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Li M, Mo XW, Wang L, Chen H, Luo QL, Wen HQ, Wei W, Zhang AM, Du J, Lu FL, Lun ZR, Shen JL. Phylogeny and virulence divergency analyses of Toxoplasma gondii isolates from China. Parasit Vectors 2014; 7:133. [PMID: 24678633 PMCID: PMC3986613 DOI: 10.1186/1756-3305-7-133] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 03/11/2014] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Toxoplasma gondii (T. gondii) is a very successful parasite that can infect virtually all warm blooded animals with a worldwide distribution. It causes a large range of clinical manifestations in both humans and domesticated animals. In addition, marked biological differences exist among T. gondii strains in the pathogenicity and geographical distribution. Molecular epidemiology studies primarily based on restriction fragment length polymorphism (RFLP) method revealed that three main types are predominant in North America and Europe, whereas other diverse genotypes are found in other parts of the world. Microsatellite (MS) as a type of genetic marker has been widely used in many organisms. Limited MS genotyping, however, to fingerprint T. gondii isolates has been reported and little is known about the MS data of the strains predominantly prevalent in China. METHODS Genotyping of twenty-eight Chinese T. gondii isolates were performed using 15 MS markers located on 12 different chromosomes. Results were analyzed in terms of population structure by a Bayesian statistical approach. Phylogenetic analysis was obtained from a Neighbor-Net phylogenetic network. The virulence analyses of some representative isolates were determined by inoculation of mice and cell invasion assays. The gene expressions of some virulence-associated factors (VFs) were performed by quantitative real-time PCR (qRT- PCR). RESULTS Three haplogroups were clustered among the 28 isolates although minor genetic differences were found within haplogroups. The majority of strains belong to one haplogroup corresponding to the previously described Chinese 1 type (ToxoDB#9). Phylogenetic networks uncovered a limited diversity of T. gondii strains and the virulence differs in the strains sharing the same genotype. No remarkable difference, however, was noted in the tested VFs except for dense granule protein3 (GRA3), which was found to have a higher expression in low virulent TgCtwh6 (Wh6) strain than that in high virulent TgCtwh3 (Wh3) strain. CONCLUSION The profile of microsatellite typing data from Chinese T. gondii strains revealed a limited genetic diversity and the selected VFs and phylogenetic network analyses displayed less divergence, although the strain virulence differs in the Chinese 1 type of T. gondii predominantly prevalent in China.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Ji-Long Shen
- Anhui Provincial Laboratories of Pathogen Biology and Zoonoses, Department of Microbiology and Parasitology, Anhui Medical University, Hefei, Anhui, China.
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152
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Ocular toxoplasmosis past, present and new aspects of an old disease. Prog Retin Eye Res 2014; 39:77-106. [DOI: 10.1016/j.preteyeres.2013.12.005] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 12/19/2013] [Accepted: 12/27/2013] [Indexed: 12/22/2022]
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153
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Niehus S, Smith TK, Azzouz N, Campos MA, Dubremetz JF, Gazzinelli RT, Schwarz RT, Debierre-Grockiego F. Virulent and avirulent strains of Toxoplasma gondii which differ in their glycosylphosphatidylinositol content induce similar biological functions in macrophages. PLoS One 2014; 9:e85386. [PMID: 24489660 PMCID: PMC3904843 DOI: 10.1371/journal.pone.0085386] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 11/26/2013] [Indexed: 11/18/2022] Open
Abstract
Glycosylphosphatidylinositols (GPIs) from several protozoan parasites are thought to elicit a detrimental stimulation of the host innate immune system aside their main function to anchor surface proteins. Here we analyzed the GPI biosynthesis of an avirulent Toxoplasma gondii type 2 strain (PTG) by metabolic radioactive labeling. We determined the biological function of individual GPI species in the PTG strain in comparison with previously characterized GPI-anchors of a virulent strain (RH). The GPI intermediates of both strains were structurally similar, however the abundance of two of six GPI intermediates was significantly reduced in the PTG strain. The side-by-side comparison of GPI-anchor content revealed that the PTG strain had only ∼34% of the protein-free GPIs as well as ∼70% of the GPI-anchored proteins with significantly lower rates of protein N-glycosylation compared to the RH strain. All mature GPIs from both strains induced comparable secretion levels of TNF-α and IL-12p40, and initiated TLR4/MyD88-dependent NF-κBp65 activation in macrophages. Taken together, these results demonstrate that PTG and RH strains differ in their GPI biosynthesis and possess significantly different GPI-anchor content, while individual GPI species of both strains induce similar biological functions in macrophages.
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Affiliation(s)
- Sebastian Niehus
- Institute for Virology, Laboratory of Parasitology, Philipps-University, Marburg, Germany
- UPR 9022 CNRS, Institute of Molecular and Cellular Biology, Strasbourg, France
- * E-mail:
| | - Terry K. Smith
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, United Kingdom
| | - Nahid Azzouz
- Institute for Virology, Laboratory of Parasitology, Philipps-University, Marburg, Germany
| | - Marco A. Campos
- Research Center René Rachou, Oswaldo Cruz Foundation, Laboratory of Immunopathology, Belo Horizonte, Brazil
| | | | - Ricardo T. Gazzinelli
- Research Center René Rachou, Oswaldo Cruz Foundation, Laboratory of Immunopathology, Belo Horizonte, Brazil
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Ralph T. Schwarz
- Institute for Virology, Laboratory of Parasitology, Philipps-University, Marburg, Germany
- UMR 8576 CNRS, Unit of Structural and Functional Glycobiology, University of, Lille, France
| | - Françoise Debierre-Grockiego
- Institute for Virology, Laboratory of Parasitology, Philipps-University, Marburg, Germany
- UMR 1282 Infectiology and Public Health, University of Tours, Tours, France and INRA, Nouzilly, France
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154
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Moncada PA, Montoya JG. Toxoplasmosis in the fetus and newborn: an update on prevalence, diagnosis and treatment. Expert Rev Anti Infect Ther 2014; 10:815-28. [DOI: 10.1586/eri.12.58] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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155
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Dubey J, Ness S, Kwok O, Choudhary S, Mittel L, Divers T. Seropositivity of Toxoplasma gondii in domestic donkeys (Equus asinus) and isolation of T. gondii from farm cats. Vet Parasitol 2014; 199:18-23. [DOI: 10.1016/j.vetpar.2013.09.027] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 09/23/2013] [Accepted: 09/23/2013] [Indexed: 01/29/2023]
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156
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Melo MB, Nguyen QP, Cordeiro C, Hassan MA, Yang N, McKell R, Rosowski EE, Julien L, Butty V, Dardé ML, Ajzenberg D, Fitzgerald K, Young LH, Saeij JPJ. Transcriptional analysis of murine macrophages infected with different Toxoplasma strains identifies novel regulation of host signaling pathways. PLoS Pathog 2013; 9:e1003779. [PMID: 24367253 PMCID: PMC3868521 DOI: 10.1371/journal.ppat.1003779] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 09/18/2013] [Indexed: 11/19/2022] Open
Abstract
Most isolates of Toxoplasma from Europe and North America fall into one of three genetically distinct clonal lineages, the type I, II and III lineages. However, in South America these strains are rarely isolated and instead a great variety of other strains are found. T. gondii strains differ widely in a number of phenotypes in mice, such as virulence, persistence, oral infectivity, migratory capacity, induction of cytokine expression and modulation of host gene expression. The outcome of toxoplasmosis in patients is also variable and we hypothesize that, besides host and environmental factors, the genotype of the parasite strain plays a major role. The molecular basis for these differences in pathogenesis, especially in strains other than the clonal lineages, remains largely unexplored. Macrophages play an essential role in the early immune response against T. gondii and are also the cell type preferentially infected in vivo. To determine if non-canonical Toxoplasma strains have unique interactions with the host cell, we infected murine macrophages with 29 different Toxoplasma strains, representing global diversity, and used RNA-sequencing to determine host and parasite transcriptomes. We identified large differences between strains in the expression level of known parasite effectors and large chromosomal structural variation in some strains. We also identified novel strain-specifically regulated host pathways, including the regulation of the type I interferon response by some atypical strains. IFNβ production by infected cells was associated with parasite killing, independent of interferon gamma activation, and dependent on endosomal Toll-like receptors in macrophages and the cytoplasmic receptor retinoic acid-inducible gene 1 (RIG-I) in fibroblasts.
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Affiliation(s)
- Mariane B. Melo
- Massachusetts Institute of Technology, Department of Biology, Cambridge, Massachusetts, United States of America
| | - Quynh P. Nguyen
- Massachusetts Institute of Technology, Department of Biology, Cambridge, Massachusetts, United States of America
| | - Cynthia Cordeiro
- Massachusetts Institute of Technology, Department of Biology, Cambridge, Massachusetts, United States of America
- Internal Medicine Department, School of Medicine, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
- Retina Service, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Musa A. Hassan
- Massachusetts Institute of Technology, Department of Biology, Cambridge, Massachusetts, United States of America
| | - Ninghan Yang
- Massachusetts Institute of Technology, Department of Biology, Cambridge, Massachusetts, United States of America
| | - Renée McKell
- Massachusetts Institute of Technology, Department of Biology, Cambridge, Massachusetts, United States of America
| | - Emily E. Rosowski
- Massachusetts Institute of Technology, Department of Biology, Cambridge, Massachusetts, United States of America
| | - Lindsay Julien
- Massachusetts Institute of Technology, Department of Biology, Cambridge, Massachusetts, United States of America
| | - Vincent Butty
- Massachusetts Institute of Technology, Department of Biology, Cambridge, Massachusetts, United States of America
| | - Marie-Laure Dardé
- Centre National de Référence Toxoplasmose/Toxoplasma Biological Resource Center, Centre Hospitalier-Universitaire Dupuytren, Limoges, France
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 1094, Neuroépidémiologie Tropicale, Laboratoire de Parasitologie-Mycologie, Faculté de Médecine, Université de Limoges, Limoges, France
| | - Daniel Ajzenberg
- Centre National de Référence Toxoplasmose/Toxoplasma Biological Resource Center, Centre Hospitalier-Universitaire Dupuytren, Limoges, France
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 1094, Neuroépidémiologie Tropicale, Laboratoire de Parasitologie-Mycologie, Faculté de Médecine, Université de Limoges, Limoges, France
| | - Katherine Fitzgerald
- University of Massachusetts Medical School, Division of Infectious Diseases and Immunology, Worcester, Massachusetts, United States of America
| | - Lucy H. Young
- Retina Service, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jeroen P. J. Saeij
- Massachusetts Institute of Technology, Department of Biology, Cambridge, Massachusetts, United States of America
- * E-mail:
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157
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Geographical patterns of Toxoplasma gondii genetic diversity revealed by multilocus PCR-RFLP genotyping. Parasitology 2013; 141:453-61. [PMID: 24477076 DOI: 10.1017/s0031182013001844] [Citation(s) in RCA: 305] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In recent years, an extensive collection of Toxoplasma gondii samples have been typed using a set of 10 PCR-RFLP genetic markers. Here we summarize the data reported until the end of 2012. A total of 1457 samples were typed into 189 genotypes. Overall, only a few genotypes dominate in the northern hemisphere, which is in stark contrast to the southern hemisphere where hundreds of genotypes coexist with none being notably dominant. PCR-RFLP genotype #1 (Type II clonal), #2 (Type III), #3 (Type II variant) and #10 (Type I) are identified globally. Genotypes #2 and #3 dominate in Africa, genotypes #9 (Chinese 1) and #10 are prevalent in Asia, genotypes #1, #2 and #3 are prevalent in Europe, genotypes #1, #2, #3, #4 and #5 dominate in North America (#4 and #5 are collectively known as Type 12). In Central and South America, there is no clear dominance of any genotype even though a few have relatively higher frequencies. Statistical analysis indicates significant differences among populations in Africa, Asia, Europe, North America, and Central and South America, with only Europe and North America exhibiting similar diversity. Collectively, the results revealed distinct population structures and geographical patterns of diversity in T. gondii.
