38 MAPK inhibitor SB202190, a small number of zoites expressed green fluorescence and were BAG1 positive. C57BL/6J mice were infected with PLK/DUAL tachyzoites. During the acute and reactivating phase, zoites expressed red fluorescence. However, green fluorescence was not detectable. By contrast, latent cysts expressed green fluorescence. The stage-specific dual fluorescence of PLK/DUAL facilitates identification of the parasitic stage in live cells, with the advantage that fixation or immunostaining is not required.
PMID: 19368740 [PubMed - as supplied by publisher]
Induction of partial protection against infection with Toxoplasma gondii genotype II by DNA vaccination with recombinant chimeric tachyzoite antigens
Vaccine. 2009 Apr 21;27(18):2489-98. Epub 2009 Feb 24
Induction of partial protection against infection with Toxoplasma gondii genotype II by DNA vaccination with recombinant chimeric tachyzoite antigens
Rosenberg C, De Craeye S, Jongert E, Gargano N, Beghetto E, Del Porto P, Vorup-Jensen T, Petersen E.
Department of Infectious Diseases, Aarhus University Hospital, Skejby, Denmark; Biophysical Immunology Laboratory, Institute of Medical Microbiology and Immunology, University of Aarhus, DK-8000 Aarhus C, Denmark.
Infection with the obligate intracellular parasite Toxoplasma gondii is a significant source of parasitic infections worldwide. In adults, infections may often lead to severe retinochoroiditis. Infection of the foetus causes abortion or congenital pathology that may lead to neurological complications. Although several strategies have been suggested for making a vaccine, none is currently available. Here, we investigate the protection conferred by DNA vaccination with two constructs, pcEC2 (MIC2-MIC3-SAG1) and pcEC3 (GRA3-GRA7-M2AP), encoding chimeric proteins containing multiple antigenic sequences from T. gondii. After challenge with a T. gondii genotype II, but not a genotype III strain, a significant decrease in cerebral cyst load was found compared to the controls. The immune protection involved a cell-mediated immune response with the synthesis of the cytokines IFN-? and IL-10. In silico structure analysis and the expression profile of EC2, suggest an association between antigen stability, the degree of protein secondary structure and induction of cellular immune responses. Intracellular protein degradation is an important step in the pathway leading to presentation of antigenic peptides on Major Histocompatibility Complex molecules. We suggest that degradation of this chimeric protein may have contributed to the induction of a cellular immune response via enhanced presentation of antigenic peptides on Major Histocompatibility Complex class I molecules.
PMID: 19368791 [PubMed - in process]
Induction of partial protection against infection with Toxoplasma gondii genotype II by DNA vaccination with recombinant chimeric tachyzoite antigens
Rosenberg C, De Craeye S, Jongert E, Gargano N, Beghetto E, Del Porto P, Vorup-Jensen T, Petersen E.
Department of Infectious Diseases, Aarhus University Hospital, Skejby, Denmark; Biophysical Immunology Laboratory, Institute of Medical Microbiology and Immunology, University of Aarhus, DK-8000 Aarhus C, Denmark.
Infection with the obligate intracellular parasite Toxoplasma gondii is a significant source of parasitic infections worldwide. In adults, infections may often lead to severe retinochoroiditis. Infection of the foetus causes abortion or congenital pathology that may lead to neurological complications. Although several strategies have been suggested for making a vaccine, none is currently available. Here, we investigate the protection conferred by DNA vaccination with two constructs, pcEC2 (MIC2-MIC3-SAG1) and pcEC3 (GRA3-GRA7-M2AP), encoding chimeric proteins containing multiple antigenic sequences from T. gondii. After challenge with a T. gondii genotype II, but not a genotype III strain, a significant decrease in cerebral cyst load was found compared to the controls. The immune protection involved a cell-mediated immune response with the synthesis of the cytokines IFN-? and IL-10. In silico structure analysis and the expression profile of EC2, suggest an association between antigen stability, the degree of protein secondary structure and induction of cellular immune responses. Intracellular protein degradation is an important step in the pathway leading to presentation of antigenic peptides on Major Histocompatibility Complex molecules. We suggest that degradation of this chimeric protein may have contributed to the induction of a cellular immune response via enhanced presentation of antigenic peptides on Major Histocompatibility Complex class I molecules.
