Eukaryot Cell. 2009 Sep 25. [Epub ahead of print]
Suggestive evidence for Darwinian selection against asparagine-linked glycans of Plasmodium and Toxoplasma
Bushkin GG, Ratner DM, Cui J, Banerjee S, Duraisingh MT, Jennings CV, Dvorin JD, Gubbels MJ, Robertson SD, Steffen M, O'Keefe BR, Robbins PW, Samuelson J.
Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts 02118; Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts 02115; Department of Biology, Boston College, Chestnut Hill, Massachusetts 02467; Department of Pathology and Laboratory Medicine, Boston University Medical School, Boston, Massachusetts 02118; Molecular Targets Development Program, Center for Cancer Research, NCI-Frederick, Frederick, Maryland 21702.
We are interested in asparagine-linked glycans (N-glycans) of Plasmodium and Toxoplasma, because their N-glycan structures have been controversial and because we hypothesize that there might be selection against N-glycans in nucleus-encoded proteins that must pass through the ER prior to threading into the apicoplast. In support of our hypothesis, we observed the following. First, in protists with apicoplasts, there is extensive secondary loss of Alg enzymes that make lipid-linked precursors to N-glycans. Theileria makes no N-glycans, and Plasmodium makes a severely truncated N-glycan precursor composed of one or two GlcNAc residues. Second, secreted proteins of Toxoplasma, which uses its own 10-sugar precursor (Glc3Man5GlcNAc2) and the host 14-sugar precursor (Glc3Man9GlcNAc2) to make N-glycans, have very few sites for N-glycosylation, and there is additional selection against N-glycan sites in its apicoplast-targeted proteins. Third, while the GlcNAc-binding Griffonia simplicifolia lectin II labels ER, rhoptries, and surface of Plasmodia, there is no apicoplast labeling. Similarly, the anti-retroviral lectin cyanovirin-N, which binds to N-glycans of Toxoplasma, labels ER and rhoptries, but there is no apicoplast labeling. We conclude that possible selection against N-glycans in protists with apicoplasts occurs by eliminating N-glycans (Theileria), reducing their length (Plasmodium), or by reducing the number of N-glycan sites (Toxoplasma). In addition, occupation of N-glycan sites is markedly reduced in apicoplast proteins versus some secretory proteins in both Plasmodium and Toxoplasma.
PMID: 19783771 [PubMed - as supplied by publisher]
Wednesday, September 30, 2009
Thursday, September 24, 2009
Post Doctoral fellowships available
Post Doctoral fellowships announcement:
The Toxoplasmosis Research Institute and Center at The University of Chicago is seeking three imaginative and highly motivated postdoctoral fellows for NIH and Foundation funded positions who are interested in focusing their research on Toxoplasma gondii as it is important in human infections and diseases.
These positions are for scientists with a PhD, MD, or MD/PhD, outstanding prior accomplishments and publications, and who are interested in working in the following areas: human host and pathogen interactions (particularly T. gondii) especially as this involves the brain and immune system; molecular biology and biochemistry forming a basis for medicine development particularly to eliminate the encysted form of the parasite; and immunology and genetics forming a basis for vaccine development and understanding protection and pathogenesis. Prior work with Toxoplasma or other apicomplexan parasites such as Plasmodia and experience in other relevant areas (including cell biology, bioinformatics, systems biology, neurosciences and neuroimaging) are considered special, additional strengths.
The overall goals of work in our laboratory and programs are to better understand, prevent and cure this human infection. Exceptional opportunities for research are available in the areas of pathogenesis involving genetics, molecular medicine, immunology, molecular parasitology, gene regulation of parasite and host, biochemistry, medicinal chemistry, bioinformatics and systems biology, neuroscience and human diseases. There are ongoing projects in these areas. These projects are in the context of a clinical center providing medical care for those with toxoplasmosis and a study of the effects of Toxoplasma infection across the human lifetime with and without treatment. Representative publications from our research group include: Nature vol. 393, pages 801-805 (1998); PNAS vol. 100, pages 14281-14286 (2003); CID vol. 42, pages 1383-1394 (2006); PLoS Neglected Tropical Diseases vol. 2, e190 (2008); PLoS One vol. 3, e2285 (2008).
Work takes place in a friendly, interactive and collaborative laboratory and clinical center which are set in a vibrant and scholarly intellectual University community. The University has strong educational and research programs in each of the broad areas listed above with outstanding students and is located in a quiet residential community within 10 minutes to central downtown Chicago. More information about the University can be found at (http://www.uchicago.edu/). Chicago is an exciting, complex and beautiful major US city with all types of galleries, museums, theaters, music venues, and restaurants. There are many other activities, beaches, boating, and unique neighborhoods and suburbs. More information about Chicago is available at http://www.explorechicago.org/city/en.html
To apply, please submit the following by e-mail to Dr. Rima McLeod (rmcleod@midway.uchicago.edu): curriculum vitae, 1-2 page summary of research interests, major accomplishments and future goals and 3 letters of reference with contact information.
The Toxoplasmosis Research Institute and Center at The University of Chicago is seeking three imaginative and highly motivated postdoctoral fellows for NIH and Foundation funded positions who are interested in focusing their research on Toxoplasma gondii as it is important in human infections and diseases.
These positions are for scientists with a PhD, MD, or MD/PhD, outstanding prior accomplishments and publications, and who are interested in working in the following areas: human host and pathogen interactions (particularly T. gondii) especially as this involves the brain and immune system; molecular biology and biochemistry forming a basis for medicine development particularly to eliminate the encysted form of the parasite; and immunology and genetics forming a basis for vaccine development and understanding protection and pathogenesis. Prior work with Toxoplasma or other apicomplexan parasites such as Plasmodia and experience in other relevant areas (including cell biology, bioinformatics, systems biology, neurosciences and neuroimaging) are considered special, additional strengths.
The overall goals of work in our laboratory and programs are to better understand, prevent and cure this human infection. Exceptional opportunities for research are available in the areas of pathogenesis involving genetics, molecular medicine, immunology, molecular parasitology, gene regulation of parasite and host, biochemistry, medicinal chemistry, bioinformatics and systems biology, neuroscience and human diseases. There are ongoing projects in these areas. These projects are in the context of a clinical center providing medical care for those with toxoplasmosis and a study of the effects of Toxoplasma infection across the human lifetime with and without treatment. Representative publications from our research group include: Nature vol. 393, pages 801-805 (1998); PNAS vol. 100, pages 14281-14286 (2003); CID vol. 42, pages 1383-1394 (2006); PLoS Neglected Tropical Diseases vol. 2, e190 (2008); PLoS One vol. 3, e2285 (2008).
Work takes place in a friendly, interactive and collaborative laboratory and clinical center which are set in a vibrant and scholarly intellectual University community. The University has strong educational and research programs in each of the broad areas listed above with outstanding students and is located in a quiet residential community within 10 minutes to central downtown Chicago. More information about the University can be found at (http://www.uchicago.edu/). Chicago is an exciting, complex and beautiful major US city with all types of galleries, museums, theaters, music venues, and restaurants. There are many other activities, beaches, boating, and unique neighborhoods and suburbs. More information about Chicago is available at http://www.explorechicago.org/city/en.html
To apply, please submit the following by e-mail to Dr. Rima McLeod (rmcleod@midway.uchicago.edu): curriculum vitae, 1-2 page summary of research interests, major accomplishments and future goals and 3 letters of reference with contact information.
Silencing of tachyzoite enolase 2 alters nuclear targeting of bradyzoite enolase 1
Microbes Infect. 2009 Sep 18. [Epub ahead of print]
Silencing of tachyzoite enolase 2 alters nuclear targeting of bradyzoite enolase 1 in Toxoplasma gondii
Holmes M, Liwak U, Pricop I, Wang X, Tomavo S, Ananvoranich S.
Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada.
In Toxoplasma gondii, an intracellular parasite of the phylum Apicomplexa, two isoforms of enolase (ENO1 and ENO2) are expressed in stage-specific manner. ENO2 is expressed only in rapidly growing tachyzoites, while ENO1 is in slowly growing bradyzoites. Interestingly, the localization of ENO1 and ENO2 in the nuclear compartment has suggested possible roles of the proteins in gene regulation and/or cell cycle. To understand the physiological role of ENO2 in T. gondii, the expression of ENO2 was silenced using a homologous gene silencing procedure. The introduction or expression of ENO2 dsRNA successfully silenced the expression of ENO2 at the levels of transcripts and proteins. While there was no change in the growth rate of both tachyzoites and bradyzoites, a subtle phenotypic change was observed in the localization of the ENO1 gene product in the bradyzoite stage.
PMID: 19770069 [PubMed - as supplied by publisher]
Silencing of tachyzoite enolase 2 alters nuclear targeting of bradyzoite enolase 1 in Toxoplasma gondii
Holmes M, Liwak U, Pricop I, Wang X, Tomavo S, Ananvoranich S.
Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada.
