Onward transmission of multiple HIV-1 unique recombinant forms among men who have sex with men in Beijing, China.

BACKGROUND: Unique recombinant forms (URFs) were generated in dually-infected or multiply-infected individuals, and some of URFs can be transmitted to many people resulting in the emergence of circulating recombinant forms (CRFs). We examined whether there was evidence for onward transmission of multiple URFs among men who have sex with men (MSM) in Beijing.

METHODS: A total of 146 MSM subjects with acute/early HIV-1 infection were recruited from the Beijing PRIMO clinical cohort between September 2010 and July 2012. HIV-1 full-length gag and partial pol, env genes were amplified and sequenced separately. Phylogenetic and recombination analysis were performed to determine the viral genotypes. Single genome amplification (SGA) and direct sequencing were used to confirm onward transmission of URFs RESULTS:: CRF01_AE was the most common genotype (51.9%), followed by CRF07_BC (23.0%), subtype B (14.8%), URFs (7.4%), CRF65_cpx (2.2%), CRF55_01B (0.7%). Multiple forms of URFs were identified, including CRF01_AE/BC, CRF01_AE/B and CRF01_AE/C. Nine of the ten individuals harboring URFs were infected by onward transmission of URFs. The remained one individual was co-infected with CRF01_AE and CRF07_BC variants.

CONCLUSION: We introduced a new method to provide evidence for onward transmission of URF strains by examining the absence of inter-subtype co-infection among early infected individuals. Onward transmission of multiple URFs was found among MSM in Beijing, China. Our findings call for a program of continuous molecular surveillance and have implications to prevention programs among MSM in China.