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158
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Zhou DH, Zhao FR, Nisbet AJ, Xu MJ, Song HQ, Lin RQ, Huang SY, Zhu XQ. Comparative proteomic analysis of differentToxoplasma gondiigenotypes by two-dimensional fluorescence difference gel electrophoresis combined with mass spectrometry. Electrophoresis 2013; 35:533-45. [DOI: 10.1002/elps.201300044] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2013] [Revised: 08/30/2013] [Accepted: 10/10/2013] [Indexed: 12/12/2022]
Affiliation(s)
- Dong-Hui Zhou
- State Key Laboratory of Veterinary Etiological Biology; Key Laboratory of Veterinary Parasitology of Gansu Province; Lanzhou Veterinary Research Institute; Chinese Academy of Agricultural Sciences; Lanzhou Gansu Province P. R. China
| | - Fu-Rong Zhao
- State Key Laboratory of Veterinary Etiological Biology; Key Laboratory of Veterinary Parasitology of Gansu Province; Lanzhou Veterinary Research Institute; Chinese Academy of Agricultural Sciences; Lanzhou Gansu Province P. R. China
| | - Alasdair J. Nisbet
- Vaccines and Diagnostics, Moredun Research Institute; Pentlands Science Park; Scotland UK
| | - Min-Jun Xu
- State Key Laboratory of Veterinary Etiological Biology; Key Laboratory of Veterinary Parasitology of Gansu Province; Lanzhou Veterinary Research Institute; Chinese Academy of Agricultural Sciences; Lanzhou Gansu Province P. R. China
| | - Hui-Qun Song
- State Key Laboratory of Veterinary Etiological Biology; Key Laboratory of Veterinary Parasitology of Gansu Province; Lanzhou Veterinary Research Institute; Chinese Academy of Agricultural Sciences; Lanzhou Gansu Province P. R. China
| | - Rui-Qing Lin
- College of Veterinary Medicine; South China Agricultural University; Guangzhou Guangdong Province P. R. China
| | - Si-Yang Huang
- State Key Laboratory of Veterinary Etiological Biology; Key Laboratory of Veterinary Parasitology of Gansu Province; Lanzhou Veterinary Research Institute; Chinese Academy of Agricultural Sciences; Lanzhou Gansu Province P. R. China
| | - Xing-Quan Zhu
- State Key Laboratory of Veterinary Etiological Biology; Key Laboratory of Veterinary Parasitology of Gansu Province; Lanzhou Veterinary Research Institute; Chinese Academy of Agricultural Sciences; Lanzhou Gansu Province P. R. China
- College of Animal Science and Veterinary Medicine; Heilongjiang Bayi Agricultural University; Daqing Heilongjiang Province P. R. China
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159
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Dubey JP, Van Why K, Verma SK, Choudhary S, Kwok OCH, Khan A, Behinke MS, Sibley LD, Ferreira LR, Oliveira S, Weaver M, Stewart R, Su C. Genotyping Toxoplasma gondii from wildlife in Pennsylvania and identification of natural recombinants virulent to mice. Vet Parasitol 2013; 200:74-84. [PMID: 24332401 DOI: 10.1016/j.vetpar.2013.11.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 10/30/2013] [Accepted: 11/01/2013] [Indexed: 11/24/2022]
Abstract
Recent studies indicated the predominance of Toxoplasma gondii haplogroup 12 in wildlife in the USA. However, still little is known of the genetic diversity of this parasite circulating in wildlife. In the present study, we tested coyotes (Canis latrans), red foxes (Vulpes vulpes), white-tailed deer (Odocoileus virginianus), and geese (Branta canadensis) from the state of Pennsylvania for T. gondii infection. Antibodies to T. gondii were found in 160 of 367 animals, including 92 (34.5%) of 266 coyotes, 49 (62.0%) of 79 white-tailed deer, 17 (85.0%) of 20 red fox, and two of two Canada geese tested by the modified agglutination test (cut off titer 1:25). Tissues from 105 seropositive animals were bioassayed in mice, and viable T. gondii was isolated from 29 animals, including 10 of 53 coyotes, 11 of 16 foxes, 7 of 49 deer, and one of one goose. DNA isolated from culture-derived tachyzoites of these isolates was characterized initially using multilocus PCR-RFLP markers. Nine genotypes were revealed, including ToxoDB PCR-RFLP #1 (4 isolates), #2 (2 isolates), #3 (4 isolates), #4 (6 isolates), #5 (4 isolates), #54 (1 isolate), #141 (1 isolate), #143 (1 isolate), and #216 (6 isolates), indicating high genetic diversity of T. gondii in wildlife in Pennsylvania. Pathogenicity of six T. gondii isolates (5 of #216 and #141) was determined in outbred Swiss Webster mice. Three of #216 and the #141 isolates were acute virulent to mice, and the other 2 #216 isolates were intermediate virulent. To determine the extent of genetic variation of these as well as a few recently reported virulent isolates from wildlife in North America, intron sequences were generated. Analysis of intron sequences and PCR-RFLP genotyping results indicated that the #216 isolates are likely derived from recombination of the clonal type I and III lineages. To determine if T. gondii virulence can be predicted by typing, we genotyped a collection of strains using PCR-RFLP markers for polymorphic genes ROP5, ROP16, ROP18 and GRA15, which are known to interact with host immune response. The results showed that there is an association of genotypes of ROP5 and ROP18 with mouse-virulence, however, additional gene(s) may also contribute to virulence in distinct T. gondii genotypes.
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Affiliation(s)
- J P Dubey
- United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Building 1001, Beltsville, MD 20705-2350, USA.
| | - K Van Why
- United States Department of Agriculture, Animal Plant Health Inspection Service, Wildlife Services, Harrisburg, PA 17106-0827, USA
| | - S K Verma
- United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Building 1001, Beltsville, MD 20705-2350, USA
| | - S Choudhary
- United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Building 1001, Beltsville, MD 20705-2350, USA
| | - O C H Kwok
- United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Building 1001, Beltsville, MD 20705-2350, USA
| | - A Khan
- Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - M S Behinke
- Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - L D Sibley
- Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - L R Ferreira
- United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Building 1001, Beltsville, MD 20705-2350, USA
| | - S Oliveira
- United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Building 1001, Beltsville, MD 20705-2350, USA
| | - M Weaver
- Department of Biology, College of Arts and Sciences, Shippensburg University, Shippensburg, PA 17257, USA
| | - R Stewart
- Department of Biology, College of Arts and Sciences, Shippensburg University, Shippensburg, PA 17257, USA
| | - C Su
- Department of Microbiology, The University of Tennessee, Knoxville, TN 37996-0845, USA
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160
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Dubey J, Alvarado-Esquivel C, Herrera-Valenzuela V, Ortiz-Diaz J, Oliveira S, Verma S, Choudhary S, Kwok O, Su C. A new atypical genotype mouse virulent strain of Toxoplasma gondii isolated from the heart of a wild caught puma (Felis concolor) from Durango, Mexico. Vet Parasitol 2013; 197:674-7. [DOI: 10.1016/j.vetpar.2013.06.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 05/23/2013] [Accepted: 06/03/2013] [Indexed: 11/16/2022]
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161
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Isolation and RFLP genotyping of Toxoplasma gondii from the gray wolf (Canis lupus). Vet Parasitol 2013; 197:685-90. [DOI: 10.1016/j.vetpar.2013.05.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 04/23/2013] [Accepted: 05/11/2013] [Indexed: 11/24/2022]
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162
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Dubey J, Tiwari K, Chikweto A, DeAllie C, Sharma R, Thomas D, Choudhary S, Ferreira L, Oliveira S, Verma S, Kwok O, Su C. Isolation and RFLP genotyping of Toxoplasma gondii from the domestic dogs (Canis familiaris) from Grenada, West Indies revealed high genetic variability. Vet Parasitol 2013; 197:623-6. [DOI: 10.1016/j.vetpar.2013.07.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 07/16/2013] [Accepted: 07/20/2013] [Indexed: 02/04/2023]
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163
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Cañón-Franco W, Araújo F, López-Orozco N, Jardim M, Keid L, Dalla-Rosa C, Cabral A, Pena H, Gennari S. Toxoplasma gondii in free-ranging wild small felids from Brazil: Molecular detection and genotypic characterization. Vet Parasitol 2013; 197:462-9. [DOI: 10.1016/j.vetpar.2013.07.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 07/01/2013] [Accepted: 07/12/2013] [Indexed: 01/25/2023]
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164
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Zhang AM, Shen Q, Li M, Xu XC, Chen H, Cai YH, Luo QL, Chu DY, Yu L, Du J, Lun ZR, Wang Y, Sha Q, Shen JL. Comparative studies of macrophage-biased responses in mice to infection with Toxoplasma gondii ToxoDB #9 strains of different virulence isolated from China. Parasit Vectors 2013; 6:308. [PMID: 24499603 PMCID: PMC4029513 DOI: 10.1186/1756-3305-6-308] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 10/22/2013] [Indexed: 11/25/2022] Open
Abstract
Background Different from three clonal lineages of Toxoplasma gondii in North America and Europe, the genotype China 1 is predominantly prevalent in China. However, there are different virulent isolates within China 1, such as virulent TgCtwh3 and avirulent TgCtwh6, and little is known about differences in macrophage activation between them. The objective of this study focused on cytokine production, phenotype and markers of activated macrophages, and correlated signaling pathway induced by the two isolates. Methods Adherent peritoneal macrophages (termed Wh3-Mφ and Wh6-Mφ, respectively) harvested from infected mice were cultured for detection of Nitric Oxide and arginase activity, and activated markers on Wh3-Mφ/Wh6-Mφ were determined by flow cytometry. In in vitro experiments, the levels of IL-12p40 and TNF-α were measured using ELISA kits, and mRNA expressions of IL-12p40, TNF-α, iNOS, Arg-1 and Ym1 were assayed by real-time PCR. To confirm the activation state of NF-kB p65 in infected cells stained by IF, protein levels of iNOS, Arg-1, Ym1, nuclear NF-κB p65, and phosphorylation of STAT6/STAT3/IκBα were evaluated by Western Blotting. A one-way ANOVA test was used to compare differences among multiple groups. Results The result revealed that contrary to the virulent TgCtwh3, the less virulent TgCtwh6 isolate induced a significant increase in IL-12p40 and TNF-α. Although both isolates down-regulated CD80, CD86 and MHCII molecule expression on macrophages, TgCtwh3 promoted up-regulation of PD-L2 and CD206. Wh6-Mφ generated a high level of NO whereas Wh3-Mφ up-regulated Ym1 and arginase expression at transcriptional and protein levels. In terms of signaling pathway, TgCtwh3 induced phospho-STAT6, conversely, TgCtWh6 led to NF-κB p65 activation. Conclusions The virulent TgCtwh3 isolate induced macrophages to polarize toward alternatively activated cells with STAT6 phosphorylation, whereas the less virulent TgCtwh6 elicited the development of classically activated macrophages with nuclear translocation of NF-κB p65. This discrepancy suggests that it is necessary to thoroughly analyze the genotype of TgCtwh3 and TgCtwh6, and to further study other effector molecules that contribute to the macrophage polarization in T. gondii.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | - Quan Sha
- Anhui Provincial Laboratories of Pathogen Biology and Zoonoses, Department of Microbiology and Parasitology, Anhui Medical University, Hefei, Anhui, China.
