[HIV-1 subtype and the distribution in Yunnan province]

Abstract

Objective: To understanding the genetic subtype and its population and regional distribution of HIV-1 strains circulating in Yunnan province.

Methods: 788 plasma specimens collected in 2008-2009 from 15 distracts of Yunnan, were enrolled. Viral RNA were extracted and subjected to RT-PCR. 1584 bp full length gag gene, 3147 bp full length pol gene and 558 bp env (C2V3) fragment were amplified and directly sequenced. Full length gag and pol genes were connected together as a complete genetic region (location on HXB2: 790 - 5096) for genotyping.

Results: Of the 788 plasma specimens, a total number of 1728 genomic sequences including 599 gag, 564 pol and 525 env (C2V3) were successfully amplified and sequenced, with genotype of 617 samples identified. The subtypes of HIV-1 strains circulated in Yunnan were with the order of constituent ratio CRF08_BC (50.2%), CRF01_AE (25.0%), unknown recombinant forms (10.2%), CRF07_BC (9.2%), subtype C (2.9%) and subtype B (B') (2.4%). The distributions of subtypes showed significant regional differences and could be roughly divided into two forms:the CRF08_BC predominant areas represented by Lincang and Kunming, and the areas with CRF08_BC together with CRF01_AE coexistence, represented by Dehong and Xishuangbanna. The unknown recombinant forms accounted for more HIV infection in ethnic minorities (17.0%) than in ethnic Han (6.7%, P < 0.01). The distribution of subtypes varied significantly in the two primary routes of transmission for those infected through heterosexual contact. CRF08_BC and CRF01_AE were the dominant subtypes, accounting for 52.7% and 29.1% respectively. However, in IDUs, CRF08_BC strains accounted for half of the infection, while only 4.5% of the infections were caused by CRF01_AE, CRF07_BC while the unique recombinant forms were responsible for 15.5% infections. Of the 63 unknown recombinant forms, most (74.6%) were B (B') recombinant with C, while 25% were mosaic B and/or C fragments on the bases of CRF01_AE genome.

Conclusion: The subtypes of HIV-1 strains circulated in Yunnan were complicated under the significant differences of regions, ethnics or routes of transmission.