Identification of 3 Distinct HIV-1 Founding Strains Responsible for Expanding Epidemic Among Men Who Have Sex With Men in 9 Chinese Cities

Objectives:To investigate the epidemiological relationships between HIV-1 strains that are spread among the men who have sex with men (MSM) populations of 9 cities across China and to analyze the origins and divergence times of the major epidemic strains found in the MSM population. Methods: A total of 583 HIV-1-positive subjects were recruited from high-risk MSM populations in 9 cities across China between 2009 and 2011. Nucleotide sequences of 1.0-kb pro-RT regions were amplified and sequenced. Phylogenetic and Bayesian molecular clock analyses were performed. Results: The overall distribution of HIV-1 genotypes was as follows: CRF01_AE, 62.1%; CRF07_BC, 18.2%; subtype B (United States-European), 15.9%; subtype B', 0.7%; other recombinants, 3.1%. In addition to the 2 distinct CRF01_AE clusters [cluster 1 (n = 157, 26.9%) and cluster 2 (n = 196, 33.6%)] previously reported by our group, we identified a novel CRF07_BC cluster (cluster 3) (n = 94, 16.1%) unique to China's MSM population whose strains were homologous and could be detected in all 9 cities. These 3 lineages of HIV-1 strains (clusters 1-3) accounted for 76.7% (447 of 583) of infections among MSM in China as a whole. Clusters 1, 2, and 3 were estimated to have been introduced into the MSM population in 1999, 2001, and 2001, respectively, indicating that the newly identified CRF07_BC cluster 3 is not a young lineage. However, it spread quickly in recent years. Conclusions: We identified 3 distinct HIV-1 lineages (clusters 1-3) responsible for the recent upsurge of the AIDS epidemic among MSM in China. These 3 HIV-1 variants are spread widely among MSM throughout China, demonstrating remarkable founding effects.