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165
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Zhang XX, Lou ZZ, Huang SY, Zhou DH, Jia WZ, Su C, Zhu XQ. Genetic characterization of Toxoplasma gondii from Qinghai vole, Plateau pika and Tibetan ground-tit on the Qinghai-Tibet Plateau, China. Parasit Vectors 2013; 6:291. [PMID: 24192458 PMCID: PMC3852027 DOI: 10.1186/1756-3305-6-291] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Accepted: 10/07/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The distribution of genetic diversity of Toxoplasma gondii in wildlife is of interest to understand the transmission of this parasite in the environment. Limited information on T. gondii genotypes has been reported in wildlife in China. The objective of this study was to carry out the genetic characterization of T. gondii isolates from wild animals on the Qinghai-Tibet Plateau. METHODS Using PCR and multilocous polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technology, we detected genetic diversity of T. gondii isolates from Qinghai vole, Plateau pika and Tibetan ground-tit in these regions. RESULTS In total, 183 brain tissues of different wild animals, including 48 Qinghai vole (Microtus fuscus), 101 Plateau pika (Ochotona curzoniae) and 34 Tibetan ground-tit (Pseudopodoces humilis), were tested for T. gondii infection. 11 of these were found to be positive for the T. gondii B1 gene by PCR amplification. These positive DNA samples were typed at 10 genetic markers, including 9 nuclear loci (SAG1, 5'-and 3'-SAG2, alternative SAG2, BTUB, GRA6, L358, PK1, c22-8, c29-2), and an apicoplast locus Apico. Six were successfully genotyped at eight or more genetic loci, and were grouped to three distinct genotypes. Four samples belonged to ToxoDB Genotype #10 and the other two samples were identified as two new genotypes (http://toxodb.org/toxo/). CONCLUSIONS To our knowledge, this is the first report of genetic typing of T. gondii isolates in wildlife on the Qinghai-Tibet Plateau, China. The results show that there is a potential risk for the transmission of this parasite through the wildlife in this region.
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Affiliation(s)
| | | | - Si-Yang Huang
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, PR China.
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It is not only the cat that did it: how to prevent and treat congenital toxoplasmosis. J Infect 2013; 68 Suppl 1:S125-33. [PMID: 24119928 DOI: 10.1016/j.jinf.2013.09.023] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2013] [Indexed: 11/22/2022]
Abstract
The apicomplexan parasite Toxoplasma gondii was discovered a little over one hundred years ago and was soon recognized as a pathogen responsible for congenital infection. But detailed understanding of its epidemiology emerged only after 1970 with the discovery of its life cycle. In the last ten years, high resolution molecular tools have allowed the characterization of various strain types with different virulence patterns, and current studies are exploring the distribution of these different genotypes. In parallel, sophisticated diagnostic tools have been developed and awareness of disease burden has led some European countries with high prevalence rates to implement screening of pregnant women. In this article, the screening options and therapies used to prevent congenital toxoplasmosis are dissected in the light of recent data from cohort studies and other epidemiological data.
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Toxoplasma gondii prevalence in food animals and rodents in different regions of China: isolation, genotyping and mouse pathogenicity. Parasit Vectors 2013; 6:273. [PMID: 24330536 PMCID: PMC3849108 DOI: 10.1186/1756-3305-6-273] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Accepted: 09/17/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Recent studies of Toxoplasma gondii isolates from animals in different regions of China have shown a limited genetic diversity and type China 1 was the dominant genotype of T. gondii prevalent in Chinese animals. However, little has been known concerning the isolation and genotyping of T. gondii circulating in chickens, pigs and rodents in China. The aim of the study was to characterize samples of T. gondii isolates obtained from naturally infected cats, pigs and free-range chickens slaughtered for human consumption in China. METHODS In the present study, brain tissues of 77 animals collected from different areas of China, including 24 free-range chickens (Gallus domesticus) , 13 voles (Rattus flavipectus), 23 pigs and 17 cats, were bioassayed in mice and viable T. gondii were isolated from the brains of eleven. These eleven T. gondii isolates were maintained in Kunming (KM) outbred mice and DNA isolated from tissues of infected mice was characterized using 11 PCR-restriction fragment length polymorphism (PCR-RFLP) markers: SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, Apico, and CS3. Moreover, to determine mouse virulence of China 1 lineage of parasites, a TgCtgy5 genotype isolate was selected randomly and assessed in KM mice with different inoculation doses. RESULTS Results of genotyping revealed that ten isolates were type China 1 (ToxoDB PCR-RFLP genotype #9), and TgCksz1 was a new genotype that was reported for the first time designated here as ToxoDB PCR-RFLP #225. No clonal types I, II and III lineages were found. DNA sequencing of four introns (EF1, HP2, UPRT1 and UPRT7) and two genes (GRA6 and GRA7) from representative isolates confirmed the results of PCR-RFLP genotyping. The TgCtgy5 isolate was highly virulent in KM mice; all infected mice died of acute toxoplasmosis, irrespective of the inoculation dose. The results indicate that mouse virulent isolates of T. gondii are predominantly circulating in cats in China. CONCLUSIONS T. gondii isolated from chickens, pigs, cats and rodents in different locations in China were genotyped and the results reconfirmed the limited diversity of T. gondii in China and showed that type China 1 lineage was dominant in this country.
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Seroprevalence, detection of DNA in blood and milk, and genotyping of Toxoplasma gondii in a goat population in Italy. BIOMED RESEARCH INTERNATIONAL 2013; 2013:905326. [PMID: 24093106 PMCID: PMC3777175 DOI: 10.1155/2013/905326] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 08/01/2013] [Indexed: 11/20/2022]
Abstract
Toxoplasma gondii is the causative agent of a major zoonosis with cosmopolitan distribution and is known to be transmitted mainly by the ingestion of undercooked or raw animal products. Drinking unpasteurized goat's milk is a risk factor associated with human toxoplasmosis. However, very little is known about the excretion of DNA in goat milk. Aim of the present study was to determine the seroprevalence of T. gondii infection using a modified agglutination test (MAT), to detect T. gondii DNA by nested-PCR (n-PCR) in samples of blood and milk from seropositive goats, and to genotype DNA isolates using 11 molecular markers in 127 adult lactating goats from 6 farms in Italy. Positive MAT results were found in 60.6% of goats while 13% of blood and milk samples from seropositive goats were positive to n-PCR. A kappa coefficient of 1 indicated a perfect agreement between blood and milk n-PCR. Genetic characterization of isolates revealed the occurrence of genotype III (n = 7), genotype I (n = 1), and atypical genotypes with hints for genotype I (n = 2). Our results suggest that the risk of excretion of Toxoplasma tachyzoites might frequently occur in milk of seropositive goats testing positive to n-PCR on blood.
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Bangoura B, Zöller B, Koethe M, Ludewig M, Pott S, Fehlhaber K, Straubinger R, Daugschies A. Experimental Toxoplasma gondii oocyst infections in turkeys (Meleagris gallopavo). Vet Parasitol 2013; 196:272-7. [DOI: 10.1016/j.vetpar.2013.03.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 03/26/2013] [Accepted: 03/27/2013] [Indexed: 10/27/2022]
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Isolation and characterization of new genetic types of Toxoplasma gondii and prevalence of Trichinella murrelli from black bear (Ursus americanus). Vet Parasitol 2013; 196:24-30. [DOI: 10.1016/j.vetpar.2013.02.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 02/08/2013] [Accepted: 02/13/2013] [Indexed: 02/03/2023]
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Evidence of the three main clonalToxoplasma gondiilineages from wild mammalian carnivores in the UK. Parasitology 2013; 140:1768-76. [DOI: 10.1017/s0031182013001169] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
SUMMARYToxoplasma gondiiis a zoonotic pathogen defined by three main clonal lineages (types I, II, III), of which type II is most common in Europe. Very few data exist on the prevalence and genotypes ofT. gondiiin the UK. Wildlife can act as sentinel species forT. gondiigenotypes present in the environment, which may subsequently be transmitted to livestock and humans. DNA was extracted from tissue samples of wild British carnivores, including 99 ferrets, 83 red foxes, 70 polecats, 65 mink, 64 badgers and 9 stoats. Parasite DNA was detected using a nested ITS1 PCR specific forT. gondii, PCR positive samples were subsequently genotyped using five PCR–RFLP markers.Toxoplasma gondiiDNA was detected within all these mammal species and prevalence varied from 6·0 to 44·4% depending on the host. PCR–RFLP genotyping identified type II as the predominant lineage, but type III and type I alleles were also identified. No atypical or mixed genotypes were identified within these animals. This study demonstrates the presence of alleles for all three clonal lineages with potential for transmission to cats and livestock. This is the first DNA-based study ofT. gondiiprevalence and genotypes across a broad range of wild British carnivores.