In Toxoplasma gondii, an intracellular parasite of the phylum Apicomplexa, two isoforms of enolase (ENO1 and ENO2) are expressed in stage-specific manner. ENO2 is expressed only in rapidly growing tachyzoites, while ENO1 is in slowly growing bradyzoites. Interestingly, the localization of ENO1 and ENO2 in the nuclear compartment has suggested possible roles of the proteins in gene regulation and/or cell cycle. To understand the physiological role of ENO2 in T. gondii, the expression of ENO2 was silenced using a homologous gene silencing procedure. The introduction or expression of ENO2 dsRNA successfully silenced the expression of ENO2 at the levels of transcripts and proteins. While there was no change in the growth rate of both tachyzoites and bradyzoites, a subtle phenotypic change was observed in the localization of the ENO1 gene product in the bradyzoite stage.
PMID: 19770069 [PubMed - as supplied by publisher]
Wednesday, September 23, 2009
Evidence for high levels of vertical transmission in Toxoplasma
Parasitology. 2009 Sep 21:1-9. [Epub ahead of print]
Evidence for high levels of vertical transmission in Toxoplasma gondii
Hide G, Morley EK, Hughes JM, Gerwash O, Elmahaishi MS, Elmahaishi KH, Thomasson D, Wright EA, Williams RH, Murphy RG, Smith JE.
Centre for Parasitology and Disease Research, School of Environment and Life Sciences, University of Salford, Salford, M5 4WT, UK.
SUMMARYToxoplasma gondii is a highly ubiquitous and prevalent parasite. Despite the cat being the only definitive host, it is found in almost all geographical areas and warm blooded animals. Three routes of transmission are recognised: ingestion of oocysts shed by the cat, carnivory and congenital transmission. In natural populations, it is difficult to establish the relative importance of these routes. This paper reviews recent work in our laboratory which suggests that congenital transmission may be much more important than previously thought. Using PCR detection of the parasite, studies in sheep show that congenital transmission may occur in as many as 66% of pregnancies. Furthermore, in families of sheep on the same farm, exposed to the same sources of oocysts, significant divergent prevalences of Toxoplasma infection and abortion are found between different families. The data suggest that breeding from infected ewes increases the risk of subsequent abortion and infection in lambs. Congenital transmission rates in a natural population of mice were found to be 75%. Interestingly, congenital transmission rates in humans were measured at 19.8%. The results presented in these studies differ from those of other published studies and suggest that vertical transmission may be much more important than previously thought.
PMID: 19765335 [PubMed - as supplied by publisher]
Evidence for high levels of vertical transmission in Toxoplasma gondii
Hide G, Morley EK, Hughes JM, Gerwash O, Elmahaishi MS, Elmahaishi KH, Thomasson D, Wright EA, Williams RH, Murphy RG, Smith JE.
Centre for Parasitology and Disease Research, School of Environment and Life Sciences, University of Salford, Salford, M5 4WT, UK.
SUMMARYToxoplasma gondii is a highly ubiquitous and prevalent parasite. Despite the cat being the only definitive host, it is found in almost all geographical areas and warm blooded animals. Three routes of transmission are recognised: ingestion of oocysts shed by the cat, carnivory and congenital transmission. In natural populations, it is difficult to establish the relative importance of these routes. This paper reviews recent work in our laboratory which suggests that congenital transmission may be much more important than previously thought. Using PCR detection of the parasite, studies in sheep show that congenital transmission may occur in as many as 66% of pregnancies. Furthermore, in families of sheep on the same farm, exposed to the same sources of oocysts, significant divergent prevalences of Toxoplasma infection and abortion are found between different families. The data suggest that breeding from infected ewes increases the risk of subsequent abortion and infection in lambs. Congenital transmission rates in a natural population of mice were found to be 75%. Interestingly, congenital transmission rates in humans were measured at 19.8%. The results presented in these studies differ from those of other published studies and suggest that vertical transmission may be much more important than previously thought.
PMID: 19765335 [PubMed - as supplied by publisher]
Moving towards an integrated approach to molecular detection and identification of Toxoplasma
Parasitology. 2009 Sep 21:1-11. [Epub ahead of print]
Moving towards an integrated approach to molecular detection and identification of Toxoplasma gondii
Su C, Shwab EK, Zhou P, Zhu XQ, Dubey JP.
Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
SUMMARYThe development of simple, sensitive and rapid methods for the detection and identification of Toxoplasma gondii is important for the diagnosis and epidemiological studies of the zoonotic disease toxoplasmosis. In the past 2 decades, molecular methods based on a variety of genetic markers have been developed, each with its advantages and limitations. The application of these methods has generated invaluable information to enhance our understanding of the epidemiology, population genetics and phylogeny of T. gondii. However, since most studies focused solely on the detection but not genetic characterization of T. gondii, the information obtained was limited. In this review, we discuss some widely used molecular methods and propose an integrated approach for the detection and identification of T. gondii, in order to generate maximum information for epidemiological, population and phylogenetic studies of this key pathogen.
PMID: 19765337 [PubMed - as supplied by publisher]
Moving towards an integrated approach to molecular detection and identification of Toxoplasma gondii
Su C, Shwab EK, Zhou P, Zhu XQ, Dubey JP.
Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
SUMMARYThe development of simple, sensitive and rapid methods for the detection and identification of Toxoplasma gondii is important for the diagnosis and epidemiological studies of the zoonotic disease toxoplasmosis. In the past 2 decades, molecular methods based on a variety of genetic markers have been developed, each with its advantages and limitations. The application of these methods has generated invaluable information to enhance our understanding of the epidemiology, population genetics and phylogeny of T. gondii. However, since most studies focused solely on the detection but not genetic characterization of T. gondii, the information obtained was limited. In this review, we discuss some widely used molecular methods and propose an integrated approach for the detection and identification of T. gondii, in order to generate maximum information for epidemiological, population and phylogenetic studies of this key pathogen.
PMID: 19765337 [PubMed - as supplied by publisher]
Monday, September 21, 2009
Position available: Research Associate (Assistant Professor) - Toxoplasmosis Center
Research Associate (Assistant Professor) - Toxoplasmosis Center
The Toxoplasmosis Research Institute and Center at The University of Chicago is seeking a full-time Research Associate (Assistant Professor) to work in areas of human host Toxoplasma gondii interactions, especially as these interactions involve the brain. The primary activity of a Research Associate (Assistant Professor) is academic research in association with a faculty member or team. Qualified applicants must have a PhD, MD, or MD/PhD and outstanding post doctoral accomplishments and publications. Skills in molecular biology and biochemistry, especially as they form a basis for development of medicines effective against tachyzoites and the persistent encysted form of the parasite, required. Additional areas of preferred expertise include: immunology and genetics forming a basis for vaccine development and understanding protection and pathogenesis of T. gondii infection; other apicomplexan parasites (such as Plasmodia); and other relevant areas including cell biology, bioinformatics, systems biology, neurosciences, and neuroimaging. Compensation is dependent upon qualifications and includes a generous package of fringe benefits.
Qualified applicants must apply online at the University of Chicago academic career opportunities site: http://academiccareers.uchicago.edu/applicants/Central?quickFind=50636 by uploading a current CV and a 1-2 page summary of research interests, major accomplishments, and future goals. Submission of full contact information for at least three scholars from whom letters of support will be requested is also preferred.
The University of Chicago is an Affirmative Action / Equal Opportunity Employer.
The Toxoplasmosis Research Institute and Center at The University of Chicago is seeking a full-time Research Associate (Assistant Professor) to work in areas of human host Toxoplasma gondii interactions, especially as these interactions involve the brain. The primary activity of a Research Associate (Assistant Professor) is academic research in association with a faculty member or team. Qualified applicants must have a PhD, MD, or MD/PhD and outstanding post doctoral accomplishments and publications. Skills in molecular biology and biochemistry, especially as they form a basis for development of medicines effective against tachyzoites and the persistent encysted form of the parasite, required. Additional areas of preferred expertise include: immunology and genetics forming a basis for vaccine development and understanding protection and pathogenesis of T. gondii infection; other apicomplexan parasites (such as Plasmodia); and other relevant areas including cell biology, bioinformatics, systems biology, neurosciences, and neuroimaging. Compensation is dependent upon qualifications and includes a generous package of fringe benefits.
Qualified applicants must apply online at the University of Chicago academic career opportunities site: http://academiccareers.uchicago.edu/applicants/Central?quickFind=50636 by uploading a current CV and a 1-2 page summary of research interests, major accomplishments, and future goals. Submission of full contact information for at least three scholars from whom letters of support will be requested is also preferred.
The University of Chicago is an Affirmative Action / Equal Opportunity Employer.
Friday, September 18, 2009
Murine neonatal infection provides an efficient model for congenital ocular toxoplasmosis
Exp Parasitol. 2009 Sep 12. [Epub ahead of print]
Murine neonatal infection provides an efficient model for congenital ocular toxoplasmosis
Lahmar I, Guinard M, Sauer A, Marcellin L, Abdelrahman T, Roux M, Mousli M, Moussa A, Babba H, Pfaff AW, Candolfi E.
Institut de Parasitologie et de Pathologie Tropicale, EA 4438, Université de Strasbourg, France; Laboratoire de Parasitologie Mycologie 99-UR/08-05 Faculté de Pharmacie, Monastir, Tunisia.
