BackgroundChina is experiencing a dynamic HIV/AIDS epidemic. While serology based surveillance systems have reported the spread of HIV/AIDS, detailed tracking of its transmission in populations and regions is not possible without mapping it at the molecular level. We therefore conducted a nationwide molecular epidemiology survey across the country.MethodsHIV-1 genotypes were determined from 1,408 HIV-positive persons newly diagnosed in 2006. The prevalence of each genotype was estimated by weighting the genotype’s prevalence from each province- and risk-specific subpopulation with the number of reported cases in the corresponding subgroups in that year.ResultsCRF07_BC (35.5%), CRF01_AE (27.6%), CRF08_BC (20.1%), and subtype B' (9.6%) were the four main HIV-1 strains in China. CRF07_BC and CRF08_BC were the primary drivers of infection among injecting drug users in northeastern and southeastern China, respectively, and subtype B' remained dominant among former plasma donors in central China. In contrast, all four strains occurred in significant proportions among heterosexuals nationwide, pointing to an expansion of the HIV-1 epidemic from high-risk populations into the general population. CRF01_AE also replaced subtype B as the principal driver of infection among men-who-have-sex-with-men.ConclusionsOur study provides the first comprehensive baseline data on the diversity and characteristics of HIV/AIDS epidemic in China, reflecting unique region- and risk group-specific transmission dynamics. The results provide information critical for designing effective prevention measures against HIV transmission.

Objectives:We sought to comprehensively analyze the origin, transmission patterns and sub-epidemic clusters of the HIV-1 CRF01_AE strains in China.Methods:Available HIV-1 CRF01_AE samples indentified in national molecular epidemiologic surveys were used to generate near full-length genome (NFLG) sequences. The new and globally available CRF01_AE NFLG sequences were subjected to phylogenetic and Bayesian molecular clock analyses, and combined with epidemiologic data to elucidate the history of CRF01_AE transmission in China.Results:We generated 75 new CRF01_AE NFLG sequences from various risk populations covering all major CRF01_AE epidemic regions in China. Seven distinct phylogenetic clusters of CRF01_AE were identified. Clusters 1, 2 and 3 were prevalent among heterosexuals and IDUs in southern and southwestern provinces. Clusters 4 and 5 were found primarily among MSM in major northern cities. Clusters 6 and 7 were only detected among heterosexuals in two southeast and southwest provinces. Molecular clock analysis indicated that all CRF01_AE clusters were introduced from Southeast Asia in the 1990s, coinciding with the peak of Thailand's HIV epidemic and the initiation of China's free overseas travel policy for their citizens, which started with Thailand as the first destination country.Conclusion:China's HIV-1 epidemic of sexual transmissions, was initiated by multilineages of CRF01_AE strains, in contrast to the mono-lineage epidemic of B′ strain in former plasma donors and IDUs. Our study underscores the difficulty in controlling HIV-1 sexual transmission compared with parenteral transmission.

Background Transmission of HIV drug resistance (TDR) gives rise to reduced efficacy of initial antiretroviral treatment, and has become a public health concern. Methods A nationwide survey on TDR was conducted in antiretroviral therapy naïve HIV-1 infected individuals from September 2004 to October 2005 in China. Drug resistance genotyping was performed on subjects’ plasma samples. Drug resistance mutations were determined and scored by Stanford HIV Drug Resistance algorithm. Results Sequences were obtained from 676 individuals, of which 61.2% were former plasma and blood donors, 17.3% were infected sexually, and 17.2% were intravenous drug users. Subtype B’ HIV-1 strains were found in 73.5%, CRF01_AE in 13.9%, CRF07_BC in 6.2%, CRF08_BC in 2.7%, subtype C in 1.04%, subtype B in 0.9%, CRF02_AG in 0.4% and B’/C intersubtype recombinant strains in 1.3% of the subjects. Twenty-six (3.8%) were found to harbor drug resistance strains. The rates of resistance to PIs, NRTIs and NNRTIs were 0.4%, 1.6% and 2.1%, respectively. Though there was no significant difference in TDR rates between 2004 and 2005 (2.9% vs. 4.4%), an increased trend was observed in the rate of high-level drug resistance (0.8% in 2004 vs. 3.0% in 2005, P = 0.0634). Conclusions The rate of TDR was relatively low in China, as compared with those in developed countries. Surveys among recently HIV-infected subjects should be preformed continually to ensure the success of the scale-up antiretroviral treatment.

High prevalence of syphilis and overlapped unprotected commercial sex and drug using behaviors among FSWs along a drug-trafficking route may suggest a potential for rapid spread of HIV from injection drug users to FSWs and then to the general population and underscore the urgency of preventive interventions to break the bridge of FSWs for HIV/sexually transmitted disease spread.