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Jiang HH, Huang SY, Zhou DH, Zhang XX, Su C, Deng SZ, Zhu XQ. Genetic characterization of Toxoplasma gondii from pigs from different localities in China by PCR-RFLP. Parasit Vectors 2013; 6:227. [PMID: 23919620 PMCID: PMC3750303 DOI: 10.1186/1756-3305-6-227] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 08/01/2013] [Indexed: 11/18/2022] Open
Abstract
Background Toxoplasma gondii is a widely prevalent protozoan parasite that causes serious toxoplasmosis in humans and animals. The present study aimed to determine the genetic diversity of T. gondii isolates from pigs in Jiangxi, Sichuan, Guangdong Provinces and Chongqing Municipality in China using multilocous polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technology. Methods A total of 38 DNA samples were extracted from hilar lymph nodes of pigs with suspected toxoplasmosis, and were detected for the presence of T. gondii by semi-nested PCR of B1 gene. The positive DNA samples were typed at 11 genetic markers, including 10 nuclear loci, namely, SAG1, 5′-SAG2 and 3′-SAG2, alternative SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and an apicoplast locus Apico. Results Twenty-five of the 38 DNA samples were T. gondii B1 gene positive. Complete genotyping data for all loci could be obtained for 17 of the 25 samples. Two genotypes were revealed (ToxoDB PCR-RFLP genotypes #9 and #3). Sixteen samples belong to genotype #9 which is the major lineage in mainland China and one sample belongs to genotype #3 which is Type II variant. Conclusions To our knowledge, this is the first report of genetic typing of T. gondii isolates from pigs in Jiangxi, Sichuan Province and Chongqing Municipality, and the first report of ToxoDB #3 T. gondii from pigs in China. These results have implications for the prevention and control of foodborne toxoplasmosis in humans.
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Affiliation(s)
- Hai-Hai Jiang
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province, PR China.
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Yang N, Farrell A, Niedelman W, Melo M, Lu D, Julien L, Marth GT, Gubbels MJ, Saeij JPJ. Genetic basis for phenotypic differences between different Toxoplasma gondii type I strains. BMC Genomics 2013; 14:467. [PMID: 23837824 PMCID: PMC3710486 DOI: 10.1186/1471-2164-14-467] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 07/03/2013] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Toxoplasma gondii has a largely clonal population in North America and Europe, with types I, II and III clonal lineages accounting for the majority of strains isolated from patients. RH, a particular type I strain, is most frequently used to characterize Toxoplasma biology. However, compared to other type I strains, RH has unique characteristics such as faster growth, increased extracellular survival rate and inability to form orally infectious cysts. Thus, to identify candidate genes that could account for these parasite phenotypic differences, we determined genetic differences and differential parasite gene expression between RH and another type I strain, GT1. Moreover, as differences in host cell modulation could affect Toxoplasma replication in the host, we determined differentially modulated host processes among the type I strains through host transcriptional profiling. RESULTS Through whole genome sequencing, we identified 1,394 single nucleotide polymorphisms (SNPs) and insertions/deletions (indels) between RH and GT1. These SNPs/indels together with parasite gene expression differences between RH and GT1 were used to identify candidate genes that could account for type I phenotypic differences. A polymorphism in dense granule protein, GRA2, determined RH and GT1 differences in the evasion of the interferon gamma response. In addition, host transcriptional profiling identified that genes regulated by NF-ĸB, such as interleukin (IL)-12p40, were differentially modulated by the different type I strains. We subsequently showed that this difference in NF-ĸB activation was due to polymorphisms in GRA15. Furthermore, we observed that RH, but not other type I strains, recruited phosphorylated IĸBα (a component of the NF-ĸB complex) to the parasitophorous vacuole membrane and this recruitment of p- IĸBα was partially dependent on GRA2. CONCLUSIONS We identified candidate parasite genes that could be responsible for phenotypic variation among the type I strains through comparative genomics and transcriptomics. We also identified differentially modulated host pathways among the type I strains, and these can serve as a guideline for future studies in examining the phenotypic differences among type I strains.
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Affiliation(s)
- Ninghan Yang
- Biology Department, Massachusetts Institute of Technology, 77 Massachusetts Ave, building 68-270, Cambridge, MA 02139, USA
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Cong W, Huang SY, Zhou DH, Zhang XX, Zhang NZ, Zhao Q, Zhu XQ. Prevalence and genetic characterization of Toxoplasma gondii in house sparrows (Passer domesticus) in Lanzhou, China. THE KOREAN JOURNAL OF PARASITOLOGY 2013; 51:363-7. [PMID: 23864750 PMCID: PMC3712113 DOI: 10.3347/kjp.2013.51.3.363] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 03/16/2013] [Accepted: 03/20/2013] [Indexed: 11/25/2022]
Abstract
The prevalence of Toxoplasma gondii infection in birds has epidemiological significance because birds are indeed considered as a good indicator of environmental contamination by T. gondii oocysts. In this study, the prevalence of T. gondii in 313 house sparrows in Lanzhou, northwestern China was assayed by the modified agglutination test (MAT). Antibodies to T. gondii were positive in 39 (12.46%) of 313 samples (MAT titer ≥ 1:5). Tissues of heart, brain, and lung from the 39 seropositive house sparrows were tested for T. gondii DNA, 11 of which were found to be positive for the T. gondii B1 gene by PCR amplification. These positive DNA samples were typed at 9 genetic markers, including 8 nuclear loci, i.e., SAG1, 5'- and 3'-SAG2, alternative SAG2, SAG3, GRA6, L358, PK1, c22-8 and an apicoplast locus Apico. Of them, 4 isolates were genotyped with complete data for all loci, and 2 genotypes (Type II variants; ToxoDB #3 and a new genotype) were identified. These results showed that there is a potential risk for human infection with T. gondii in this region. To our knowledge, this is the first report of T. gondii seroprevalence in house sparrows in China.
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Affiliation(s)
- Wei Cong
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, PR China
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Döşkaya M, Caner A, Ajzenberg D, Değirmenci A, Dardé ML, Can H, Erdoğan DD, Korkmaz M, Uner A, Güngör C, Altıntaş K, Gürüz Y. Isolation of Toxoplasma gondii strains similar to Africa 1 genotype in Turkey. Parasitol Int 2013; 62:471-4. [PMID: 23811201 DOI: 10.1016/j.parint.2013.06.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 05/22/2013] [Accepted: 06/21/2013] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Toxoplasma gondii is a protozoon parasite that has a worldwide dissemination. It can cause serious clinical problems such as congenital toxoplasmosis, retinochoroiditis, and encephalitis. Currently, T. gondii genotypes are being associated with these clinical presentations which may help clinicians design their treatment strategy. CASE REPORTS Two T. gondii strains named Ankara and Ege-1 were isolated from newborns with congenital toxoplasmosis in Central and Western Anatolia, respectively. Ankara and Ege-1 strains were isolated from the cerebrospinal fluid of newborns. According to microsatellite analysis, Ankara and Ege-1 strains were sorted as Africa 1 genotype. CONCLUSION T. gondii strains isolated in Turkey were first time genotyped in this study. Africa 1 genotype has previously been isolated in immunosuppressed patients originating from sub-Saharan Africa. The reason of detecting a strain mainly detected in Africa can be associated with Turkey's specific geographical location. Turkey is like a bridge between Asia, Europe and Africa. Historically, Anatolia was on the Silk Road and other trading routes that ended in Europe. Thus, detecting Africa 1 strain in Anatolia can be anticipated. Consequently, strains detected mainly in Europe and Asia may also be detected in Anatolia and vice versa. Therefore, further studies are required to isolate more strains from Turkey.
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Affiliation(s)
- Mert Döşkaya
- Department of Parasitology, Ege University Medical School, Bornova/İzmir 35100, Turkey.
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VanWormer E, Fritz H, Shapiro K, Mazet JAK, Conrad PA. Molecules to modeling: Toxoplasma gondii oocysts at the human-animal-environment interface. Comp Immunol Microbiol Infect Dis 2013; 36:217-31. [PMID: 23218130 PMCID: PMC3779781 DOI: 10.1016/j.cimid.2012.10.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Revised: 10/17/2012] [Accepted: 10/22/2012] [Indexed: 10/27/2022]
Abstract
Environmental transmission of extremely resistant Toxoplasma gondii oocysts has resulted in infection of diverse species around the world, leading to severe disease and deaths in human and animal populations. This review explores T. gondii oocyst shedding, survival, and transmission, emphasizing the importance of linking laboratory and landscape from molecular characterization of oocysts to watershed-level models of oocyst loading and transport in terrestrial and aquatic systems. Building on discipline-specific studies, a One Health approach incorporating tools and perspectives from diverse fields and stakeholders has contributed to an advanced understanding of T. gondii and is addressing transmission at the rapidly changing human-animal-environment interface.
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Affiliation(s)
- Elizabeth VanWormer
- One Health Institute, School of Veterinary Medicine, University of California-Davis, 1 Shields Avenue, Davis, CA 95616, USA.
