Two subtypes of HIV-1 among injection-drug users in southern China

The rate of HIV-1 infection has increased steadily in China by about 80% annually and by the end of September 1997, 8277 HIV-1 cases had been reported, of whom more than 75% were IV drug users (IVDUs). UNAIDS, however, has estimated that up to 200,000 people could actually be infected with HIV-1 in China. Guangxi Province borders Yunnan province in the west and Vietnam to the south, and is a major transit area for heroin trafficking from the opium-growing region of Laos and Myanmar. Phylogenetic analyses of HIV-1 env sequences (C2-V3) obtained from 14 IVDUs found that 9 subjects from Pingxiang City were infected with subtype E and 5 from Baise City with subtype C. The 9 subtype E and 5 subtype C HIV-1 sequences were clustered together within each group, with significant bootstrap values of 100% and 95%, respectively. The subtype E sequences were more closely related to HIV-1 subtype E from Thailand than to those from Africa, and the subtype C sequences were clustered more closely to those from India than to those from Africa. Study results suggest 2 epidemiologically unrelated epidemics and 2 different sources; subtype C probably transmitted from Yunnan to Baise City through drug trafficking and IVDU interaction, and subtype E coming into China from Vietnam.