[Distribution of HIV-1 subtypes among different populations in Dehong prefecture, Yunnan province, in 2011]

To investigate the distribution of HIV-1 subtypes in Dehong prefecture, Yunnan province, in 2011.

300 HIV-1 positive plasma samples were collected from Jan. 2011 to May 2011 in Dehong prefecture. HIV-1 gag genes and env genes were amplified by nested-polymerase chain reaction (PCR) from viral RNA. After sequencing, the HIV-1 subtypes were determined by phylogenetic analysis.

Based on the phylogenetic trees of gag gene and env gene fragments, a total of 222 samples were genotyped. Subtype C was the predominant strain in Dehong (43.2%, 96/222), followed by unique recombinant forms (URFs, 27.0%, 60/222), CRF01_AE (21.2%, 47/222), CRF08_BC (5.0%, 11/222), B' (2.3%, 5/222) and CRF07_BC (1.4%, 3/222). Subtype C strains were predominant in both heterosexually transmitted population and intravenous drug users (IDUs), but different subtype distribution patterns were found in these two populations. All 6 genotypes including subtype C (40.7%, 70/172), CRF01_AE (25.0%, 43/172), and URFs (25.0%, 43/172) found in this area among heterosexually transmitted population, which showed the diversity of genotypes in this population. Except subtype B' and CRF07_BC, the other 3 subtypes and URFs were detected among IDUs, mainly including subtype C (54.8%, 23/42) and URFs (38.1%, 16/42), which showed the concentration trend of genotypes distribution among IDUs. The proportion of URFs increased significantly in this area, including the new BC recombinants (41.7%, 25/60) and CRF01_AE relative URFs (58.3%, 35/60). However, the distributions of these two URFs among heterosexually transmitted population and IDUs showed no statistical significance.

The distribution of HIV-1 strains prevailing in Dehong prefecture was diversity, including 5 subtypes and a variety of URFs, of which subtype C was the predominant strain. The distribution patterns of subtype were different among different populations.