Congenital infection is one of the most serious settings of infection with the apicomplexan parasite Toxoplasma gondii. Ocular diseases, such as retinochoroiditis, are the most common sequels of such infection in utero. However, while numerous studies have investigated the physiopathology of acquired toxoplasmosis, congenital infection has been largely neglected so far. Here, we establish a mouse model of congenital ocular toxoplasmosis. Parasite load and ocular pathology have been followed for the first four weeks of life. Ocular infection developed slowly compared to cerebral infection. Even after four weeks, not all eyes were infected and ocular parasite load was low. Therefore, we evaluated a scheme of neonatal infection to overcome problems associated with congenital infection. Development of infection and physiopathology was similar, but at a higher, more reliable rate. In summary, we have established a valuable model of neonatal ocular toxoplasmosis, which facilitates the research of the underlying physiopathological mechanisms and new diagnostic approaches of this pathology.
PMID: 19755119 [PubMed - as supplied by publisher]
Murine neonatal infection provides an efficient model for congenital ocular toxoplasmosis
Lahmar I, Guinard M, Sauer A, Marcellin L, Abdelrahman T, Roux M, Mousli M, Moussa A, Babba H, Pfaff AW, Candolfi E.
Institut de Parasitologie et de Pathologie Tropicale, EA 4438, Université de Strasbourg, France; Laboratoire de Parasitologie Mycologie 99-UR/08-05 Faculté de Pharmacie, Monastir, Tunisia.
Congenital infection is one of the most serious settings of infection with the apicomplexan parasite Toxoplasma gondii. Ocular diseases, such as retinochoroiditis, are the most common sequels of such infection in utero. However, while numerous studies have investigated the physiopathology of acquired toxoplasmosis, congenital infection has been largely neglected so far. Here, we establish a mouse model of congenital ocular toxoplasmosis. Parasite load and ocular pathology have been followed for the first four weeks of life. Ocular infection developed slowly compared to cerebral infection. Even after four weeks, not all eyes were infected and ocular parasite load was low. Therefore, we evaluated a scheme of neonatal infection to overcome problems associated with congenital infection. Development of infection and physiopathology was similar, but at a higher, more reliable rate. In summary, we have established a valuable model of neonatal ocular toxoplasmosis, which facilitates the research of the underlying physiopathological mechanisms and new diagnostic approaches of this pathology.
PMID: 19755119 [PubMed - as supplied by publisher]
Thursday, September 17, 2009
Major role for CD8 T cells in the protection against Toxoplasma gondii following dendritic cell vaccination
Parasite Immunol. 2009 Oct;31(10):631-40.
Major role for CD8 T cells in the protection against Toxoplasma gondii following dendritic cell vaccination
Guiton R, Zagani R, Dimier-Poisson I.
Université François Rabelais Tours, INRA, UMR 0483 Université-INRA d'Immunologie Parasitaire et Vaccinologie, Biothérapies anti-infectieuses, IFR 136 agents transmissibles en Infectiologie, UFR des Sciences Pharmaceutiques, Tours, France.
Toxoplasma gondii is the causative agent of toxoplasmosis, a worldwide zoonosis for which an effective vaccine is needed. Vaccination with pulsed dendritic cells is very efficient but their use in a vaccination protocol is unconceivable. Nevertheless, unravelling the induced effector mechanisms is crucial to design new vaccine strategies. We vaccinated CBA/J mice with parasite extract-pulsed dendritic cells, challenged them with T. gondii cysts and carried out in vivo depletion of CD4(+) or CD8(+) T lymphocytes to study the subsequent cellular immune response and protective mechanisms. CD4(+) lymphocytes were poorly implicated either in spleen and mesenteric lymph node (MLN) cytokine secretion or in mice protection. By contrast, the increasing number of intracerebral cysts and depletion of CD8(+) cells were strongly correlated, revealing a prominent role for CD8(+) lymphocytes in the protection of mice. Splenic CD8(+) lymphocytes induce a strong Th1 response controlled by a Th2 response whereas CD8(+) cells from MLNs inhibit both Th1 and Th2 responses. CD8(+) cells are the main effectors following dendritic cell vaccination and Toxoplasma infection while CD4(+) T cells only play a minor role. This contrasts with T. gondii infection which elicits the generation of CD4(+) and CD8(+) T cells that provide protective immunity.
PMID: 19751475 [PubMed - in process]
Major role for CD8 T cells in the protection against Toxoplasma gondii following dendritic cell vaccination
Guiton R, Zagani R, Dimier-Poisson I.
Université François Rabelais Tours, INRA, UMR 0483 Université-INRA d'Immunologie Parasitaire et Vaccinologie, Biothérapies anti-infectieuses, IFR 136 agents transmissibles en Infectiologie, UFR des Sciences Pharmaceutiques, Tours, France.
Toxoplasma gondii is the causative agent of toxoplasmosis, a worldwide zoonosis for which an effective vaccine is needed. Vaccination with pulsed dendritic cells is very efficient but their use in a vaccination protocol is unconceivable. Nevertheless, unravelling the induced effector mechanisms is crucial to design new vaccine strategies. We vaccinated CBA/J mice with parasite extract-pulsed dendritic cells, challenged them with T. gondii cysts and carried out in vivo depletion of CD4(+) or CD8(+) T lymphocytes to study the subsequent cellular immune response and protective mechanisms. CD4(+) lymphocytes were poorly implicated either in spleen and mesenteric lymph node (MLN) cytokine secretion or in mice protection. By contrast, the increasing number of intracerebral cysts and depletion of CD8(+) cells were strongly correlated, revealing a prominent role for CD8(+) lymphocytes in the protection of mice. Splenic CD8(+) lymphocytes induce a strong Th1 response controlled by a Th2 response whereas CD8(+) cells from MLNs inhibit both Th1 and Th2 responses. CD8(+) cells are the main effectors following dendritic cell vaccination and Toxoplasma infection while CD4(+) T cells only play a minor role. This contrasts with T. gondii infection which elicits the generation of CD4(+) and CD8(+) T cells that provide protective immunity.
PMID: 19751475 [PubMed - in process]
Tuesday, September 15, 2009
Apoptosis in Toxoplasma gondii activated T cells
Microb Pathog. 2009 Sep 10. [Epub ahead of print]
Apoptosis in Toxoplasma gondii activated T cells: The role of IFNgamma in enhanced alteration of Bcl-2 expression and mitochondrial membrane potential
Begum-Haque S, Haque A, Kasper LH.
Department of Medicine and Microbiology, Dartmouth Medical School Hanover, NH 03755.
In the present study we addressed the question whether Toxoplasma gondii could promote apoptosis in T lymphocytes in the acute stage of infection. Using in vivo activated T cells and then culturing them for a short time, we observed activation induced cell death in T. gondii infected mice. A higher level of activation induced cell death (AICD) was seen in susceptible C57BL/6 mice than in resistant CBA/J mice following infection with the same P strain of parasite. Apoptosis in T cells of susceptible mice was associated with altered induction of Bcl-2/Bax, loss of Mitochondrial Transmembrane Potential. Both CD4+ and CD8+T cells were found to be susceptible to apoptosis; CD4+T cells were sensitive to Fas mediated death whereas CD8+T cells were insensitive to this signal. Caspase inhibitors had less effect on DNA fragmentation in CD4+ compared to CD8+T cells. Exposure of CD4+T cells to anti-IFNgamma mAb resulted in an increase in the number of T cells that were positive for anti-apoptotic molecule Bcl-2 and DiOC6, a cationic dye that accumulates in intact mitochondria. These changes were less noticeable in CD8+T cells following treatment with anti-IFNgamma mAb. These findings provide further insight into the mechanisms of T cell apoptosis in T. gondii infection.
PMID: 19748565 [PubMed - as supplied by publisher]
Apoptosis in Toxoplasma gondii activated T cells: The role of IFNgamma in enhanced alteration of Bcl-2 expression and mitochondrial membrane potential
Begum-Haque S, Haque A, Kasper LH.
Department of Medicine and Microbiology, Dartmouth Medical School Hanover, NH 03755.
In the present study we addressed the question whether Toxoplasma gondii could promote apoptosis in T lymphocytes in the acute stage of infection. Using in vivo activated T cells and then culturing them for a short time, we observed activation induced cell death in T. gondii infected mice. A higher level of activation induced cell death (AICD) was seen in susceptible C57BL/6 mice than in resistant CBA/J mice following infection with the same P strain of parasite. Apoptosis in T cells of susceptible mice was associated with altered induction of Bcl-2/Bax, loss of Mitochondrial Transmembrane Potential. Both CD4+ and CD8+T cells were found to be susceptible to apoptosis; CD4+T cells were sensitive to Fas mediated death whereas CD8+T cells were insensitive to this signal. Caspase inhibitors had less effect on DNA fragmentation in CD4+ compared to CD8+T cells. Exposure of CD4+T cells to anti-IFNgamma mAb resulted in an increase in the number of T cells that were positive for anti-apoptotic molecule Bcl-2 and DiOC6, a cationic dye that accumulates in intact mitochondria. These changes were less noticeable in CD8+T cells following treatment with anti-IFNgamma mAb. These findings provide further insight into the mechanisms of T cell apoptosis in T. gondii infection.