PMID: 19368791 [PubMed - in process]
Friday, April 17, 2009
Protective effect of an intranasal SAG1 and MIC4 DNA vaccine in mice
Exp Parasitol. 2009 Apr 11. [Epub ahead of print]
Toxoplasma gondii: Protective effect of an intranasal SAG1 and MIC4 DNA vaccine in mice
Wang H, He S, Yao Y, Cong H, Zhao H, Li T, Zhu XQ.
Department of Parasitology, Shandong University School of Medicine, 44 Wenhua Xi Road, Jinan, Shandong Province, 250012 P.R. China.
Infections by the intracellular protozoan parasite Toxoplasma gondii are widely prevalent in humans and other animals which can cause severe or lethal toxoplasmosis. So the development of a more effective vaccine is needed urgently. A multiantigenic vaccine against toxoplasmosis was constructed in the present study, which contains two Toxoplasma gondii antigens, SAG1 and MIC4 on the basis of previous immunological and immunization studies. The eukaryotic plasmid pcDNA3.1-SAG1-MIC4, pcDNA3.1-SAG1, pcDNA3.1-MIC4 were constructed first, which can express surface protein SAG1 and microneme protein MIC4 from different stages of Toxoplasma gondii life cycle, and the expression ability of these DNA vaccine in HeLa cells were examined by Western blot. The efficacy of these plasmids with or without co-administration of a plasmid encoding cholera toxin A2/B as a genetic adjuvant by mucosal way to protect BALB/c mice against toxoplasmosis was evaluated. We found these vaccines were able to elicit a significant humoral and cellular immune response in vaccinated mice and they can increase survival rate and prolong the life of mice that were infected by T. gondii especially in the pcDNA3.1-SAG1-MIC4 group. Co-delivery of cholera toxin A2/B further enhanced the potency of multiantigenic DNA vaccine by intranasal route. These results encourage further research towards achieving vaccinal protection against the T. gondii in animals and humans.
PMID: 19366622 [PubMed - as supplied by publisher]
Toxoplasma gondii: Protective effect of an intranasal SAG1 and MIC4 DNA vaccine in mice
Wang H, He S, Yao Y, Cong H, Zhao H, Li T, Zhu XQ.
Department of Parasitology, Shandong University School of Medicine, 44 Wenhua Xi Road, Jinan, Shandong Province, 250012 P.R. China.
Infections by the intracellular protozoan parasite Toxoplasma gondii are widely prevalent in humans and other animals which can cause severe or lethal toxoplasmosis. So the development of a more effective vaccine is needed urgently. A multiantigenic vaccine against toxoplasmosis was constructed in the present study, which contains two Toxoplasma gondii antigens, SAG1 and MIC4 on the basis of previous immunological and immunization studies. The eukaryotic plasmid pcDNA3.1-SAG1-MIC4, pcDNA3.1-SAG1, pcDNA3.1-MIC4 were constructed first, which can express surface protein SAG1 and microneme protein MIC4 from different stages of Toxoplasma gondii life cycle, and the expression ability of these DNA vaccine in HeLa cells were examined by Western blot. The efficacy of these plasmids with or without co-administration of a plasmid encoding cholera toxin A2/B as a genetic adjuvant by mucosal way to protect BALB/c mice against toxoplasmosis was evaluated. We found these vaccines were able to elicit a significant humoral and cellular immune response in vaccinated mice and they can increase survival rate and prolong the life of mice that were infected by T. gondii especially in the pcDNA3.1-SAG1-MIC4 group. Co-delivery of cholera toxin A2/B further enhanced the potency of multiantigenic DNA vaccine by intranasal route. These results encourage further research towards achieving vaccinal protection against the T. gondii in animals and humans.
PMID: 19366622 [PubMed - as supplied by publisher]
The evolution of the knowledge of cat and dog coccidia
Parasitology. 2009 Apr 14:1-7. [Epub ahead of print]
The evolution of the knowledge of cat and dog coccidia
Dubey JP.
United States Department of Agriculture, Agricultural Research Service, Animal and Natural Resources Institute, Animal Parasitic Diseases Laboratory, Building 1001, Beltsville, MD 20705-2350, USA.
