Genotyping of strains from Brazilian AIDS patients with cerebral toxoplasmosis by multilocus PCR-RFLP markers

Exp Parasitol. 2007 Aug 19; [Epub ahead of print]

Toxoplasma gondii: Genotyping of strains from Brazilian AIDS patients with cerebral toxoplasmosis by multilocus PCR-RFLP markers

Ferreira IM, Vidal JE, Costa-Silva TA, Meira CS, Hiramoto RM, Penalva de Oliveira AC, Pereira-Chioccola VL

Department of Parasitology, Instituto Adolfo Lutz, Av. Dr Arnaldo, 351, 8 andar, CEP 01246-902, São Paulo, SP, Brazil.

This study investigated the genetic characteristics of the Toxoplasma gondii strains isolated from 87 patients with cerebral toxoplasmosis and AIDS, treated in Sao Paulo State, Brazil. The laboratorial diagnosis of cerebral toxoplasmosis was based on positive serological exams and PCR of blood and/or cerebrospinal fluid. Four markers (5'-SAG2, 3'-SAG2, SAG3 and GRA6) were chosen to analyze the samples. Each having clear resolution to distinguish the three clonal lineages after PCR-amplified targets were treated with restriction enzyme digestion (PCR-RFLP). The genotyping provided the following results: 40 patients (46%) were infected with strains classified as type I; 4 (4%), as type III; 13 (15%) were infected with recombinant strains (unusual genotype having types I, II and III alleles) 6 patients with type I or II alleles; and 15 (17%) patients had strains not classified for any marker. PCR-RFLP, also classified 9 (11%) clinical isolates as type II, which is uncommon in South America. However, the sequencing of the nested-PCR products (of SAG3 marker) of type II and recombinant isolates (of 5'-SAG2, SAG3 and GRA6 markers) showed a nucleotide polymorphism compared with the archetypal clonal genotypes (types I, II and III) and these isolates were considered as recombinant strains. These data confirm other studies showing the high rate of genetic exchange in T. gondii strains isolated in Brazil.

PMID: 17950282 [PubMed - as supplied by publisher]