PMID: 19748565 [PubMed - as supplied by publisher]
Potent Fluoro-oligosaccharide Probes of Adhesion in Toxoplasmosis
Chembiochem. 2009 Sep 11. [Epub ahead of print]
Potent Fluoro-oligosaccharide Probes of Adhesion in Toxoplasmosis
Allman SA, Jensen HH, Vijayakrishnan B, Garnett JA, Leon E, Liu Y, Anthony DC, Sibson NR, Feizi T, Matthews S, Davis BG.
Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA (UK), Fax: (+44) 1865-285-002.
Unnatural, NMR- and MRI-active fluorinated sugar probes, designed and synthesised to bind to the pathogenic protein TgMIC1 from Toxoplasma gondii, were found to display binding potency equal to and above that of the natural ligand. Dissection of the binding mechanism and modes, including the first X-ray crystal structures of a fluoro-oligosaccharide bound to a lectin, demonstrate that it is possible to create effective fluorinated probe ligands for the study of, and perhaps intervention in, sugar-protein binding events.
PMID: 19750531 [PubMed - as supplied by publisher]
Potent Fluoro-oligosaccharide Probes of Adhesion in Toxoplasmosis
Allman SA, Jensen HH, Vijayakrishnan B, Garnett JA, Leon E, Liu Y, Anthony DC, Sibson NR, Feizi T, Matthews S, Davis BG.
Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA (UK), Fax: (+44) 1865-285-002.
Unnatural, NMR- and MRI-active fluorinated sugar probes, designed and synthesised to bind to the pathogenic protein TgMIC1 from Toxoplasma gondii, were found to display binding potency equal to and above that of the natural ligand. Dissection of the binding mechanism and modes, including the first X-ray crystal structures of a fluoro-oligosaccharide bound to a lectin, demonstrate that it is possible to create effective fluorinated probe ligands for the study of, and perhaps intervention in, sugar-protein binding events.
PMID: 19750531 [PubMed - as supplied by publisher]
Sunday, September 13, 2009
Zoonoses Public Health. - Toxoplasma feature
Dabritz HA, Conrad PA.
Cats and Toxoplasma: Implications for Public Health.
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744306 [PubMed - as supplied by publisher]
Dubey JP.
Toxoplasma gondii Infections in Chickens (Gallus domesticus): Prevalence, Clinical Disease, Diagnosis and Public Health Significance.
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744305 [PubMed - as supplied by publisher]
Hill DE, Haley C, Wagner B, Gamble HR, Dubey JP.
Seroprevalence of and Risk Factors for Toxoplasma gondii in the US Swine Herd Using Sera Collected During the National Animal Health Monitoring Survey (Swine 2006).
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744304 [PubMed - as supplied by publisher]
Innes EA.
A Brief History and Overview of Toxoplasma gondii.
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744303 [PubMed - as supplied by publisher]
Jones JL, Krueger A, Schulkin J, Schantz PM.
Toxoplasmosis Prevention and Testing in Pregnancy, Survey of Obstetrician-Gynaecologists.
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744302 [PubMed - as supplied by publisher]
Petersen E, Vesco G, Villari S, Buffolano W.
What Do We Know About Risk Factors for Infection in Humans with Toxoplasma gondii and How Can We Prevent Infections?
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744301 [PubMed - as supplied by publisher]
Edelhofer R, Prossinger H.
Infection with Toxoplasma gondii during Pregnancy: Seroepidemiological Studies in Austria.
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744300 [PubMed - as supplied by publisher]
Wainwright KE, Lagunas-Solar M, Miller MA, Barr BC, Melli AC, Packham AE, Zeng N, Truong T, Conrad PA.
Radiofrequency-Induced Thermal Inactivation of Toxoplasma gondii Oocysts in Water.
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744299 [PubMed - as supplied by publisher]
Gardner IA, Greiner M, Dubey JP.
Statistical Evaluation of Test Accuracy Studies for Toxoplasma gondii in Food Animal Intermediate Hosts.
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744298 [PubMed - as supplied by publisher]
Cats and Toxoplasma: Implications for Public Health.
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744306 [PubMed - as supplied by publisher]
Dubey JP.
Toxoplasma gondii Infections in Chickens (Gallus domesticus): Prevalence, Clinical Disease, Diagnosis and Public Health Significance.
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744305 [PubMed - as supplied by publisher]
Hill DE, Haley C, Wagner B, Gamble HR, Dubey JP.
Seroprevalence of and Risk Factors for Toxoplasma gondii in the US Swine Herd Using Sera Collected During the National Animal Health Monitoring Survey (Swine 2006).
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744304 [PubMed - as supplied by publisher]
Innes EA.
A Brief History and Overview of Toxoplasma gondii.
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744303 [PubMed - as supplied by publisher]
Jones JL, Krueger A, Schulkin J, Schantz PM.
Toxoplasmosis Prevention and Testing in Pregnancy, Survey of Obstetrician-Gynaecologists.
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744302 [PubMed - as supplied by publisher]
Petersen E, Vesco G, Villari S, Buffolano W.
What Do We Know About Risk Factors for Infection in Humans with Toxoplasma gondii and How Can We Prevent Infections?
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744301 [PubMed - as supplied by publisher]
Edelhofer R, Prossinger H.
Infection with Toxoplasma gondii during Pregnancy: Seroepidemiological Studies in Austria.
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744300 [PubMed - as supplied by publisher]
Wainwright KE, Lagunas-Solar M, Miller MA, Barr BC, Melli AC, Packham AE, Zeng N, Truong T, Conrad PA.
Radiofrequency-Induced Thermal Inactivation of Toxoplasma gondii Oocysts in Water.
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744299 [PubMed - as supplied by publisher]
Gardner IA, Greiner M, Dubey JP.
Statistical Evaluation of Test Accuracy Studies for Toxoplasma gondii in Food Animal Intermediate Hosts.
Zoonoses Public Health. 2009 Sep 10;. [Epub ahead of print]
PMID: 19744298 [PubMed - as supplied by publisher]
The role of specific Toxoplasma gondii molecules in manipulation of innate immunity
Trends Parasitol. 2009 Sep 8. [Epub ahead of print]
The role of specific Toxoplasma gondii molecules in manipulation of innate immunity
Pollard AM, Knoll LJ, Mordue DG.
Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, 1550 Linden Drive, Madison, WI 53706, USA.
Infection with the parasite Toxoplasma gondii stimulates an innate immune response in the host. T. gondii also induces alterations in infected monocytes and dendritic cells that probably contribute to its ability to disseminate and ultimately to establish persistent infection. Recent progress has linked specific parasite molecules to immune stimulation or the ability of the parasite to subvert intracellular signaling pathways in infected cells to evade immunity.
PMID: 19744886 [PubMed - as supplied by publisher]
The role of specific Toxoplasma gondii molecules in manipulation of innate immunity
Pollard AM, Knoll LJ, Mordue DG.
Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, 1550 Linden Drive, Madison, WI 53706, USA.
Infection with the parasite Toxoplasma gondii stimulates an innate immune response in the host. T. gondii also induces alterations in infected monocytes and dendritic cells that probably contribute to its ability to disseminate and ultimately to establish persistent infection. Recent progress has linked specific parasite molecules to immune stimulation or the ability of the parasite to subvert intracellular signaling pathways in infected cells to evade immunity.
PMID: 19744886 [PubMed - as supplied by publisher]
Friday, September 11, 2009
Toxoplasma infection confers resistance against BimS-induced apoptosis by preventing the activation and mitochondrial targeting of Bax
J Cell Sci. 2009 Sep 8. [Epub ahead of print]
Toxoplasma gondii infection confers resistance against BimS-induced apoptosis by preventing the activation and mitochondrial targeting of pro-apoptotic Bax
Hippe D, Weber A, Zhou L, Chang DC, Häcker G, Lüder CG.
In order to accomplish their life style, intracellular pathogens, including the apicomplexan Toxoplasma gondii, subvert the innate apoptotic response of infected host cells. However, the precise mechanisms of parasite interference with the mitochondrial apoptotic pathway remain unknown. Here, we used the conditional expression of the BH3-only protein BimS to pinpoint the interaction of T. gondii with the intrinsic pathway of apoptosis. Infection of epithelial cells with T. gondii dose-dependently abrogated BimS-triggered release of cytochrome c from host-cell mitochondria into the cytosol, induction of activity of caspases 3, 7 and 9, and chromatin condensation. Furthermore, inhibition of apoptosis in parasite-infected lymphocytes counteracted death of Toxoplasma-infected host cells. Although total cellular levels and mitochondrial targeting of BimS was not altered by the infection, the activation of pro-apoptotic effector proteins Bax and Bak was strongly impaired. Inhibition of Bax and Bak activation by T. gondii was seen with regard to their conformational changes, the cytosol-to-mitochondria targeting and the oligomerization of Bax but not their cellular protein levels. Blockade of Bax and Bak activation was not mediated by the upregulation of anti-apoptotic Bcl-2-like proteins following infection. Further, the BH3-mimetic ABT-737 failed to overcome the Toxoplasma-imposed inhibition of BimS-triggered apoptosis. These results indicate that T. gondii targets activation of pro-apoptotic Bax and Bak to inhibit the apoptogenic function of mitochondria and to increase host-cell viability.