SUMMARYBefore the discovery of Toxoplasma gondii as a coccidium of the cat in 1970, cat and dog coccidia were classified in the genus Isospora and considered of little clinical or zoonotic significance. Since 1970, several new (Hammondia sp., Neospora sp.) and previously described species, including Sarcocystis, Besnoitia, and Cryptosporidium have been found as coccidians of cats and dogs with clinical and zoonotic significance. In the present paper I review salient features of the evolution of cat and dog coccidia.
PMID: 19366482 [PubMed - as supplied by publisher]
The evolution of the knowledge of cat and dog coccidia
Dubey JP.
United States Department of Agriculture, Agricultural Research Service, Animal and Natural Resources Institute, Animal Parasitic Diseases Laboratory, Building 1001, Beltsville, MD 20705-2350, USA.
SUMMARYBefore the discovery of Toxoplasma gondii as a coccidium of the cat in 1970, cat and dog coccidia were classified in the genus Isospora and considered of little clinical or zoonotic significance. Since 1970, several new (Hammondia sp., Neospora sp.) and previously described species, including Sarcocystis, Besnoitia, and Cryptosporidium have been found as coccidians of cats and dogs with clinical and zoonotic significance. In the present paper I review salient features of the evolution of cat and dog coccidia.
PMID: 19366482 [PubMed - as supplied by publisher]
Thursday, April 16, 2009
Porosome: the secretory portal in cells
Biochemistry. 2009 Apr 13. [Epub ahead of print]
Porosome: the secretory portal in cells
Jena BP.
Porosomes are supramolecular, cup-shaped lipoprotein structures at the cell plasma membrane, where membrane-bound secretory vesicles dock and fuse to release intravesicular contents to the outside during cell secretion. The porosome openings to the outside ranges from 150 nm in diameter in acinar cells of the exocrine pancreas to 12 nm in neurons. In the past decade the composition of the porosome, its structure and dynamics at nm resolution in real time, and its functional reconstitution into artificial lipid membrane, have been demonstrated. Discovery of the universal secretory machinery in cells -the porosome, came as no surprise since porosome-like 'canaliculi' structures for secretion from human platelets, the secretory machinery in single-cell organisms like the secretion apparatus in bacteria and Toxoplasma gondii, and the contractile vacuole in paramecium, have been demonstrated. In this review, the discovery of the porosome complex and the molecular mechanism of its function, and how this information provides a new understanding of cell secretion are discussed.
PMID: 19364126 [PubMed - as supplied by publisher]
Porosome: the secretory portal in cells
Jena BP.
Porosomes are supramolecular, cup-shaped lipoprotein structures at the cell plasma membrane, where membrane-bound secretory vesicles dock and fuse to release intravesicular contents to the outside during cell secretion. The porosome openings to the outside ranges from 150 nm in diameter in acinar cells of the exocrine pancreas to 12 nm in neurons. In the past decade the composition of the porosome, its structure and dynamics at nm resolution in real time, and its functional reconstitution into artificial lipid membrane, have been demonstrated. Discovery of the universal secretory machinery in cells -the porosome, came as no surprise since porosome-like 'canaliculi' structures for secretion from human platelets, the secretory machinery in single-cell organisms like the secretion apparatus in bacteria and Toxoplasma gondii, and the contractile vacuole in paramecium, have been demonstrated. In this review, the discovery of the porosome complex and the molecular mechanism of its function, and how this information provides a new understanding of cell secretion are discussed.
PMID: 19364126 [PubMed - as supplied by publisher]
Friday, April 10, 2009
Identification and functional characterization of cis-regulatory elements in the apicomplexan parasite Toxoplasma
Genome Biol. 2009 Apr 7;10(4):R34. [Epub ahead of print]
Identification and functional characterization of cis-regulatory elements in the apicomplexan parasite Toxoplasma gondii
Mullapudi N, Joseph S, Kissinger JC.
