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Title: Population structure and virulence of Toxoplasma gondii in Brazil

item PENA, H F J
item Dubey, Jitender
item SU, C

Submitted to: International Journal for Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2007
Publication Date: 2/1/2008
Citation: Pena, H., Gennari, S.M., Dubey, J.P., Su, C. 2008. Population structure and virulence of Toxoplasma gondii in Brazil. International Journal for Parasitology. 38:561-569.

Interpretive Summary: Toxoplasma gondii is a single-celled parasite of all warm-blooded hosts worldwide. It causes mental retardation and loss of vision in children, and abortion in livestock. Cats are the main reservoir of T. gondii because they are the only hosts that can excrete the resistant stage (oocyst) of the parasite in the feces. Humans become infected by eating undercooked meat from infected animals and food and water contaminated with oocysts. Toxoplasmosis causes mortality in many species of animals in the zoos, especially primates. Scientists at the Beltsville Agricultural Research Center and University of Sao Paulo, Brazil and University of Tennessee reprt on genetic of Toxoplasma in Brazil . The results will be of interest to biologists, parasitologists, and veterinarians

Technical Abstract: Recent studies found that the isolates of T. gondii from Brazil are biologically and genetically different from those in North America and Europe. However, so far only a small number of isolates were analyzed from different animal hosts in Brazil. In the present study DNA samples of 46 T. gondii isolates from cats of 11 counties in São Paulo state, Brazil were genetically characterized using 10 PCR-RFLP markers including SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico. An additional marker CS3 which locates on chromosome VIIa and was previously shown linked to acute virulence of T. gondii was also used to determine its association to virulence in mice. Genotyping of these 46 isolates revealed a high genetic diversity with 20 genotypes but no clonal Type I, II or III lineage weas found. Two of the 46 isolates showed mixed infections. Combining genotyping data in this study with recent reported results from chickens, dogs and cats in Brazil (total 125 isolates) identified 48 genotypes and 26 of these genotypes have single isolates each, indicating that T. gondii population in Brazil is highly diverse. Four of the 48 genotypes with multiple isolates identified from different hosts and locations are considered the common lineages in Brazil. These lineages are designated as Type BrI, BrII, BrIII and BrIV. Analysis of mortality rate in infected mice indicated that Type BrI is highly virulent, Type BrIII is non-virulent, while isolates of Type BrII and BrIV lineages are variable, suggesting the intermediate or non-virulent phenotype. Taken together, T. gondii has an epidemic population structure in Brazil and the major lineages have different biological traits.