PMID: 19737817 [PubMed - as supplied by publisher]
Toxoplasma gondii infection confers resistance against BimS-induced apoptosis by preventing the activation and mitochondrial targeting of pro-apoptotic Bax
Hippe D, Weber A, Zhou L, Chang DC, Häcker G, Lüder CG.
In order to accomplish their life style, intracellular pathogens, including the apicomplexan Toxoplasma gondii, subvert the innate apoptotic response of infected host cells. However, the precise mechanisms of parasite interference with the mitochondrial apoptotic pathway remain unknown. Here, we used the conditional expression of the BH3-only protein BimS to pinpoint the interaction of T. gondii with the intrinsic pathway of apoptosis. Infection of epithelial cells with T. gondii dose-dependently abrogated BimS-triggered release of cytochrome c from host-cell mitochondria into the cytosol, induction of activity of caspases 3, 7 and 9, and chromatin condensation. Furthermore, inhibition of apoptosis in parasite-infected lymphocytes counteracted death of Toxoplasma-infected host cells. Although total cellular levels and mitochondrial targeting of BimS was not altered by the infection, the activation of pro-apoptotic effector proteins Bax and Bak was strongly impaired. Inhibition of Bax and Bak activation by T. gondii was seen with regard to their conformational changes, the cytosol-to-mitochondria targeting and the oligomerization of Bax but not their cellular protein levels. Blockade of Bax and Bak activation was not mediated by the upregulation of anti-apoptotic Bcl-2-like proteins following infection. Further, the BH3-mimetic ABT-737 failed to overcome the Toxoplasma-imposed inhibition of BimS-triggered apoptosis. These results indicate that T. gondii targets activation of pro-apoptotic Bax and Bak to inhibit the apoptogenic function of mitochondria and to increase host-cell viability.
PMID: 19737817 [PubMed - as supplied by publisher]
Induction of protective immunity by multiantigenic DNA vaccine delivered in attenuated Salmonella typhimurium against Toxoplasma gondii infection
Vet Parasitol. 2009 Aug 21. [Epub ahead of print]
Induction of protective immunity by multiantigenic DNA vaccine delivered in attenuated Salmonella typhimurium against Toxoplasma gondii infection in mice
Qu D, Yu H, Wang S, Cai W, Du A.
Key Laboratory of Animal Epidemic Etiology and Immunological Prevention of Ministry of Agriculture, Zhejiang University, Hangzhou 310029, China; Institute of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, Zhejiang 310029, China.
Toxoplasma gondii, capable of infecting all warm blooded animals, is one of the most successful parasites worldwide. It was reported that the single-gene vaccine with SAG1 or MIC3 could only produce partial protection against T. gondii and multiantigenic vaccines were more effective than single ones. In the present study, a multiantigenic DNA vaccine delivered by attenuated Salmonella typhimurium (ZJ111/pSAG1-MIC3) was constructed, which expresses surface protein SAG1 and micronemal protein MIC3. The safety and stability of ZJ111/pSAG1-MIC3 were evaluated and immune response with ZJ111/pSAG1 and ZJ111/pMIC3 were compared. The results of lymphocyte proliferation assay, antibody and cytokine determination show that mice immunized with ZJ111/pSAG1-MIC3 elicited stronger humoral and Th1-type cellular immune responses than other groups. The mice immunized with ZJ111/pSAG1-MIC3 also exhibited significant higher survival time after challenged with T. gondii RH strain. The current study shows that the oral multiantigenic DNA vaccine, ZJ111/pSAG1-MIC3, produces partial protection against T. gondii challenge.
PMID: 19740610 [PubMed - as supplied by publisher]
Induction of protective immunity by multiantigenic DNA vaccine delivered in attenuated Salmonella typhimurium against Toxoplasma gondii infection in mice
Qu D, Yu H, Wang S, Cai W, Du A.
Key Laboratory of Animal Epidemic Etiology and Immunological Prevention of Ministry of Agriculture, Zhejiang University, Hangzhou 310029, China; Institute of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, Zhejiang 310029, China.
Toxoplasma gondii, capable of infecting all warm blooded animals, is one of the most successful parasites worldwide. It was reported that the single-gene vaccine with SAG1 or MIC3 could only produce partial protection against T. gondii and multiantigenic vaccines were more effective than single ones. In the present study, a multiantigenic DNA vaccine delivered by attenuated Salmonella typhimurium (ZJ111/pSAG1-MIC3) was constructed, which expresses surface protein SAG1 and micronemal protein MIC3. The safety and stability of ZJ111/pSAG1-MIC3 were evaluated and immune response with ZJ111/pSAG1 and ZJ111/pMIC3 were compared. The results of lymphocyte proliferation assay, antibody and cytokine determination show that mice immunized with ZJ111/pSAG1-MIC3 elicited stronger humoral and Th1-type cellular immune responses than other groups. The mice immunized with ZJ111/pSAG1-MIC3 also exhibited significant higher survival time after challenged with T. gondii RH strain. The current study shows that the oral multiantigenic DNA vaccine, ZJ111/pSAG1-MIC3, produces partial protection against T. gondii challenge.
PMID: 19740610 [PubMed - as supplied by publisher]
CCR2-dependent intraepithelial lymphocytes mediate inflammatory gut pathology during Toxoplasma gondii infection
Mucosal Immunol. 2009 Sep 9. [Epub ahead of print]
CCR2-dependent intraepithelial lymphocytes mediate inflammatory gut pathology during Toxoplasma gondii infection
Egan C, Craven M, Leng J, Mack M, Simpson K, Denkers E.
Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.
Mice of the C57BL/6 strain develop acute ileal inflammation after infection with the protozoan parasite Toxoplasma gondii. This pathology resembles many key features of human Crohn's disease, including a Th1 cytokine profile with high levels of interferon gamma (IFN-gamma), interleukin 12 (IL)-12, and tumor necrosis factor alpha (TNF)-alpha, presence of pathogenic CD4(+) T cells, and infiltration of gut flora into inflammed tissue. Using CCR2(-/-) mice, we identify a role for this chemokine receptor in the pathogenesis of inflammatory pathology during T. gondii infection. Lack of chemokine (C-C motif) receptor 2 (CCR2) was associated with low levels of CD103(+) T lymphocytes in the intraepithelial compartment, Peyer's patch, and lamina propria relative to wild-type animals. Adoptive transfer of wild-type, but not IFN-gamma(-/-), intraepithelial T lymphocytes converted CCR2 knockout mice from a resistant to susceptible phenotype with respect to parasite-triggered inflammatory gut pathology. These results for the first time show a role for intraepithelial T lymphocytes in pathogenesis of ileitis triggered by a microbial pathogen.Mucosal Immunology advance online publication 9 September 2009. doi:10.1038/mi.2009.105.
PMID: 19741601 [PubMed - as supplied by publisher]
CCR2-dependent intraepithelial lymphocytes mediate inflammatory gut pathology during Toxoplasma gondii infection
Egan C, Craven M, Leng J, Mack M, Simpson K, Denkers E.
Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.
Mice of the C57BL/6 strain develop acute ileal inflammation after infection with the protozoan parasite Toxoplasma gondii. This pathology resembles many key features of human Crohn's disease, including a Th1 cytokine profile with high levels of interferon gamma (IFN-gamma), interleukin 12 (IL)-12, and tumor necrosis factor alpha (TNF)-alpha, presence of pathogenic CD4(+) T cells, and infiltration of gut flora into inflammed tissue. Using CCR2(-/-) mice, we identify a role for this chemokine receptor in the pathogenesis of inflammatory pathology during T. gondii infection. Lack of chemokine (C-C motif) receptor 2 (CCR2) was associated with low levels of CD103(+) T lymphocytes in the intraepithelial compartment, Peyer's patch, and lamina propria relative to wild-type animals. Adoptive transfer of wild-type, but not IFN-gamma(-/-), intraepithelial T lymphocytes converted CCR2 knockout mice from a resistant to susceptible phenotype with respect to parasite-triggered inflammatory gut pathology. These results for the first time show a role for intraepithelial T lymphocytes in pathogenesis of ileitis triggered by a microbial pathogen.Mucosal Immunology advance online publication 9 September 2009. doi:10.1038/mi.2009.105.
PMID: 19741601 [PubMed - as supplied by publisher]
A case of cerebral toxoplasmosis in a pregnant non-immunocompromised patient
Neurol Neurochir Pol. 2009 July-August;43(4):391-395
A case of cerebral toxoplasmosis in a pregnant non-immunocompromised patient
Alapatt JP, Kutty RK, Jose B, Gopi P.
Department of Neurosurgery, Govt. Medical College, Thissur, Kerala, India-673016, e-mail: alapattjp@yahoo.com.
Cerebral toxoplasmosis, a disease of immunocompromised individuals, is rare in immunocompetent persons. We present a case of cerebral toxoplasmosis in a non-immunocompro-mised pregnant woman. Her imaging studies revealed a mass lesion involving the right basal ganglia, periventricular grey matter, midbrain and pons suggesting a neoplastic pathology along with hydrocephalus. She underwent an endoscopic third ventriculostomy and biopsy of the lesion. Postoperatively her consciousness improved as the hydrocephalus was relieved. After a thorough gynaecological examination she gave birth to a healthy child via normal vaginal delivery. The histopathology examination of biopsy suggested an inflammatory pathology. Serological studies for toxoplasmosis were positive. After 6 weeks of anti-toxoplasma treatment follow-up imaging showed a significant decrease in the size of the lesion.