ABSTRACT: BACKGROUND: Toxoplasma gondii is a member of the phylum Apicomplexa; a phylum that consists entirely of parasitic organisms that cause several diseases of veterinary and human importance. Fundamental mechanisms of gene regulation in this group of protistan parasites remain largely uncharacterized. Owing to their medical and veterinary importance, genome sequences are available for several apicomplexan parasites. Their genome sequences reveal an apparent paucity of known transcription factors and the absence of canonical cis-regulatory elements. We have approached the question of gene regulation from a sequence perspective by mining the genomic sequence data to identify putative cis-regulatory elements using a de novo approach. RESULTS: We have identified putative cis-regulatory elements present upstream of functionally related groups of genes and subsequently characterized the function of some of these conserved elements using reporter assays in the parasite. We show a sequence-specific role in gene-expression for 7 out of 8 identified elements. CONCLUSIONS: This work demonstrates the power of pure sequence analysis in the absence of expression data or a priori knowledge of regulatory elements in eukaryotic organisms with compact genomes.
PMID: 19351398 [PubMed - as supplied by publisher]
Identification and functional characterization of cis-regulatory elements in the apicomplexan parasite Toxoplasma gondii
Mullapudi N, Joseph S, Kissinger JC.
ABSTRACT: BACKGROUND: Toxoplasma gondii is a member of the phylum Apicomplexa; a phylum that consists entirely of parasitic organisms that cause several diseases of veterinary and human importance. Fundamental mechanisms of gene regulation in this group of protistan parasites remain largely uncharacterized. Owing to their medical and veterinary importance, genome sequences are available for several apicomplexan parasites. Their genome sequences reveal an apparent paucity of known transcription factors and the absence of canonical cis-regulatory elements. We have approached the question of gene regulation from a sequence perspective by mining the genomic sequence data to identify putative cis-regulatory elements using a de novo approach. RESULTS: We have identified putative cis-regulatory elements present upstream of functionally related groups of genes and subsequently characterized the function of some of these conserved elements using reporter assays in the parasite. We show a sequence-specific role in gene-expression for 7 out of 8 identified elements. CONCLUSIONS: This work demonstrates the power of pure sequence analysis in the absence of expression data or a priori knowledge of regulatory elements in eukaryotic organisms with compact genomes.
PMID: 19351398 [PubMed - as supplied by publisher]
Thursday, April 09, 2009
Drug inhibition of HDAC3 and epigenetic control of differentiation in Apicomplexa parasites
J Exp Med. 2009 Apr 6. [Epub ahead of print]
Drug inhibition of HDAC3 and epigenetic control of differentiation in Apicomplexa parasites
Bougdour A, Maubon D, Baldacci P, Ortet P, Bastien O, Bouillon A, Barale JC, Pelloux H, Ménard R, Hakimi MA.
UMR5163, Laboratoire Adaptation et Pathogénie des Micro-organismes, Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier Grenoble 1, BP 170, 38042 Grenoble, Cedex 09, France.
Plasmodium and Toxoplasma are parasites of major medical importance that belong to the Apicomplexa phylum of protozoa. These parasites transform into various stages during their life cycle and express a specific set of proteins at each stage. Although little is yet known of how gene expression is controlled in Apicomplexa, histone modifications, particularly acetylation, are emerging as key regulators of parasite differentiation and stage conversion. We investigated the anti-Apicomplexa effect of FR235222, a histone deacetylase inhibitor (HDACi). We show that FR235222 is active against a variety of Apicomplexa genera, including Plasmodium and Toxoplasma, and is more potent than other HDACi's such as trichostatin A and the clinically relevant compound pyrimethamine. We identify T. gondii HDAC3 (TgHDAC3) as the target of FR235222 in Toxoplasma tachyzoites and demonstrate the crucial role of the conserved and Apicomplexa HDAC-specific residue TgHDAC3 T99 in the inhibitory activity of the drug. We also show that FR235222 induces differentiation of the tachyzoite (replicative) into the bradyzoite (nonreplicative) stage. Additionally, via its anti-TgHDAC3 activity, FR235222 influences the expression of approximately 370 genes, a third of which are stage-specifically expressed. These results identify FR235222 as a potent HDACi of Apicomplexa, and establish HDAC3 as a central regulator of gene expression and stage conversion in Toxoplasma and, likely, other Apicomplexa.
PMID: 19349466 [PubMed - as supplied by publisher]
Drug inhibition of HDAC3 and epigenetic control of differentiation in Apicomplexa parasites
Bougdour A, Maubon D, Baldacci P, Ortet P, Bastien O, Bouillon A, Barale JC, Pelloux H, Ménard R, Hakimi MA.