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177
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Dubey JP, Randall AR, Choudhary S, Ferreira LR, Verma SK, Oliveira S, Kwok OCH, Su C. Occurrence, isolation, and genetic characterization of Toxoplasma gondii from white-tailed deer (Odocoileus virginianus) in New Jersey. J Parasitol 2013; 99:763-9. [PMID: 23574007 DOI: 10.1645/13-209.1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The ingestion of uncooked infected white-tailed deer (WTD) tissues can transmit Toxoplasma gondii infection to humans and mesocarnivores, including cats. In the present study, we tested 264 WTD from New Jersey for T. gondii infection during the 2011-2012 hunting season. Serum samples were tested for antibodies to T. gondii by the modified agglutination test (cutoff titer, 25); 76 (28.7%) of 264 WTD were seropositive. Heart muscle samples from 64 seropositive WTD were digested in pepsin, and the digests were bioassayed for the isolation of T. gondii . Viable T. gondii was isolated in mice from the myocardium of 9 WTD; tachyzoites from infected mouse tissues were further propagated in cell culture. One of the 9 strains was highly virulent for outbred Swiss Webster mice. The DNA isolated from culture-derived tachyzoites of these 9 T. gondii isolates was characterized using 11 PCR-RFLP markers (SAG1, 5'- and 3'-SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico). Six genotypes were found, including ToxoDB genotype no. 2 (Type III), no. 3 (Type II variant), no. 4 (Type 12), no. 216, no. 220, and no. 221. The last 2 were new genotypes that were reported for the first time. This is the first report of T. gondii infection in deer from this region of the United States.
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Affiliation(s)
- J P Dubey
- United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Building 1001, Beltsville, Maryland 20705-2350
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Prevalence and genetic characterization of Toxoplasma gondii in bats in Myanmar. Appl Environ Microbiol 2013; 79:3526-8. [PMID: 23542631 DOI: 10.1128/aem.00410-13] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We detected Toxoplasma gondii in 29.3% (95% confidence interval [CI], 25.5% to 33.1%) of 550 insectivorous bats collected in Myanmar. The genotyping of these positive samples revealed they were closely related to or belong to clonal type I, which is highly virulent in mice, showing that these bats are potential reservoirs for T. gondii transmission.
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Schneider AG, Abi Abdallah DS, Butcher BA, Denkers EY. Toxoplasma gondii triggers phosphorylation and nuclear translocation of dendritic cell STAT1 while simultaneously blocking IFNγ-induced STAT1 transcriptional activity. PLoS One 2013; 8:e60215. [PMID: 23527309 PMCID: PMC3603897 DOI: 10.1371/journal.pone.0060215] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 02/23/2013] [Indexed: 12/29/2022] Open
Abstract
The protozoan Toxoplasma gondii actively modulates cytokine-induced JAK/STAT signaling pathways to facilitate survival within the host, including blocking IFNγ-mediated STAT1-dependent proinflammatory gene expression. We sought to further characterize inhibition of STAT1 signaling in infected murine dendritic cells (DC) because this cell type has not previously been examined, yet is known to serve as an early target of in vivo infection. Unexpectedly, we discovered that T. gondii infection alone induced sustained STAT1 phosphorylation and nuclear translocation in DC in a parasite strain-independent manner. Maintenance of STAT1 phosphorylation required active invasion but intracellular parasite replication was dispensable. The parasite rhoptry protein ROP16, recently shown to mediate STAT3 and STAT6 phosphorylation, was not required for STAT1 phosphorylation. In combination with IFNγ, T. gondii induced synergistic STAT1 phosphorylation and binding of aberrant STAT1-containing complexes to IFNγ consensus sequence oligonucleotides. Despite these findings, parasite infection blocked STAT1 binding to the native promoters of the IFNγ-inducible genes Irf-1 and Lrg47, along with subsequent gene expression. These results reinforce the importance of parasite-mediated blockade of IFNγ responses in dendritic cells, while simultaneously showing that T. gondii alone induces STAT1 phosphorylation.
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Affiliation(s)
- Anne G. Schneider
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
| | - Delbert S. Abi Abdallah
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
| | - Barbara A. Butcher
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
| | - Eric Y. Denkers
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
- * E-mail:
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Monteiro RM, Keid LB, Richtzenhain LJ, Valadas SY, Muller G, Soares RM. Extensively variable surface antigens of Sarcocystis spp. infecting Brazilian marsupials in the genus Didelphis occur in myriad allelic combinations, suggesting sexual recombination has aided their diversification. Vet Parasitol 2013; 196:64-70. [PMID: 23433642 DOI: 10.1016/j.vetpar.2013.01.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 01/23/2013] [Accepted: 01/24/2013] [Indexed: 11/26/2022]
Abstract
Sarcocystis neurona and Sarcocystis falcatula are very similar species of Apicomplexan protozoa that use marsupials of the genus Didelphis as definitive hosts. These mammals can serve as definitive hosts not only for these two parasites, but for other Sarcocystis such as Sarcocystis speeri and Sarcocystis lindsayi. Sarcocystis shed by opossums (with the exception of S. neurona) can cause disease in a great variety of birds, being commonly associated with acute pulmonary sarcocystosis in zoos. S. neurona is the most commonly associated parasite with the equine protozoal myeloencephalitis in horses. Herein we assessed the variability of Sarcocystis spp. isolated from opossums of the state of Rio Grande do Sul, Brazil, by sequencing fragments of genes coding for glycosylphosphatidylinositol-anchored surface antigens (termed surface antigen or SAG), SAG2, SAG3 and SAG4. Two genetic groups were identified, one of them related to S. falcatula and the other related to S. neurona. Various allelic combinations of SAG2, SAG3 and SAG4 occur among S. falcatula related isolates and strong evidences suggest that such isolates may exchange high divergent alleles in possible sexual recombination processes. Regarding the group S. neurona-like (isolates G37 and G38), none of the individuals in this group share alleles with individuals of the other group. Comparing G37 and G38 strains and North American strains of S. neurona, four polymorphisms were identified at SAG-3, five at SAG-2 and three at SAG-4. Gene sequences of locus SAG-3 from isolates G37 and G38 differed from the other sequences by an insertion 81bp long. This insertion contains several dinucleotide repeats of AT, resembling a microsatellite locus and has already been detected in SAG3 sequences of S. neurona from North America. When aligned against North American strains of S. neurona, G37 and G38 isolates have a deletion of 8 nucleotides within this intron which indicate that S. neurona strains of South America are divergent from that of North America. From the results obtained so far, we have shown extensive variability in surface antigens coding sequences among Sarcocystis eliminated by mammals of the genus Didelphis spp. In addition, such divergent alleles may be exchanged in possible sexual recombination processes between different isolates of S. falcatula related isolate. The evolutionary relationships within S. falcatula related isolates will be best clarified after markers less subjected to selection pressures are analyzed in conjunction with surface antigen genes. These results may have a striking impact on the knowledge of the Sarcocystis species that infect opossums in Brazil and also in the epidemiology of the infections caused by these protozoans.
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Affiliation(s)
- R M Monteiro
- Department of Preventive Veterinary Medicine and Animal Health, University of Sao Paulo, Sao Paulo, Sao Paulo, Brazil
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182
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Genetic diversity of Toxoplasma gondii isolates from Ethiopian feral cats. Vet Parasitol 2013; 196:206-8. [PMID: 23411374 DOI: 10.1016/j.vetpar.2013.01.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 01/15/2013] [Accepted: 01/17/2013] [Indexed: 11/21/2022]
Abstract
Recent studies indicate greater genetic variability among isolates of Toxoplasma gondii worldwide than previously thought. However, there is no information on genetic diversity of T. gondii from any host in Ethiopia. In the present study, genotyping was performed on viable T. gondii isolates by bioassays in mice from tissues and feces of 27 cats from Ethiopia. Viable T. gondii was isolated from hearts of 26 cats, feces alone of 1 cat, and feces and tissues of 6 cats; in total there were 33 isolates. Genotyping was performed on DNA from cell-cultured derived T. gondii tachyzoites and by using 10 PCR-restriction fragment length polymorphism markers (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico). Four genotypes were recognized, including ToxoDB #1 (Type II clonal, nine isolates), ToxoDB #2 (Type III, five isolates), Toxo DB #3 (Type II variant, ten isolates), and ToxoDB #20 (nine isolates). Of interest is the isolation of different genotypes from tissues and feces of two cats, suggesting re-infection or mixed strain T. gondii infection. These findings are of epidemiological significance with respect to shedding of oocysts by cats. This is the first report of genotyping of T. gondii from any host in Ethiopia.
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Isolation and genetic characterization of Toxoplasma gondii from mute swan (Cygnus olor) from the USA. Vet Parasitol 2013; 195:42-6. [PMID: 23394800 DOI: 10.1016/j.vetpar.2012.12.051] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 12/27/2012] [Accepted: 12/31/2012] [Indexed: 11/23/2022]
Abstract
Little is known of the genetic diversity of Toxoplasma gondii circulating in wildlife. In the present study, antibodies to T. gondii were determined in serum samples from 632 mute swans (Cygnus olor) collected from different areas of the USA. Sera were tested by T. gondii modified agglutination test; 54 (8.5%) of 632 samples were seropositive with titers of 25 in 28 sera, 50 in 22 sera, 100 in three samples, and 200 or higher in one swan. Hearts from 14 seropositive swans were bioassayed in mice and viable T. gondii (designated TgSwanUs1-3) were isolated from the hearts of three. These three T. gondii isolates were further propagated in cell culture, and DNA isolated from culture-derived tachyzoites was characterized using 11 PCR-RFLP markers (SAG1, 5'- and 3'-SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico). Results of genotyping revealed that two strains (TgSwanUs1, TgSwanUs2) were Type III (ToxoDB PCR-RFLP genotype #2), and TgSwanUs3 was a new genotype designated here as ToxoDB PCR-RFLP genotype #216. Pathogenicity of oocysts derived from these three strains was determined in Swiss Webster (SW) outbred mice. All mice infected with oocysts and tachyzoites of the atypical isolate (TgSwanUs3) died of acute toxoplasmosis, irrespective of the dose. Oocysts of the remaining two isolates were less pathogenic but differed from each other; 10 oocysts of the TgSwanUs1 killed all inoculated mice whereas 1 million oocysts of the TgSwanUs2 were needed to kill all infected SW mice. Isolation of T. gondii from mute swan indicates that the local waters were contaminated by T. gondii oocysts, and that mouse T. gondii virulent strains are circulating in wildlife. Mute swan is a new host record for T. gondii.