PMID: 19742399 [PubMed - as supplied by publisher]
A case of cerebral toxoplasmosis in a pregnant non-immunocompromised patient
Alapatt JP, Kutty RK, Jose B, Gopi P.
Department of Neurosurgery, Govt. Medical College, Thissur, Kerala, India-673016, e-mail: alapattjp@yahoo.com.
Cerebral toxoplasmosis, a disease of immunocompromised individuals, is rare in immunocompetent persons. We present a case of cerebral toxoplasmosis in a non-immunocompro-mised pregnant woman. Her imaging studies revealed a mass lesion involving the right basal ganglia, periventricular grey matter, midbrain and pons suggesting a neoplastic pathology along with hydrocephalus. She underwent an endoscopic third ventriculostomy and biopsy of the lesion. Postoperatively her consciousness improved as the hydrocephalus was relieved. After a thorough gynaecological examination she gave birth to a healthy child via normal vaginal delivery. The histopathology examination of biopsy suggested an inflammatory pathology. Serological studies for toxoplasmosis were positive. After 6 weeks of anti-toxoplasma treatment follow-up imaging showed a significant decrease in the size of the lesion.
PMID: 19742399 [PubMed - as supplied by publisher]
Thursday, September 10, 2009
Host cholesterol and inflammation as common key regulators of toxoplasmosis and artherosclerosis development
Expert Rev Anti Infect Ther. 2009 Sep;7(7):807-19.
Host cholesterol and inflammation as common key regulators of toxoplasmosis and artherosclerosis development
Portugal LR, Fernandes LR, Alvarez-Leite JI.
Biological Sciences, Future Faculty -36900-000, Manhuaçu, MG, Brazil.
Atherosclerosis and toxoplasmosis are two widely prevalent diseases worldwide. The relationship between these diseases is now being elucidated. Atherosclerosis is a disease with three main components: increased blood lipoprotein/cholesterol and their deposition in the arterial wall, an important Th1-mediated proinflammatory reaction and thrombogenic status. Toxoplasma gondii, in turn, is dependent on host cholesterol for optimal intracellular growth and replication. As a result, host cholesterol will be cleared from the blood, reducing plasma low-density lipoprotein, a crucial atherosclerosis risk factor. On the other hand, T. gondii infection elicits an important Th1 systemic inflammatory response in the host. Therefore, this additional proinflammatory stimulus may impose an enhanced pro-atherogenic environment in the host. As result, the association between these two diseases in one individual could change the course of atherosclerosis. In this review, we demonstrate that the host-parasite relationship is complex and that the outcome of each disease is dependent on the availability of intracellular cholesterol, as well as the intensity of the inflammatory reaction triggered by the parasite. We also discuss the possible clinical implications of these studies.
PMID: 19735223 [PubMed - in process]
Host cholesterol and inflammation as common key regulators of toxoplasmosis and artherosclerosis development
Portugal LR, Fernandes LR, Alvarez-Leite JI.
Biological Sciences, Future Faculty -36900-000, Manhuaçu, MG, Brazil.
Atherosclerosis and toxoplasmosis are two widely prevalent diseases worldwide. The relationship between these diseases is now being elucidated. Atherosclerosis is a disease with three main components: increased blood lipoprotein/cholesterol and their deposition in the arterial wall, an important Th1-mediated proinflammatory reaction and thrombogenic status. Toxoplasma gondii, in turn, is dependent on host cholesterol for optimal intracellular growth and replication. As a result, host cholesterol will be cleared from the blood, reducing plasma low-density lipoprotein, a crucial atherosclerosis risk factor. On the other hand, T. gondii infection elicits an important Th1 systemic inflammatory response in the host. Therefore, this additional proinflammatory stimulus may impose an enhanced pro-atherogenic environment in the host. As result, the association between these two diseases in one individual could change the course of atherosclerosis. In this review, we demonstrate that the host-parasite relationship is complex and that the outcome of each disease is dependent on the availability of intracellular cholesterol, as well as the intensity of the inflammatory reaction triggered by the parasite. We also discuss the possible clinical implications of these studies.
PMID: 19735223 [PubMed - in process]
Tuesday, September 08, 2009
A highly sensitive FRET-based approach reveals secretion of the actin-binding protein toxofilin during Toxoplasma gondii infection
Cell Microbiol. 2009 Sep 2. [Epub ahead of print]
A highly sensitive FRET-based approach reveals secretion of the actin-binding protein toxofilin during Toxoplasma gondii infection
Lodoen MB, Gerke C, Boothroyd JC.
Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305.
Abstract We have utilized a highly sensitive approach based on fluorescence resonance energy transfer (FRET) and beta-lactamase (BLA) (Zlokarnik et al., 1998), which we adapted for the detection of Toxoplasma gondii secreted proteins. This assay revealed that the actin-binding protein toxofilin appears to be secreted into host cells during invasion. To determine the function of toxofilin during infection, we engineered a type I (RH strain) parasite with a targeted deletion of the toxofilin gene and compared the phenotypes of control and toxofilin knock-out (Deltatxf) parasites in several in vitro assays, including invasion, growth, and gliding motility, and egress of the Deltatxf parasites, as well as F-actin staining, phagocytosis and migration of cells infected with Deltatxf parasites or wild-type controls. Despite its apparent secretion into host cells and its ability to bind to and modulate host actin, we observed that toxofilin does not appear to play a role in these processes, under the conditions we examined, and we report these findings here.
PMID: 19732057 [PubMed - as supplied by publisher]
A highly sensitive FRET-based approach reveals secretion of the actin-binding protein toxofilin during Toxoplasma gondii infection
Lodoen MB, Gerke C, Boothroyd JC.
Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305.
Abstract We have utilized a highly sensitive approach based on fluorescence resonance energy transfer (FRET) and beta-lactamase (BLA) (Zlokarnik et al., 1998), which we adapted for the detection of Toxoplasma gondii secreted proteins. This assay revealed that the actin-binding protein toxofilin appears to be secreted into host cells during invasion. To determine the function of toxofilin during infection, we engineered a type I (RH strain) parasite with a targeted deletion of the toxofilin gene and compared the phenotypes of control and toxofilin knock-out (Deltatxf) parasites in several in vitro assays, including invasion, growth, and gliding motility, and egress of the Deltatxf parasites, as well as F-actin staining, phagocytosis and migration of cells infected with Deltatxf parasites or wild-type controls. Despite its apparent secretion into host cells and its ability to bind to and modulate host actin, we observed that toxofilin does not appear to play a role in these processes, under the conditions we examined, and we report these findings here.
PMID: 19732057 [PubMed - as supplied by publisher]
Fetal Infections and Brain Development
Clin Perinatol. 2009 Sep;36(3):639-653
Fetal Infections and Brain Development
Bale JF Jr.
Division of Pediatric Neurology, Departments of Pediatrics and Neurology, The University of Utah School of Medicine, Salt Lake City, UT 84158, USA; Pediatric Residency Office, Third Floor, Primary Children's Medical Center, 100 North Mario Capecchi Drive, PO Box 581289, Salt Lake City, UT 84113, USA.
Current microbial diagnostics enable rapid and specific identification of the agents causing intrauterine and perinatal infections, and CT and MRI allow precise characterization of the central nervous system effects of these pathogens. Although infections with Toxoplasma gondii, Toxoplasma pallidum, Toxoplasma cruzi, and cytomegalovirus cannot currently be prevented by immunization, postnatal therapy of infected neonates can substantially improve outcome. Therapy with acyclovir should be initiated whenever perinatal herpes simplex virus encephalitis is suspected. Despite these strategies, intrauterine and perinatal infections remain major causes of permanent deafness, vision loss, cerebral palsy, and epilepsy among children throughout the world.
PMID: 19732618 [PubMed - as supplied by publisher]
Fetal Infections and Brain Development
Bale JF Jr.
Division of Pediatric Neurology, Departments of Pediatrics and Neurology, The University of Utah School of Medicine, Salt Lake City, UT 84158, USA; Pediatric Residency Office, Third Floor, Primary Children's Medical Center, 100 North Mario Capecchi Drive, PO Box 581289, Salt Lake City, UT 84113, USA.
Current microbial diagnostics enable rapid and specific identification of the agents causing intrauterine and perinatal infections, and CT and MRI allow precise characterization of the central nervous system effects of these pathogens. Although infections with Toxoplasma gondii, Toxoplasma pallidum, Toxoplasma cruzi, and cytomegalovirus cannot currently be prevented by immunization, postnatal therapy of infected neonates can substantially improve outcome. Therapy with acyclovir should be initiated whenever perinatal herpes simplex virus encephalitis is suspected. Despite these strategies, intrauterine and perinatal infections remain major causes of permanent deafness, vision loss, cerebral palsy, and epilepsy among children throughout the world.
