Genetic clusters of HIV infection in men who have sex with men from a time-location sampling survey in Shenzhen, China
J. Zhao1,2, W.-D. Cai1, C.-L. Zheng1, L. Chen1, J.-Q. Cheng3, Y.-X. Gan1, X. Wang2, M.-L. He2
1Shenzhen Center for Disease Control and Prevention, Dept. of HIV/AIDS Prevention and Control, Shenzhen, China, 2The Chinese University of Hong Kong, School of Public Health and Primary Care, Hong Kong, Hong Kong, 3Shenzhen Center for Disease Control and Prevention, Shenzhen, China
Background: Men who have sex with men (MSM) become a major concern for HIV prevention and control in China in recent year, while the transmission of HIV among this population is not clearly demonstrated. This study aims to examine genetic diversity among MSM based on a time-location sampling to improve the representativeness, and to identify the characteristics of the HIV strains circulating within different subgroups of MSM.
Methods: From 2008 to 2009, a total of 1668 MSMs including 953 male sex workers were recruited from 105 different venue-date-times randomly selected out of a total of 78 venues in Shenzhen, China, using time-location sampling. Blood samples were also collected and tested for HIV. Pol region of HIV positive samples were sequenced for drug resistance and phylogenetic analysis.
Results: Among the 1668 subjects, the prevalence of HIV infection was 5.6%, with 4.6% in MSWs and 6.8% in other MSMs. CRF01_AE was the predominant subtype (51.1%) followed by CRF07_BC(36.0%) and Subtype B(10.5%). In addition, the pol gene sequences from this study were aligned together with the previous obtained HIV cases in Shenzhen. Four HIV-1 genetic clusters were observed among CRF01_AE and one big cluster including 27 study subjects and 21 more MSM samples was found among CRF07_BC. The routes of transmission of all these clusters were mainly from homosexual contact. The distribution of HIV strains in clusters showed significant difference between MSWs and other MSMs, and also a slight relation to venue types. No drug resistance was found among the HIV positive cases.
Conclusions: The variety of the HIV strains that circulated among Shenzhen MSM indicated the HIV strains were not restricted within certain transmission groups in China. A new cluster of CRF07_BC was emerged and spread rapidly among MSMs in Shenzhen and required immediate population targeting intervention.