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184
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Wang L, Chen H, Liu D, Huo X, Gao J, Song X, Xu X, Huang K, Liu W, Wang Y, Lu F, Lun ZR, Luo Q, Wang X, Shen J. Genotypes and mouse virulence of Toxoplasma gondii isolates from animals and humans in China. PLoS One 2013; 8:e53483. [PMID: 23308233 PMCID: PMC3538538 DOI: 10.1371/journal.pone.0053483] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 11/30/2012] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Recent population structure studies of T. gondii revealed that a few major clonal lineages predominated in different geographical regions. T. gondii in South America is genetically and biologically divergent, whereas this parasite is remarkably clonal in North America and Europe with a few major lineages including Types I, II and III. Information on genotypes and mouse virulence of T. gondii isolates from China is scarce and insufficient to investigate its population structure, evolution, and transmission. METHODOLOGY/PRINCIPAL FINDINGS Genotyping of 23 T. gondii isolates from different hosts using 10 markers for PCR-restriction fragment length polymorphism analyses (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico) revealed five genotypes; among them three genotypes were atypical and two were archetypal. Fifteen strains belong to the Chinese 1 lineage, which has been previously reported as a widespread lineage from swine, cats, and humans in China. Two human isolates fall into the type I and II lineages and the remaining isolates belong to two new atypical genotypes (ToxoDB#204 and #205) which has never been reported in China. Our results show that these genotypes of T. gondii isolates are intermediately or highly virulent in mice except for the strain TgCtwh6, which maintained parasitemia in mice for 35 days post infection although it possesses the uniform genotype of Chinese 1. Additionally, phylogenetic network analyses of all isolates of genotype Chinese 1 are identical, and there is no variation based on the sequence data generated for four introns (EF1, HP2, UPRT1 and UPRT7) and two dense granule proteins (GRA6 and GRA7). CONCLUSION/SIGNIFICANCE A limited genetic diversity was found and genotype Chinese 1 (ToxoDB#9) is dominantly circulating in mainland China. The results will provide a useful profile for deep insight to the population structure, epidemiology and biological characteristics of T. gondii in China.
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Affiliation(s)
- Lin Wang
- Department of Parasitology, Provincial Laboratory of Microbiology & Parasitology and the Key Laboratory of Zoonoses Anhui, Anhui Medical University, Hefei, Anhui, China
- Clinical Laboratory, the First Affiliated Hospital of Anhui University of Traditional Chinese Medicine, Hefei, Anhui, China
| | - He Chen
- Clinical Laboratory, the First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China
| | - Daohua Liu
- Provincial Institute of Parasitic Diseases Control Anhui, Hefei, Anhui, China
| | - Xingxing Huo
- Clinical Laboratory, the First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China
| | - Jiangmei Gao
- State Key Laboratory of Biocontrol, School of Life Sciences, the Key laboratory of Tropical Diseases Control, the Ministry of Education, and the Department of Parasitology, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Xiaorong Song
- Department of Parasitology, Provincial Laboratory of Microbiology & Parasitology and the Key Laboratory of Zoonoses Anhui, Anhui Medical University, Hefei, Anhui, China
| | - Xiucai Xu
- Department of Parasitology, Provincial Laboratory of Microbiology & Parasitology and the Key Laboratory of Zoonoses Anhui, Anhui Medical University, Hefei, Anhui, China
| | - Kaiquan Huang
- Clinical Laboratory, the First Affiliated Hospital of Anhui University of Traditional Chinese Medicine, Hefei, Anhui, China
| | - Wenqi Liu
- Department of Parasitology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Yong Wang
- Department of Pathogen Biology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Fangli Lu
- Department of Parasitology, and the Key Laboratory of Tropical Disease Control, Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Zhao-Rong Lun
- State Key Laboratory of Biocontrol, School of Life Sciences, the Key laboratory of Tropical Diseases Control, the Ministry of Education, and the Department of Parasitology, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Qingli Luo
- Department of Parasitology, Provincial Laboratory of Microbiology & Parasitology and the Key Laboratory of Zoonoses Anhui, Anhui Medical University, Hefei, Anhui, China
| | - Xuelong Wang
- Department of Parasitology, Provincial Laboratory of Microbiology & Parasitology and the Key Laboratory of Zoonoses Anhui, Anhui Medical University, Hefei, Anhui, China
| | - Jilong Shen
- Department of Parasitology, Provincial Laboratory of Microbiology & Parasitology and the Key Laboratory of Zoonoses Anhui, Anhui Medical University, Hefei, Anhui, China
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185
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Webster JP, Kaushik M, Bristow GC, McConkey GA. Toxoplasma gondii infection, from predation to schizophrenia: can animal behaviour help us understand human behaviour? J Exp Biol 2013; 216:99-112. [PMID: 23225872 PMCID: PMC3515034 DOI: 10.1242/jeb.074716] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 09/08/2012] [Indexed: 12/15/2022]
Abstract
We examine the role of the protozoan Toxoplasma gondii as a manipulatory parasite and question what role study of infections in its natural intermediate rodent hosts and other secondary hosts, including humans, may elucidate in terms of the epidemiology, evolution and clinical applications of infection. In particular, we focus on the potential association between T. gondii and schizophrenia. We introduce the novel term 'T. gondii-rat manipulation-schizophrenia model' and propose how future behavioural research on this model should be performed from a biological, clinical and ethically appropriate perspective.
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Affiliation(s)
- Joanne P. Webster
- Department of Infectious Disease Epidemiology, School of Public Health, Imperial College Faculty of Medicine, London, W2 1PG, UK
| | - Maya Kaushik
- Department of Infectious Disease Epidemiology, School of Public Health, Imperial College Faculty of Medicine, London, W2 1PG, UK
| | - Greg C. Bristow
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Glenn A. McConkey
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
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186
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Genetic characterisation of Toxoplasma gondii isolates from European beavers (Castor fiber) and European wildcats (Felis silvestris silvestris). Vet Parasitol 2013; 191:108-11. [DOI: 10.1016/j.vetpar.2012.08.026] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 08/07/2012] [Accepted: 08/27/2012] [Indexed: 11/21/2022]
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187
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El Behairy AM, Choudhary S, Ferreira LR, Kwok OCH, Hilali M, Su C, Dubey JP. Genetic characterization of viable Toxoplasma gondii isolates from stray dogs from Giza, Egypt. Vet Parasitol 2012; 193:25-9. [PMID: 23333072 DOI: 10.1016/j.vetpar.2012.12.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 12/05/2012] [Accepted: 12/10/2012] [Indexed: 11/19/2022]
Abstract
Stray dogs are considered as sentinels in the epidemiology of Toxoplasma gondii because they are carnivores and eat variety of foods, including garbage. In the present study, tissues and sera of 51 stray dogs (Canis familiaris) from Giza, Egypt were examined for T. gondii infection. Sera were examined for antibodies to T. gondii by the modified agglutination test (MAT); 50 of 51 (98%) were seropositive with titers of 20 in four, 40 in four, 80 in one, 100 in eight, 200 in 17, 400 in 11, 800 or higher in five. Hearts of 43 seropositive dogs were bioassayed in mice. Viable T. gondii was isolated from 22 dogs; these isolates were designated TgDogEg1 to TgDogEg22. DNA isolated from cell culture derived tachyzoites of 22 isolates was genotyped using 10 PCR-restriction fragment length polymorphism markers (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico). The results revealed three genotypes and one mixed infection. The three genotypes are ToxoDB PCR-RFLP #2 (type III, four isolates), #3 (type II variant, 11 isolates), #20 (six isolates), 1 mixed infection. These results revealed the dominance of clonal type II, III and ToxoDB #20 lineages of T. gondii in stray dogs from Giza, Egypt.
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Affiliation(s)
- A M El Behairy
- Parasitology Department, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt
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188
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Isolation and genotyping of Toxoplasma gondii from domestic rabbits in China to reveal the prevalence of type III strains. Vet Parasitol 2012; 193:270-6. [PMID: 23261088 DOI: 10.1016/j.vetpar.2012.11.031] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 11/22/2012] [Accepted: 11/24/2012] [Indexed: 11/20/2022]
Abstract
In this study, Toxoplasma gondii antibodies in 77 free domestic rabbits from a rural area surrounding Shanghai, China were analyzed via ELISA, which identified 18 seropositive rabbits. One strain of T. gondii (designated SHR) was successfully isolated from one seropositive rabbit using a mouse bioassay. The isolated T. gondii killed all BALB/c mice inoculated with 10(4) tachyzoites, indicating its virulence in mice. Mn-PCR-RFLP analysis was used to type parasites recovered from cell cultures. Further analysis based on sequencing of a polymorphic intron revealed that the isolated strain contained a clonal type III genome, a rare finding in any host in China. This is the first reported isolation of T. gondii genotype III from rabbits in China. Our results suggested that type III strains are circulating in rabbits in China, which act as potential reservoirs of T. gondii transmission.
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189
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Chen J, Li ZY, Zhou DH, Liu GH, Zhu XQ. Genetic diversity among Toxoplasma gondii strains from different hosts and geographical regions revealed by sequence analysis of GRA5 gene. Parasit Vectors 2012. [PMID: 23206419 PMCID: PMC3533945 DOI: 10.1186/1756-3305-5-279] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Background Toxoplasma gondii is a highly prevalent protozoan parasite infecting a wide range of animals and humans. The epidemiological and biological diversity of T. gondii has resulted in a high genetic variation and unusual population structure in this parasite. This study examined sequence diversity in dense granule 5 (GRA5) gene among T. gondii isolates from different hosts and geographical regions. Methods The entire genome region of the GRA5 gene was amplified and sequenced from 14 T. gondii isolates, and phylogenetic relationship among these T. gondii isolates was reconstructed using Bayesian inference (BI) and maximum parsimony (MP) based on the GRA5 sequences. Results The complete sequence of the GRA5 gene was 1614 bp in length for strains TgCatBr5 and MAS, but 1617 bp for the other 12 strains. Sequence analysis identified 41 (0–1.7%) variable nucleotide positions among all isolates, with 18 variations of these being in the coding region. Variable positions in the coding region resulted in 11 amino acid substitutions, and a deletion of 3 bp in the strains TgCatBr5 and MAS leading to the deletion of one amino acid. Sequence variations resulted in the existence of polymorphic restriction sites for endonucleases AatII and MluI, allowing the differentiation of the three major clonal lineage types I, II and III by PCR-RFLP. Phylogenetic analyses using BI and MP supported the clear differentiation of the examined T. gondii strains into their respective genotypes. Conclusions This study demonstrated the existence of sequence variability in the GRA5 gene sequence among T. gondii isolates from different hosts and geographical regions, which allowed the differentiation of the examined T. gondii strains into their respective genotypes, suggesting that this highly polymorphic GRA5 locus may provide a new genetic marker for population genetic studies of T. gondii isolates.