PMID: 19732618 [PubMed - as supplied by publisher]
Sunday, September 06, 2009
Toxoplasma gondii: Prototype immunization of lambs against formation of muscle and brain cysts
Vet Parasitol. 2009 Aug 15. [Epub ahead of print]
Toxoplasma gondii: Prototype immunization of lambs against formation of muscle and brain cysts
Falcón J, Freyre A.
Laboratory for Toxoplasmosis, Dept. Parasitology, College of Veterinary Sciences, Montevideo, Uruguay.
Nine lambs were immunized with 10(6) oocysts of the relatively avirulent ME-49 strain of Toxoplasma gondii, and were challenged 45 days later with 4x10(6) oocysts of the M3 strain of this parasite. Less than 5 tissue cysts of the M3 strain formed per 8g of muscle - if any - judging from a bioassay in mice in which all mice survived. In contrast, mortality occurred in mice fed muscle specimens from 4 lambs that had not been immunized with ME-49 prior to challenge with the M3 strain. This finding suggests the possibility of creating a vaccine for lambs that could diminish or abolish lamb and mutton as sources of human infection with T. gondii, and which could also prevent toxoplasmosis abortion in sheep.
PMID: 19729248 [PubMed - as supplied by publisher]
Toxoplasma gondii: Prototype immunization of lambs against formation of muscle and brain cysts
Falcón J, Freyre A.
Laboratory for Toxoplasmosis, Dept. Parasitology, College of Veterinary Sciences, Montevideo, Uruguay.
Nine lambs were immunized with 10(6) oocysts of the relatively avirulent ME-49 strain of Toxoplasma gondii, and were challenged 45 days later with 4x10(6) oocysts of the M3 strain of this parasite. Less than 5 tissue cysts of the M3 strain formed per 8g of muscle - if any - judging from a bioassay in mice in which all mice survived. In contrast, mortality occurred in mice fed muscle specimens from 4 lambs that had not been immunized with ME-49 prior to challenge with the M3 strain. This finding suggests the possibility of creating a vaccine for lambs that could diminish or abolish lamb and mutton as sources of human infection with T. gondii, and which could also prevent toxoplasmosis abortion in sheep.
PMID: 19729248 [PubMed - as supplied by publisher]
Wednesday, September 02, 2009
Reporter genes facilitating discovery of drugs targeting protozoan parasites
Trends Parasitol. 2009 Aug 29. [Epub ahead of print]
Reporter genes facilitating discovery of drugs targeting protozoan parasites
Dube A, Gupta R, Singh N.
Division of Parasitology, Central Drug Research Institute, Lucknow 226 001, India.
Transfection of protozoan parasites, such as Plasmodium, Leishmania, Trypanosoma and Toxoplasma, with various reporter gene constructs, has revolutionized studies to understand the biology of the host-parasite interactions at the cellular level. It has provided impetus to the development of rapid and reliable drug screens both for established drugs and for new molecules against different parasites and other pathogens. Furthermore, reporter genes have proved to be an excellent and promising tool for studying disease progression. Here, we review the recent advances made by using reporter genes for in vitro and in vivo drug screening, high-throughput screening, whole-animal non-invasive imaging for parasites and for the study of several aspects of host-parasite interactions.
PMID: 19720564 [PubMed - as supplied by publisher]
Reporter genes facilitating discovery of drugs targeting protozoan parasites
Dube A, Gupta R, Singh N.
Division of Parasitology, Central Drug Research Institute, Lucknow 226 001, India.
Transfection of protozoan parasites, such as Plasmodium, Leishmania, Trypanosoma and Toxoplasma, with various reporter gene constructs, has revolutionized studies to understand the biology of the host-parasite interactions at the cellular level. It has provided impetus to the development of rapid and reliable drug screens both for established drugs and for new molecules against different parasites and other pathogens. Furthermore, reporter genes have proved to be an excellent and promising tool for studying disease progression. Here, we review the recent advances made by using reporter genes for in vitro and in vivo drug screening, high-throughput screening, whole-animal non-invasive imaging for parasites and for the study of several aspects of host-parasite interactions.
PMID: 19720564 [PubMed - as supplied by publisher]
Galectin-3 plays a modulatory role in the life span and activation of murine neutrophils
Immunobiology. 2009 Aug 29. [Epub ahead of print]
Galectin-3 plays a modulatory role in the life span and activation of murine neutrophils during early Toxoplasma gondii infection
Alves CM, Silva DA, Azzolini AE, Marzocchi-Machado CM, Carvalho JV, Pajuaba AC, Lucisano-Valim YM, Chammas R, Liu FT, Roque-Barreira MC, Mineo JR.
Laboratory of Immunoparasitology, Institute of Biomedical Sciences, Universidade Federal de Uberlândia, Uberlândia, Brazil.
Galectins are beta-galactoside-binding lectins involved in several biological processes and galectin-3 (Gal-3) is related to modulation of immune and inflammatory responses. This study aimed to evaluate the role of Gal-3 in the life span and biological functions of murine neutrophils during in vitro infection by virulent Toxoplasma gondii RH strain. Inflammatory peritoneal neutrophils (Nphi) from C57BL/6 wild-type (WT) and Gal-3 knockout (KO) mice were cultured in the presence or absence of parasites and analyzed for phosphatidylserine (PS) exposure and cell death using Annexin-V and propidium iodide staining, and cell viability by MTT assay. Cell toxicities determined by lactate dehydrogenase (LDH), degranulation by lysozyme release, and cytokine production were measured in Nphi culture supernatants. Phorbol myristate acetate (PMA)- or zymosan-dependent reactive oxygen species (ROS) were measured in Nphi cultures. Our results demonstrated that Gal-3 is involved in the increase of the viable Nphi number and the decrease of PS exposure and cell death following T. gondii infection. We also observed that Gal-3 downmodulates T. gondii-induced Nphi toxicity as well as Nphi degranulation regardless of infection. Furthermore, Gal-3 expression by Nphi was associated with increased levels of IL-10 in the beginning and decreased levels of TNF-alpha later on, regardless of parasite infection, as well as with decreased levels of IL-6 and increased IL-12 levels, following early parasite infection. Our results also showed that Gal-3 suppresses PMA- but not zymosan-induced ROS generation in Nphi following T. gondii infection. In conclusion, Gal-3 plays an important modulatory role by interfering in Nphi life span and activation during early T. gondii infection.
PMID: 19720428 [PubMed - as supplied by publisher]
Galectin-3 plays a modulatory role in the life span and activation of murine neutrophils during early Toxoplasma gondii infection
Alves CM, Silva DA, Azzolini AE, Marzocchi-Machado CM, Carvalho JV, Pajuaba AC, Lucisano-Valim YM, Chammas R, Liu FT, Roque-Barreira MC, Mineo JR.
Laboratory of Immunoparasitology, Institute of Biomedical Sciences, Universidade Federal de Uberlândia, Uberlândia, Brazil.
Galectins are beta-galactoside-binding lectins involved in several biological processes and galectin-3 (Gal-3) is related to modulation of immune and inflammatory responses. This study aimed to evaluate the role of Gal-3 in the life span and biological functions of murine neutrophils during in vitro infection by virulent Toxoplasma gondii RH strain. Inflammatory peritoneal neutrophils (Nphi) from C57BL/6 wild-type (WT) and Gal-3 knockout (KO) mice were cultured in the presence or absence of parasites and analyzed for phosphatidylserine (PS) exposure and cell death using Annexin-V and propidium iodide staining, and cell viability by MTT assay. Cell toxicities determined by lactate dehydrogenase (LDH), degranulation by lysozyme release, and cytokine production were measured in Nphi culture supernatants. Phorbol myristate acetate (PMA)- or zymosan-dependent reactive oxygen species (ROS) were measured in Nphi cultures. Our results demonstrated that Gal-3 is involved in the increase of the viable Nphi number and the decrease of PS exposure and cell death following T. gondii infection. We also observed that Gal-3 downmodulates T. gondii-induced Nphi toxicity as well as Nphi degranulation regardless of infection. Furthermore, Gal-3 expression by Nphi was associated with increased levels of IL-10 in the beginning and decreased levels of TNF-alpha later on, regardless of parasite infection, as well as with decreased levels of IL-6 and increased IL-12 levels, following early parasite infection. Our results also showed that Gal-3 suppresses PMA- but not zymosan-induced ROS generation in Nphi following T. gondii infection. In conclusion, Gal-3 plays an important modulatory role by interfering in Nphi life span and activation during early T. gondii infection.
PMID: 19720428 [PubMed - as supplied by publisher]
MIC6 is a potential vaccine candidate against toxoplasmosis in mice
Vaccine. 2009 Aug 28. [Epub ahead of print]
Toxoplasma gondii microneme protein 6 (MIC6) is a potential vaccine candidate against toxoplasmosis in mice
Peng GH, Yuan ZG, Zhou DH, He XH, Liu MM, Yan C, Yin CC, He Y, Lin RQ, Zhu XQ.
Department of Parasitology, College of Veterinary Medicine, South China Agricultural University, 483 Wushan Street, Tianhe District, Guangzhou, Guangdong Province 510642, People's Republic of China.
