Two subtypes of HIV-1 among injection-drug users in southern China
Authors: Xiao-Fang Yu, Jie Chen, Yiming Shao, Chris Beyrer, Shenghan Lai
Journal: The Lancet (1998)

The rate of HIV-1 infection has increased steadily in China about 80% per year.1Ministry of Health, P R China and UN Theme Group on HIV/AIDS in China. China responds to AIDS: HIV/AIDS situation and needs assessment report. 1997.Google Scholar By the end of September 1997, 8277 HIV-1-cases had been reported; more than three-quarters were injection-drug users (IDU).1Ministry of Health, P R China and UN Theme Group on HIV/AIDS in China. China responds to AIDS: HIV/AIDS situation and needs assessment report. 1997.Google Scholar UNAIDS has estimated that the actual number of HIV-1-infected people in China could be as high as 200 000.1Ministry of Health, P R China and UN Theme Group on HIV/AIDS in China. China responds to AIDS: HIV/AIDS situation and needs assessment report. 1997.Google Scholar Until 1994, Yunnan Province, with less than 5% of China's population, had more than 80% of the HIV-1 infections reported.1Ministry of Health, P R China and UN Theme Group on HIV/AIDS in China. China responds to AIDS: HIV/AIDS situation and needs assessment report. 1997.Google Scholar However, in 1995–97, drug users outside Yunnan amounted for more than 50% of new HIV-1 infections.1Ministry of Health, P R China and UN Theme Group on HIV/AIDS in China. China responds to AIDS: HIV/AIDS situation and needs assessment report. 1997.Google Scholar Guangxi Province, which borders Yunnan in the west and Vietnam in the south, is a major transit area for heroin trafficking from the opium-growing region of Laos and Myanmar. Heroin traffic may enter Guangxi either through Yunnan, or though Vietnam en route to Hong Kong and eventually to the West. In 1996–97, 91 of 227 heroin users in Pingxiang City (which borders Vietnam), and Baise City (which borders Yunnan) were found to be HIV-1 positive. Because HIV-1 infections were detected among injection-drug users from two different border cities it was of interest to determine their subtypes. Phylogenetic analysis of HIV-1 env sequences (C2-V3) obtained from 14 injection-drug users showed that nine drug users from Pingxiang (96CNGX-1 to 96CNGX-5, and 97CNGX-1 to 97CNGX-4) were infected with subtype E and the five from Baise (97CNGX-5 to 97CNGX-9) with subtype C HIV-1. The nine subtype E and five subtype C HIV-1 sequences from Guangxi were clustered together within each group, with significant bootstrap values, of 100% and 95%, respectively. The Guangxi subtype E HIV-1 sequences were more closely related to subtype E HIV-1 sequences from Thailand than to those from Africa, and the Guangxi subtype C HIV-1 sequences were clustered more closely to those from India than from Africa. For the Guangxi IDIs, the subtype E and C strains within each group were notably homogenous, as indicated by the short branch lengths in the phylogenetic tree. The mean genetic distance for all pairwise comparisons was 1·81% among the nine subtype E, and 0·98% among the five subtype C HIV-1 strains. Phylogenetic tree is available from the corresponding author. These results suggest two epidemiologically unrelated epidemics and two different sources. Subtype C was probably transmitted from Yunnan to Guangxi (Baise City) by drug trafficking and interaction between injection-drug users from Yunnan and Guangxi. This HIV-1 subtype has also been detected among drug users in Yunnan.2Lou C-C Tian C Hu DJ et al.HIV-1 subtype C in China.Lancet. 1995; 345: 1051-1052Google Scholar Although subtype E HIV-1 has been detected in Yunnan, virtually all of the reported cases involved women returning to Yunnan after sex work in Thailand.3Cheng H Zhang J Capizzi J Young NL Mastro TD HIV-1 subtype E in Yunnan, China.Lancet. 1994; 344: 953-954Abstract PubMed Scopus (88) Google Scholar Recent reports suggest that the virus circulating in vietnam, both in instances of sexual transmission and in IDUs, is predominantly subtype E.4Menu E Troung TXL LaFon M-E et al.HIV type 1 Thai subtype E is predominant in south Vietnam.AIDS Res Hum Retroviruses. 1996; 12: 629-633Crossref PubMed Scopus (54) Google Scholar, 5Nerukar VR Nguyen HT Dashwood W-M et al.HIV type 1 subtype E in commercial sex workers in IDU in southern Vietnam.AIDS Res Hum Retroviruses. 1996; 12: 841-843Crossref PubMed Scopus (40) Google Scholar Given the proximity of Pingxiang City to northern Vietnam, it is probable that the subtype E HIV-1 detected among IDUs in southern Guangxi has been transmitted across the Vietnam-China border. We collaborated with Zhe Wang, Department of Molecular Microbiology and Immunology; Wei Liu, Jinye Yang, Shaoling Liang, Guangxi Health, and Anti-Epidemic Center; Yiming Shao, Lin Su, Chinese Academy of Preventive Medicine; and Shenghan Lai.