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Affiliation(s)
- Jia Chen
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, China
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190
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Tibayrenc M, Ayala FJ. Reproductive clonality of pathogens: a perspective on pathogenic viruses, bacteria, fungi, and parasitic protozoa. Proc Natl Acad Sci U S A 2012; 109:E3305-13. [PMID: 22949662 PMCID: PMC3511763 DOI: 10.1073/pnas.1212452109] [Citation(s) in RCA: 146] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We propose that clonal evolution in micropathogens be defined as restrained recombination on an evolutionary scale, with genetic exchange scarce enough to not break the prevalent pattern of clonal population structure, a definition already widely used for all kinds of pathogens, although not clearly formulated by many scientists and rejected by others. The two main manifestations of clonal evolution are strong linkage disequilibrium (LD) and widespread genetic clustering ("near-clading"). We hypothesize that this pattern is not mainly due to natural selection, but originates chiefly from in-built genetic properties of pathogens, which could be ancestral and could function as alternative allelic systems to recombination genes ("clonality/sexuality machinery") to escape recombinational load. The clonal framework of species of pathogens should be ascertained before any analysis of biomedical phenotypes (phylogenetic character mapping). In our opinion, this model provides a conceptual framework for the population genetics of any micropathogen.
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Affiliation(s)
- Michel Tibayrenc
- Maladies Infectieuses et Vecteurs Ecologie, Génétique, Evolution et Contrôle, Institut de Rercherche pour le Développement 224, Centre National de la Recherche Scientifique 5290, Universités Montpellier 1 and 2, 34394 Montpellier Cedex 5, France; and
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697
| | - Francisco J. Ayala
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697
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191
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Yu L, Shen J, Su C, Sundermann CA. Genetic characterization of Toxoplasma gondii in wildlife from Alabama, USA. Parasitol Res 2012; 112:1333-6. [PMID: 23160892 DOI: 10.1007/s00436-012-3187-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 11/02/2012] [Indexed: 10/27/2022]
Abstract
The genetic diversity of Toxoplasma gondii circulating in wildlife is of interest to understand the transmission of this parasite in the environment. In the present study, we genetically characterized five T. gondii isolates from different wild animals including two isolates from a bobcat (Lynx rufus), one from a red-shouldered hawk (Buteo lineatus), one from a white-tailed deer (Odocoileus virginianus), and one from a bald eagle (Haliaeetus leucocephalus). Genotyping of these samples using 11 PCR-restriction fragment length polymorphism markers (SAG1, 5'- and 3'-SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico) revealed two types, including type I (ToxoDB#10) and type 12 (ToxoDB#5). This is the first report of genetic characterization of T. gondii strains in wildlife from Alabama and from a red-shouldered hawk.
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Affiliation(s)
- Li Yu
- Department of Microbiology and Parasitology, Anhui Provincial Laboratory of Microbiology and Parasitology; Anhui Key Laboratory of Zoonoses, Anhui Medical University, Hefei, 230022, People's Republic of China.
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192
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Behnke MS, Fentress SJ, Mashayekhi M, Li LX, Taylor GA, Sibley LD. The polymorphic pseudokinase ROP5 controls virulence in Toxoplasma gondii by regulating the active kinase ROP18. PLoS Pathog 2012; 8:e1002992. [PMID: 23144612 PMCID: PMC3493473 DOI: 10.1371/journal.ppat.1002992] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 09/10/2012] [Indexed: 11/28/2022] Open
Abstract
Secretory polymorphic serine/threonine kinases control pathogenesis of Toxoplasma gondii in the mouse. Genetic studies show that the pseudokinase ROP5 is essential for acute virulence, but do not reveal its mechanism of action. Here we demonstrate that ROP5 controls virulence by blocking IFN-γ mediated clearance in activated macrophages. ROP5 was required for the catalytic activity of the active S/T kinase ROP18, which phosphorylates host immunity related GTPases (IRGs) and protects the parasite from clearance. ROP5 directly regulated activity of ROP18 in vitro, and both proteins were necessary to avoid IRG recruitment and clearance in macrophages. Clearance of both the Δrop5 and Δrop18 mutants was reversed in macrophages lacking Irgm3, which is required for IRG function, and the virulence defect was fully restored in Irgm3−/− mice. Our findings establish that the pseudokinase ROP5 controls the activity of ROP18, thereby blocking IRG mediated clearance in macrophages. Additionally, ROP5 has other functions that are also Irgm3 and IFN-γ dependent, indicting it plays a general role in governing virulence factors that block immunity. The ability of microorganisms to cause disease in their hosts is often mediated by proteins that are secreted by the pathogen into the host cell as a means of disarming host signaling. Previous studies with the protozoan parasite Toxoplasma gondii have revealed that secretion of parasite protein kinases into the host cell mediates virulence in mouse, a natural host for transmission. Curiously, some of these virulence factors are active protein kinases, while other related pseudokinases lack enzymatic activity; hence, it was unclear how they functioned in promoting virulence. In the present work we demonstrate that ROP5, an inactive member of this protein kinase family, regulates the active protein kinase ROP18, which normally prevents clearance of the parasite in interferon-activated macrophages. Allosteric regulation of enzymes is a common theme in biology, but this is the first example of such a mechanism regulating a pathogen virulence factor. The potential advantage of such a layered process is that it might allow greater temporal or spatial control and perhaps protect the parasite from disabling strategies by the host.
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Affiliation(s)
- Michael S. Behnke
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Sarah J. Fentress
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Mona Mashayekhi
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Lucy X. Li
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Gregory A. Taylor
- Departments of Medicine, Molecular Genetics and Microbiology, and Immunology, Division of Geriatrics, and Center for the Study of Aging and Human Development, Duke University Medical Center, Durham, North Carolina, United States of America
- Geriatric Research, Education, and Clinical Center, VA Medical Center, Durham, North Carolina, United States of America
| | - L. David Sibley
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
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Pena HFJ, Vitaliano SN, Beltrame MAV, Pereira FEL, Gennari SM, Soares RM. PCR-RFLP genotyping of Toxoplasma gondii from chickens from Espírito Santo state, Southeast region, Brazil: new genotypes and a new SAG3 marker allele. Vet Parasitol 2012; 192:111-7. [PMID: 23116899 DOI: 10.1016/j.vetpar.2012.10.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 10/03/2012] [Accepted: 10/04/2012] [Indexed: 12/21/2022]
Abstract
Brazil is one of the regions with the highest prevalences of Toxoplasma gondii in humans and animals. Because free-range chickens become infected by feeding from ground contaminated with oocysts, the prevalence of T. gondii in this host has been widely used as an indicator of the strains prevalent in the environment. The genetic variability among T. gondii isolates from different healthy and sick hosts all over the world has been recently studied. Three clonal genetic lineages (Types I, II and III) were initially recognised as predominant in Western Europe and the United States. T. gondii strains are genetically diverse in South America. In Brazil, recombination plays an important role in strain diversification. The objective of this study was to genetically characterise T. gondii isolates from free-range chickens from Espírito Santo state, Southeast region, Brazil, using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). A total of 44 isolates among 47 previously described isolates (TgCkBr234-281) from free-range chickens were included in this study. Strain typing was performed using 12 PCR-RFLP markers: SAG1, SAG2, alt. SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, Apico and CS3. Eleven genotypes were identified. Ten isolates (23%) were grouped into four novel genotypes. Four isolates, distributed in four counties, corresponded to the Type BrI lineage, the genotype found most frequently in Brazil. No clonal Types I, II or III lineages were found. Two novel genotypes were represented by single isolates. Unique alleles were identified for the markers SAG1, c22-8 and CS3, and for the first time, a unique allele was found for the marker SAG3. Although a large number of T. gondii genotypes have already been identified from a variety of animal hosts in Brazil, new genotypes are continuously identified from different animal species. This study confirmed the diversity of T. gondii in Brazil and demonstrates clonal Type I, II and III lineages are rare in this country.
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Affiliation(s)
- H F J Pena
- Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, Brazil.
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194
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Edwards JF, Dubey JP. Toxoplasma gondii abortion storm in sheep on a Texas farm and isolation of mouse virulent atypical genotype T. gondii from an aborted lamb from a chronically infected ewe. Vet Parasitol 2012; 192:129-36. [PMID: 23099088 DOI: 10.1016/j.vetpar.2012.09.037] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 09/25/2012] [Accepted: 09/30/2012] [Indexed: 11/26/2022]
Abstract
Sheep are commonly infected with the protozoan parasite, Toxoplasma gondii. Infection may cause early embryonic death and resorption, fetal death and mummification, abortion, stillbirth, and neonatal death. Most sheep acquire T. gondii infection after birth. Recent studies reported that congenital ovine transmission of T. gondii may be more common than previously believed, but these findings are solely based on PCR data and require confirmation using other techniques to verify the findings. In the present study, during the lambing season of 2005 a toxoplasmosis abortion storm occurred in a flock of purebred Suffolk ewes on a farm in Texas. Only 14 healthy lambs were born, and 38 abortuses, mummies and weak or stillborn lambs were delivered. Another 15 fetuses identified by ultrasound were presumably resorbed or were aborted undetected. Antibodies to T. gondii were found in 37 (94.8%) of the 39 ewes and 30 of them had high titers (1:3200 or higher) when tested in the modified agglutination test (MAT). In the 2006 lambing season, two (both with MAT titers of ≥ 3200 in 2005) of 26 ewes delivered T. gondii infected lambs. T. gondii tissue cysts were found histologically in lesions of encephalitis in a lamb from one ewe and viable T. gondii (designated TgShUs55) was isolated from the brain and heart of a lamb from the second ewe. TheTgShUs55 had an atypical genotype using 10 PCR-RFLP markers, and was 100% lethal for Swiss Webster mice, irrespective of the dose or the stage of the parasite inoculated. In subsequent seasons, the ewes lambed normally. The results of the present study support the hypothesis that most sheep that have aborted due to T. gondii develop protection against future toxoplasmosis induced abortion, but the protection is not absolute.
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Affiliation(s)
- John F Edwards
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843-4467, USA
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195
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Pan S, Thompson RCA, Grigg ME, Sundar N, Smith A, Lymbery AJ. Western Australian marsupials are multiply infected with genetically diverse strains of Toxoplasma gondii. PLoS One 2012; 7:e45147. [PMID: 23028812 PMCID: PMC3454407 DOI: 10.1371/journal.pone.0045147] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 08/13/2012] [Indexed: 11/18/2022] Open
Abstract
Five different organs from 16 asymptomatic free-ranging marsupial macropods (Macropus rufus, M. fuliginosus, and M. robustus) from inland Western Australia were tested for infection with Toxoplasma gondii by multi-locus PCR-DNA sequencing. All macropods were infected with T. gondii, and 13 had parasite DNA in at least 2 organs. In total, 45 distinct T. gondii genotypes were detected. Fourteen of the 16 macropods were multiply infected with genetically distinct T. gondii genotypes that often partitioned between different organs. The presence of multiple T. gondii infections in macropods suggests that native mammals have the potential to promote regular cycles of sexual reproduction in the definitive felid host in this environment.
