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Molecular characterization of Sarcocystis spp. isolates from marsupials of the genus Didelphis spp. through the analysis of mitochondrial and apicoplast genes, internal transcribed spacer region (ITS-1) and surface antigen genes (SAGs)

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Samantha Yuri Oshiro Branco Valadas
Total Authors: 1
Document type: Doctoral Thesis
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
Defense date:
Examining board members:
Rodrigo Martins Soares; Paulo Eduardo Brandão; Fabio Gregori; Alda Maria Backx Noronha Madeira; Sandra Mayumi Nishi
Advisor: Rodrigo Martins Soares

A great variability in surface antigens genes (SAGs) of Sarcocystis spp. sporocysts was found in a previous study, through the intestinal scraping technique of opossums from the south region of Brazil. The results indicated probable sexual recombination between lineages of Sarcocystis isolates (genetically related to Sarcocystis falcatula). The aim of this research is the study of genetic variability and phylogenetic relationships among Sarcocystis spp. isolates from captured opossums in Brazil, by the analysis of molecular markers less subjected to selective pressure, such as DNA barcode, for this purpose, genetic loci from mitochondrial (CytB) and apicoplast genome (ClpC), and internal transcribed spacer regions (ITS-1) were applied and compare the results with the diversity found within members of the Toxoplasmatinae sub-family. The diversity among the SAG-2, SAG-3 and SAG-4 genes was also studied. The Sarcocystis sporocysts were obtained from opposum’s intestinal scraping and faeces from São Paulo State, Rio Grande do Sul State and Rio Grande do Norte State, Brazil. The molecular markers CytB, ClpC and ITS-1 revealed a vast genotypic variability and novel alleles among the Brazilian isolates. The results indicate possible existence of hybrid species of Sarcocystis in Brazil, with a gene mixture from both species. Regarding the SAG genes, an even greater variability was found than previously reported. The results also suggest the occurrence of reassortment and allele recombination of SAG sequences, contributing even more to the variability and thus in the parasites antigenic configuration. In this study, the results demonstrate that isolates from Brazil have a different genetic composition than reported in other locations, which may have important impacts in the knowledge of the diversity of Sarcocystis species shed by opossums in our environment and in all of the epidemiology of infections of protozoa of this particular group (AU)

FAPESP's process: 11/10550-2 - Molecular characterization of Sarcocystis spp. isolates from marsupials of the genus Didelphis spp. through the analysis of mitocondrial and apicoplast genes, Internal Transcribed Spacers (ITS-1) and surface antigen genes
Grantee:Samantha Yuri Oshiro Branco Valadas
Support Opportunities: Scholarships in Brazil - Doctorate (Direct)