Molecular epidemiology of HIV-1 subtypes in southern China

The driving forces of the HIV-1 epidemic in Guangxi, China were assessed by investigating virologic and epidemiologic data from a cohort of longitudinally followed injection drug users (IDUs) in Binyang and Pingxiang, major urban areas along 2 separate drug routes in the province. Sera and interview data were obtained in September and October of 2000. Sequence analysis of HIV-1 was per-formed on the gag-pol region (HXB2 nt 1850-3005) and C2 to V4 env (HXB2 nt 6704-7626). Sequence data demonstrated that 88% of the infections in Pingxiang were CRF01_AE, whereas 96% in Binyang were CRF08_BC. Three recently infected subjects in Pingxiang were infected with CRFOS_BC, and 1 chronically infected subject had evidence of a recombinant virus. Intersubject distances were statistically greater for CRF01_AE-infected subjects than CRF08_BC-infected subjects for all regions except V4. The epidemic in Binyang is similar to previously described IDU-based epidemics, with a strong founder effect with little variation in V3. The epidemic in Pingxiang may have had multiple introductions of the CRF01_AE epidemic into the city and greater spread through sexual transmission, resulting in greater variation in V3 than typically seen in purely parenterally based epidemics.