[Preliminary Analysis of the Genetic Loci of SAG1 and SAG3, the Surface Antigens of Toxoplasma gondii, in HIV-positive People in Dali of Yunnan Province].

To identify the genotypes of Toxoplasma gondii that infects HIV-positive people in Dali of Yunnan Province through analyzing the genetic loci of the surface antigens SAG1 and SAG3.A total of 291 blood samples from HIV-positive cases were collected from the HIV/AIDS Prevention and Control Institution in Yunnan. Nested PCR was used to amplify SAGI and SAG3 genes in the blood samples. The products were digested with restriction enzymes Sau96 I, Hae II and Nci I, and sequenced.Of the 291 HIV-positive blood samples, 64 showed successful amplification of SAGI gene, and 42 of SAG3 gene, with product sizes of 390 bp and 225 bp, respectively. Enzymetic digestion of the PCR products resulted in fragments of 350 bp and 50 bp for SAGI, and -200 bp band for SAG3, consistent with RH, a particular type I strain of T. gondii. Sequencing of the SAG1 and SAG3 PCR products showed that their sequence identities with SAGI (Accession No. GQ253073) and SAG3 (Accession No. JX218225.1) of the type I strain of T. gondii were 99.98%-100% and 99.96% -99.98% respectively.The Toxoplasma gondii in HIV-positive cases in Dali of Yunnan Province is the type I strain of T. gondii.