Genomic characterization of two novel HIV-1 unique (CRF01_AE/B) recombinant forms among men who have sex with men in Beijing, China.

We report here two novel HIV-1 recombinant forms (CRF01_AE/B) isolated from two HIV-positive male subjects infected through homosexual contact in Beijing, China. Recombination contributes substantially to the genetic diversity of HIV-1, and is likely to occur in populations in which multiple subtypes circulate. Molecular epidemiological studies showed that subtype B, CRF01_AE, and CRF07_BC are currently cocirculating in parallel among men who have sex with men (MSM) in China, providing the opportunity for the emergence of new recombinants. Phylogenetic analysis of near full-length genome (NFLG) sequences showed that the unique recombinant forms (URFs) were composed of gene regions from CRF01_AE and subtype B. The CRF01_AE region of the recombinants clustered together with a previously described cluster 4 lineage of CRF01_AE. The B regions of both the recombinants clustered within the B strains. The two recombinants were quite similar with six breakpoints in common. These data highlight the importance of continuous surveillance of the dynamic change of HIV-1 subtypes and new recombinants among the MSM population.