Infection with the intracellular protozoan parasite Toxoplasma gondii causes serious public health problems and is of great economic importance worldwide. Microneme proteins which are responsible for adhesion and invasion have been implicated as vaccine candidates. In this study, we constructed a DNA vaccine expressing microneme protein 6 (MIC6) of T. gondii, and evaluated the immune response it induced in Kunming mice. The gene sequence encoding MIC6 was inserted into the eukaryotic expression vector pVAXI. We immunized Kunming mice intramuscularly. After immunization, we evaluated the immune response using lymphoproliferative assay, cytokine and antibody measurements, and the survival times of mice challenged lethally. The results showed that the group immunized with pVAX-MIC6 developed a high level of specific antibody responses against T. gondii lysate antigen (TLA), a strong lymphoproliferative response, and significant levels of IFN-gamma, IL-2, IL-4 and IL-10 production, compared with the other groups immunized with empty plasmid or phosphate-buffered saline, respectively. These results demonstrate that pVAX-MIC6 induces significant humoral and cellular Th1 immune responses. After lethal challenge, the mice immunized with the pVAX-MIC6 showed an increased survival time (13.3+/-1.2 days) compared with control mice died within 7 days of challenge. Our data demonstrate, for the first time, that MIC6 triggered a strong humoral and cellular response against T. gondii, and that the antigen is a potential vaccine candidate against toxoplasmosis, worth further development.
PMID: 19720368 [PubMed - as supplied by publisher]
Toxoplasma gondii microneme protein 6 (MIC6) is a potential vaccine candidate against toxoplasmosis in mice
Peng GH, Yuan ZG, Zhou DH, He XH, Liu MM, Yan C, Yin CC, He Y, Lin RQ, Zhu XQ.
Department of Parasitology, College of Veterinary Medicine, South China Agricultural University, 483 Wushan Street, Tianhe District, Guangzhou, Guangdong Province 510642, People's Republic of China.
Infection with the intracellular protozoan parasite Toxoplasma gondii causes serious public health problems and is of great economic importance worldwide. Microneme proteins which are responsible for adhesion and invasion have been implicated as vaccine candidates. In this study, we constructed a DNA vaccine expressing microneme protein 6 (MIC6) of T. gondii, and evaluated the immune response it induced in Kunming mice. The gene sequence encoding MIC6 was inserted into the eukaryotic expression vector pVAXI. We immunized Kunming mice intramuscularly. After immunization, we evaluated the immune response using lymphoproliferative assay, cytokine and antibody measurements, and the survival times of mice challenged lethally. The results showed that the group immunized with pVAX-MIC6 developed a high level of specific antibody responses against T. gondii lysate antigen (TLA), a strong lymphoproliferative response, and significant levels of IFN-gamma, IL-2, IL-4 and IL-10 production, compared with the other groups immunized with empty plasmid or phosphate-buffered saline, respectively. These results demonstrate that pVAX-MIC6 induces significant humoral and cellular Th1 immune responses. After lethal challenge, the mice immunized with the pVAX-MIC6 showed an increased survival time (13.3+/-1.2 days) compared with control mice died within 7 days of challenge. Our data demonstrate, for the first time, that MIC6 triggered a strong humoral and cellular response against T. gondii, and that the antigen is a potential vaccine candidate against toxoplasmosis, worth further development.
PMID: 19720368 [PubMed - as supplied by publisher]
Simple Real-time PCR assay to quantify the proliferation of the apicoplast
Exp Parasitol. 2009 Aug 28. [Epub ahead of print]
Toxoplasma gondii: a simple Real-time PCR assay to quantify the proliferation of the apicoplast
Wu L, Chen SX, Jiang XG, Cao JP.
School of Medical Technology, Jiangsu University, Zhenjiang, People's Republic of China.
A Real-time quantitative PCR assay to quantify the Toxoplasma gondii apicoplast was studied. Primers were designed to amplify a 305 bp product specific to T. gondii apicoplast. Standard curves were generated for both T. gondii apicoplast DNA and genomic DNA, and were used to compute the relative concentration of apicoplast DNA copies in the test samples. The results indicated that the copies of T. gondii apicoplast DNA was significantly low when exposed to ciprofloxacin, clindamycin and azithromycin for 48 h in the second infectious cycle. Our study shows that the Real-time PCR technique is a simple and quick technique for screening the anti-apicoplast drugs.
PMID: 19720060 [PubMed - as supplied by publisher]
Toxoplasma gondii: a simple Real-time PCR assay to quantify the proliferation of the apicoplast
Wu L, Chen SX, Jiang XG, Cao JP.
School of Medical Technology, Jiangsu University, Zhenjiang, People's Republic of China.
A Real-time quantitative PCR assay to quantify the Toxoplasma gondii apicoplast was studied. Primers were designed to amplify a 305 bp product specific to T. gondii apicoplast. Standard curves were generated for both T. gondii apicoplast DNA and genomic DNA, and were used to compute the relative concentration of apicoplast DNA copies in the test samples. The results indicated that the copies of T. gondii apicoplast DNA was significantly low when exposed to ciprofloxacin, clindamycin and azithromycin for 48 h in the second infectious cycle. Our study shows that the Real-time PCR technique is a simple and quick technique for screening the anti-apicoplast drugs.
PMID: 19720060 [PubMed - as supplied by publisher]
2-Amino-4-oxo-5-substituted-6-ethylthieno[2,3-d]pyrimidines as Dual Thymidylate Synthase and Dihydrofolate Reductase Inhibitors
J Med Chem. 2009 Aug 13;52(15):4892-902
Design, Synthesis, and X-ray Crystal Structure of Classical and Nonclassical 2-Amino-4-oxo-5-substituted-6-ethylthieno[2,3-d]pyrimidines as Dual Thymidylate Synthase and Dihydrofolate Reductase Inhibitors and as Potential Antitumor Agents
Gangjee A, Li W, Kisliuk RL, Cody V, Pace J, Piraino J, Makin J.
Division of Medicinal Chemistry, Graduate School of Pharmaceutical Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282.
N-{4-[(2-Amino-6-ethyl-4-oxo-3,4-dihydrothieno[2,3-d]pyrimidin-5-yl)thio]benzoyl}-l-glutamic acid 2 and 13 nonclassical analogues 2a-2m were synthesized as potential dual thymidylate synthase (TS) and dihydrofolate reductase (DHFR) inhibitors and as antitumor agents. The key intermediate in the synthesis was 2-amino-6-ethyl-5-iodothieno[2,3-d]pyrimidin-4(3H)-one, 7, to which various arylthiols were attached at the 5-position. Coupling 8 with l-glutamic acid diethyl ester and saponification afforded 2. X-ray crystal structures of 2 and 1 (the 6-methyl analogue of 2), DHFR, and NADPH showed for the first time that the thieno[2,3-d]pyrimidine ring binds in a "folate" mode. Compound 2 was an excellent dual inhibitor of human TS (IC(50) = 54 nM) and human DHFR (IC(50) = 19 nM) and afforded nanomolar GI(50) values against tumor cells in culture. The 6-ethyl substitution in 2 increases both the potency (by 2-3 orders of magnitude) as well as the spectrum of tumor inhibition in vitro compared to the 6-methyl analogue 1. Some of the nonclassical analogues were potent and selective inhibitors of DHFR from Toxoplasma gondii.
PMID: 19719239 [PubMed - in process]
Design, Synthesis, and X-ray Crystal Structure of Classical and Nonclassical 2-Amino-4-oxo-5-substituted-6-ethylthieno[2,3-d]pyrimidines as Dual Thymidylate Synthase and Dihydrofolate Reductase Inhibitors and as Potential Antitumor Agents
Gangjee A, Li W, Kisliuk RL, Cody V, Pace J, Piraino J, Makin J.
Division of Medicinal Chemistry, Graduate School of Pharmaceutical Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282.
N-{4-[(2-Amino-6-ethyl-4-oxo-3,4-dihydrothieno[2,3-d]pyrimidin-5-yl)thio]benzoyl}-l-glutamic acid 2 and 13 nonclassical analogues 2a-2m were synthesized as potential dual thymidylate synthase (TS) and dihydrofolate reductase (DHFR) inhibitors and as antitumor agents. The key intermediate in the synthesis was 2-amino-6-ethyl-5-iodothieno[2,3-d]pyrimidin-4(3H)-one, 7, to which various arylthiols were attached at the 5-position. Coupling 8 with l-glutamic acid diethyl ester and saponification afforded 2. X-ray crystal structures of 2 and 1 (the 6-methyl analogue of 2), DHFR, and NADPH showed for the first time that the thieno[2,3-d]pyrimidine ring binds in a "folate" mode. Compound 2 was an excellent dual inhibitor of human TS (IC(50) = 54 nM) and human DHFR (IC(50) = 19 nM) and afforded nanomolar GI(50) values against tumor cells in culture. The 6-ethyl substitution in 2 increases both the potency (by 2-3 orders of magnitude) as well as the spectrum of tumor inhibition in vitro compared to the 6-methyl analogue 1. Some of the nonclassical analogues were potent and selective inhibitors of DHFR from Toxoplasma gondii.
PMID: 19719239 [PubMed - in process]
Subscribe to:
Posts (Atom)