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Affiliation(s)
- Shuting Pan
- School of Veterinary and Biomedical Sciences, Murdoch University, Perth, Western Australia, Australia
| | - R. C. Andrew Thompson
- School of Veterinary and Biomedical Sciences, Murdoch University, Perth, Western Australia, Australia
| | - Michael E. Grigg
- Molecular Parasitology Unit, Laboratory of Parasitic Diseases, National Institutes of Allergy and Infectious Diseases, Bethesda, Maryland, United States of America
| | - Natarajan Sundar
- Molecular Parasitology Unit, Laboratory of Parasitic Diseases, National Institutes of Allergy and Infectious Diseases, Bethesda, Maryland, United States of America
| | - Andrew Smith
- School of Veterinary and Biomedical Sciences, Murdoch University, Perth, Western Australia, Australia
| | - Alan J. Lymbery
- Fish Health Unit, School of Veterinary and Biomedical Sciences, Murdoch University, Perth, Western Australia, Australia
- * E-mail:
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A review of the infection, genetics, and evolution of Neospora caninum: from the past to the present. INFECTION GENETICS AND EVOLUTION 2012; 13:133-50. [PMID: 22985682 DOI: 10.1016/j.meegid.2012.08.012] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 08/05/2012] [Accepted: 08/07/2012] [Indexed: 12/30/2022]
Abstract
This paper is a review of current knowledge on Neospora caninum in the context of other apicomplexan parasites and with an emphasis on: life cycle, disease, epidemiology, immunity, control and treatment, evolution, genomes, and biological databases and web resources. N. caninum is an obligate, intracellular, coccidian, protozoan parasite of the phylum Apicomplexa. Infection can cause the clinical disease neosporosis, which most notably is associated with abortion in cattle. These abortions are a major root cause of economic loss to both the dairy and beef industries worldwide. N. caninum has been detected in every country in which a study has been specifically conducted to detect this parasite in cattle. The major mode of transmission in cattle is transplacental (or vertical) transmission and several elements of the N. caninum life cycle are yet to be studied in detail. The outcome of an infection is inextricably linked to the precise timing of the infection coupled with the status of the immune system of the dam and foetus. There is no community consensus as to whether it is the dam's pro-inflammatory cytotoxic response to tachyzoites that kills the foetus or the tachyzoites themselves. From economic analysis the most cost-effective approach to control neosporosis is a vaccine. The perfect vaccine would protect against both infection and the clinical disease, and this implies a vaccine is needed that can induce a non-foetopathic cell mediated immunity response. Researchers are beginning to capitalise on the vast potential of -omics data (e.g. genomes, transcriptomes, and proteomes) to further our understanding of pathogens but especially to identify vaccine and drug targets. The recent publication of a genome for N. caninum offers vast opportunities in these areas.
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197
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Wang J, Liu X, Jia B, Lu H, Peng S, Piao X, Hou N, Cai P, Yin J, Jiang N, Chen Q. A comparative study of small RNAs in Toxoplasma gondii of distinct genotypes. Parasit Vectors 2012; 5:186. [PMID: 22943187 PMCID: PMC3453492 DOI: 10.1186/1756-3305-5-186] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Accepted: 08/31/2012] [Indexed: 11/19/2022] Open
Abstract
Background Toxoplasma gondii is an intracellular parasite with a significant impact on human health. Inside the mammalian and avian hosts, the parasite can undergo rapid development or remain inactive in the cysts. The mechanism that regulates parasite proliferation has not been fully understood. Small noncoding RNAs (sncRNA) such as microRNAs (miRNAs) are endogenous regulatory factors that can modulate cell differentiation and development. It is anticipated that hundreds of miRNAs regulate the expression of thousands of genes in a single organism. SncRNAs have been identified in T. gondii, however the profiles of sncRNAs expression and their potential regulatory function in parasites of distinct genotypes has largely been unknown. Methods The transcription profiles of miRNAs in the two genetically distinct strains, RH and ME49, of T. gondii were investigated and compared by a high-through-put RNA sequencing technique and systematic bioinformatics analysis. The expression of some of the miRNAs was confirmed by Northern blot analysis. Results 1,083,320 unique sequences were obtained. Of which, 17 conserved miRNAs related to 2 metazoan miRNA families and 339 novel miRNAs were identified. A total of 175 miRNAs showed strain-specific expression, of which 155 miRNAs were up-regulated in RH strain and 20 miRNAs were up-regulated in ME49 strain. Strain-specific expression of miRNAs in T. gondii could be due to activation of specific genes at different genomic loci or due to arm-switching of the same pre-miRNA duplex. Conclusions Evidence for the differential expression of miRNAs in the two genetically distinct strains of T. gondii has been identified and defined. MiRNAs of T. gondii are more species-specific as compared to other organisms, which can be developed as diagnostic biomarkers for toxoplasmosis. The data also provide a framework for future studies on RNAi-dependent regulatory mechanisms in the zoonotic parasite.
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Affiliation(s)
- Jielin Wang
- Key Laboratory of Zoonosis, Ministry of Education, Jilin University, Xi An Da Lu 5333, Changchun 130062, China
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Admixture and recombination among Toxoplasma gondii lineages explain global genome diversity. Proc Natl Acad Sci U S A 2012; 109:13458-63. [PMID: 22847430 DOI: 10.1073/pnas.1117047109] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Toxoplasma gondii is a highly successful protozoan parasite that infects all warm-blooded animals and causes severe disease in immunocompromised and immune-naïve humans. It has an unusual global population structure: In North America and Europe, isolated strains fall predominantly into four largely clonal lineages, but in South America there is great genetic diversity and the North American clonal lineages are rarely found. Genetic variation between Toxoplasma strains determines differences in virulence, modulation of host-signaling pathways, growth, dissemination, and disease severity in mice and likely in humans. Most studies on Toxoplasma genetic variation have focused on either a few loci in many strains or low-resolution genome analysis of three clonal lineages. We use whole-genome sequencing to identify a large number of SNPs between 10 Toxoplasma strains from Europe and North and South America. These were used to identify haplotype blocks (genomic regions) shared between strains and construct a Toxoplasma haplotype map. Additional SNP analysis of RNA-sequencing data of 26 Toxoplasma strains, representing global diversity, allowed us to construct a comprehensive genealogy for Toxoplasma gondii that incorporates sexual recombination. These data show that most current isolates are recent recombinants and cannot be easily grouped into a limited number of haplogroups. A complex picture emerges in which some genomic regions have not been recently exchanged between any strains, and others recently spread from one strain to many others.
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Furtado JM, Winthrop KL, Butler NJ, Smith JR. Ocular toxoplasmosis I: parasitology, epidemiology and public health. Clin Exp Ophthalmol 2012; 41:82-94. [DOI: 10.1111/j.1442-9071.2012.02821.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
| | | | - Nicholas J Butler
- Division of Ocular Immunology, Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Justine R Smith
- Casey Eye Institute
- Cell & Developmental Biology, Oregon Health & Science University, Portland, Oregon
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The rhoptry proteins ROP18 and ROP5 mediate Toxoplasma gondii evasion of the murine, but not the human, interferon-gamma response. PLoS Pathog 2012; 8:e1002784. [PMID: 22761577 PMCID: PMC3386190 DOI: 10.1371/journal.ppat.1002784] [Citation(s) in RCA: 162] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 05/16/2012] [Indexed: 12/02/2022] Open
Abstract
The obligate intracellular parasite Toxoplasma gondii secretes effector proteins into the host cell that manipulate the immune response allowing it to establish a chronic infection. Crosses between the types I, II and III strains, which are prevalent in North America and Europe, have identified several secreted effectors that determine strain differences in mouse virulence. The polymorphic rhoptry protein kinase ROP18 was recently shown to determine the difference in virulence between type I and III strains by phosphorylating and inactivating the interferon-γ (IFNγ)-induced immunity-related GTPases (IRGs) that promote killing by disrupting the parasitophorous vacuole membrane (PVM) in murine cells. The polymorphic pseudokinase ROP5 determines strain differences in virulence through an unknown mechanism. Here we report that ROP18 can only inhibit accumulation of the IRGs on the PVM of strains that also express virulent ROP5 alleles. In contrast, specific ROP5 alleles can reduce IRG coating even in the absence of ROP18 expression and can directly interact with one or more IRGs. We further show that the allelic combination of ROP18 and ROP5 also determines IRG evasion and virulence of strains belonging to other lineages besides types I, II and III. However, neither ROP18 nor ROP5 markedly affect survival in IFNγ-activated human cells, which lack the multitude of IRGs present in murine cells. These findings suggest that ROP18 and ROP5 have specifically evolved to block the IRGs and are unlikely to have effects in species that do not have the IRG system, such as humans. Toxoplasma gondii can infect any warm-blooded animal and is transmitted orally by consumption of tissue cysts. To facilitate transmission, the parasite must balance induction and evasion of host immune responses to allow parasite growth and persistence, while avoiding excessive parasite burden, which can kill the host before infectious cysts are formed. Different strains of Toxoplasma have likely evolved specific effector molecules to modulate the immune responses of different hosts. In many mammals, including mice but not humans, the cytokine interferon gamma (IFNγ) induces the immunity-related GTPases (IRGs), which are essential to the murine immune response to Toxoplasma. They function by binding to and disrupting the parasite-containing vacuole. However, some Toxoplasma strains prevent the IRGs from disrupting the parasitophorous vacuole. It was previously shown that the secreted Toxoplasma kinase ROP18 promotes virulence in mice by phosphorylating the IRGs, leading to their inactivation. We report that ROP18 requires another virulence factor, the secreted pseudokinase ROP5, to prevent IRG accumulation, and these two proteins determine the majority of strain differences in IRG evasion, even for divergent strains for which virulence determinants have not been studied. Additionally, we show that ROP18 and ROP5 do not affect Toxoplasma survival in IFNγ-stimulated human cells. Thus, ROP18 and ROP5 are strain- and host-specific determinants of Toxoplasma immune evasion.
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