Large transmission clusters of HIV-1 main genotypes among HIV-1 individuals before antiretroviral therapy in the Hebei province, China.

In recent ten years, the sexual contact transmission has led to the consecutive upsurge of HIV in Hebei. Especially, the risk behaviors of homosexual contact in Hebei has presented challenges for HIV prevention and treatment efforts. In this study, we found that 98.9% of subjects attributed their HIV-1 infections to sexual contact, and MSM accounted for 77.5%. CRF01_AE (49.6%), CRF07_BC (29.7%) and subtype B (13.0%) was three main genotypes. AE_cluster 1 (73 cases), AE_cluster 2 (62 cases) and one large 07_BC cluster (75 cases) were identified, and only closely clustered with MSM sequences from Beijing. Further, all of HIV-1 resistant strains were circulating in transmission clusters. Particularly, 76.5% of subjects resistant to drugs were circulating in above three large transmission clusters associated with MSM from Beijing. Our study proved that the busy movement of MSM between Beijing and Hebei could meet conveniently, which might result in the bidirectional exchange of HIV-1 strains between Beijing and Hebei. As the most frequent genotypes, large transmission clusters associated with CRF01_AE and CRF07_BC have become one of main factors resulting in the rapid increase of HIV in Hebei. Therefore, the enhanced surveillance for HIV should be planned early among the floating population travelling between Beijing and Hebei. Hebei should construct the cooperative mechanism for HIV prevention and control together with Beijing.