UMR5163, Laboratoire Adaptation et Pathogénie des Micro-organismes, Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier Grenoble 1, BP 170, 38042 Grenoble, Cedex 09, France.
Plasmodium and Toxoplasma are parasites of major medical importance that belong to the Apicomplexa phylum of protozoa. These parasites transform into various stages during their life cycle and express a specific set of proteins at each stage. Although little is yet known of how gene expression is controlled in Apicomplexa, histone modifications, particularly acetylation, are emerging as key regulators of parasite differentiation and stage conversion. We investigated the anti-Apicomplexa effect of FR235222, a histone deacetylase inhibitor (HDACi). We show that FR235222 is active against a variety of Apicomplexa genera, including Plasmodium and Toxoplasma, and is more potent than other HDACi's such as trichostatin A and the clinically relevant compound pyrimethamine. We identify T. gondii HDAC3 (TgHDAC3) as the target of FR235222 in Toxoplasma tachyzoites and demonstrate the crucial role of the conserved and Apicomplexa HDAC-specific residue TgHDAC3 T99 in the inhibitory activity of the drug. We also show that FR235222 induces differentiation of the tachyzoite (replicative) into the bradyzoite (nonreplicative) stage. Additionally, via its anti-TgHDAC3 activity, FR235222 influences the expression of approximately 370 genes, a third of which are stage-specifically expressed. These results identify FR235222 as a potent HDACi of Apicomplexa, and establish HDAC3 as a central regulator of gene expression and stage conversion in Toxoplasma and, likely, other Apicomplexa.
PMID: 19349466 [PubMed - as supplied by publisher]
The Ins and Outs of Nuclear Trafficking: Unusual Aspects in Apicomplexans Parasites
DNA Cell Biol. 2009 Apr 6. [Epub ahead of print]
The Ins and Outs of Nuclear Trafficking: Unusual Aspects in Apicomplexans Parasites
Frankel MB, Knoll LJ.
Department of Medical Microbiology and Immunology, University of Wisconsin-Madison , Madison, Wisconsin.
Apicomplexa is a phylum within the kingdom Protista that contains some of the most significant threats to public health. One of the members of this phylum, Toxoplasma gondii, is amenable to molecular genetic analyses allowing for the identification of factors critical for colonization and disease. A pathway found to be important for T. gondii pathogenesis is the Ran network of nuclear trafficking. Bioinformatics analysis of apicomplexan genomes shows that while Ran is well conserved, the key regulators of Ran-Regulator of Chromosome Condensation 1 and Ran GTPase activating protein-are either highly divergent or absent. Likewise, several import and export receptor molecules that are crucial for nuclear transport are either not present or have experienced genetic drift such that they are no longer recognizable by bioinformatics tools. In this minireview we describe the basics of nuclear trafficking and compare components within apicomplexans to defined systems in humans and yeast. A detailed analysis of the nuclear trafficking network in these eukaryotes is required to understand how this potentially unique cellular biological pathway contributes to host-parasite interactions.
PMID: 19348590 [PubMed - as supplied by publisher]
The Ins and Outs of Nuclear Trafficking: Unusual Aspects in Apicomplexans Parasites
Frankel MB, Knoll LJ.
Department of Medical Microbiology and Immunology, University of Wisconsin-Madison , Madison, Wisconsin.
Apicomplexa is a phylum within the kingdom Protista that contains some of the most significant threats to public health. One of the members of this phylum, Toxoplasma gondii, is amenable to molecular genetic analyses allowing for the identification of factors critical for colonization and disease. A pathway found to be important for T. gondii pathogenesis is the Ran network of nuclear trafficking. Bioinformatics analysis of apicomplexan genomes shows that while Ran is well conserved, the key regulators of Ran-Regulator of Chromosome Condensation 1 and Ran GTPase activating protein-are either highly divergent or absent. Likewise, several import and export receptor molecules that are crucial for nuclear transport are either not present or have experienced genetic drift such that they are no longer recognizable by bioinformatics tools. In this minireview we describe the basics of nuclear trafficking and compare components within apicomplexans to defined systems in humans and yeast. A detailed analysis of the nuclear trafficking network in these eukaryotes is required to understand how this potentially unique cellular biological pathway contributes to host-parasite interactions.
PMID: 19348590 [PubMed - as supplied by publisher]
Sunday, April 05, 2009
Apicomplexan Parasites Co-Opt Host Calpains to Facilitate Their Escape from Infected Cells
Science. 2009 Apr 2. [Epub ahead of print]
Apicomplexan Parasites Co-Opt Host Calpains to Facilitate Their Escape from Infected Cells
Chandramohanadas R, Davis PH, Beiting DP, Harbut MB, Darling C, Velmourougane G, Lee MY, Greer PA, Roos DS, Greenbaum DC.
Department of Pharmacology, University of Pennsylvania, Philadelphia, PA 19104, USA.
Apicomplexan parasites, including Plasmodium falciparum and Toxoplasma gondii (the causative agents of malaria and toxoplasmosis, respectively) are responsible for significant morbidity and mortality worldwide. These pathogenic protozoa replicate within an intracellular vacuole inside infected host cells, from which they must escape to initiate a new lytic cycle. Integrating cell biological, pharmacological and genetic approaches, we provide evidence that both Plasmodium and Toxoplasma hijack host cell calpain proteases to facilitate parasite egress. Immunodepletion or inhibition of calpain-1 in hypotonically lysed and resealed erythrocytes prevented the escape of P. falciparum parasites, which was restored by adding purified calpain-1. Similarly, efficient egress of T. gondii from mammalian fibroblasts was blocked by either siRNA-mediated suppression or genetic deletion of calpain activity, and could be restored by genetic complementation.
PMID: 19342550 [PubMed - as supplied by publisher]
Apicomplexan Parasites Co-Opt Host Calpains to Facilitate Their Escape from Infected Cells
Chandramohanadas R, Davis PH, Beiting DP, Harbut MB, Darling C, Velmourougane G, Lee MY, Greer PA, Roos DS, Greenbaum DC.
Department of Pharmacology, University of Pennsylvania, Philadelphia, PA 19104, USA.
Apicomplexan parasites, including Plasmodium falciparum and Toxoplasma gondii (the causative agents of malaria and toxoplasmosis, respectively) are responsible for significant morbidity and mortality worldwide. These pathogenic protozoa replicate within an intracellular vacuole inside infected host cells, from which they must escape to initiate a new lytic cycle. Integrating cell biological, pharmacological and genetic approaches, we provide evidence that both Plasmodium and Toxoplasma hijack host cell calpain proteases to facilitate parasite egress. Immunodepletion or inhibition of calpain-1 in hypotonically lysed and resealed erythrocytes prevented the escape of P. falciparum parasites, which was restored by adding purified calpain-1. Similarly, efficient egress of T. gondii from mammalian fibroblasts was blocked by either siRNA-mediated suppression or genetic deletion of calpain activity, and could be restored by genetic complementation.
PMID: 19342550 [PubMed - as supplied by publisher]
Thursday, April 02, 2009
Severe acquired toxoplasmosis caused by wild cycle of Toxoplasma gondii, French Guiana
Emerg Infect Dis. 2009 Apr;15(4):656-8
Severe acquired toxoplasmosis caused by wild cycle of Toxoplasma gondii, French Guiana
Carme B, Demar M, Ajzenberg D, Dardé ML.
Université des Antilles et de la Guyane, Cayenne, French Guiana.
From 1998 through 2006, 44 cases of severe primary toxoplasmosis were observed in French Guiana in immunocompetent adults. Toxoplasma gondii isolates exhibited an atypical multilocus genotype. Severe disease in humans may result from poor host adaptation to neotropical zoonotic strains of T. gondii circulating in a forest-based cycle.
PMID: 19331765 [PubMed - in process]
Severe acquired toxoplasmosis caused by wild cycle of Toxoplasma gondii, French Guiana
Carme B, Demar M, Ajzenberg D, Dardé ML.
Université des Antilles et de la Guyane, Cayenne, French Guiana.
From 1998 through 2006, 44 cases of severe primary toxoplasmosis were observed in French Guiana in immunocompetent adults. Toxoplasma gondii isolates exhibited an atypical multilocus genotype. Severe disease in humans may result from poor host adaptation to neotropical zoonotic strains of T. gondii circulating in a forest-based cycle.
PMID: 19331765 [PubMed - in process]
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