Genetic characteristics of two unique recombinant forms of HIV-1 CRF01_AE/CRF07_BC by near full-length genome from men who have sex with men in Beijing, China.

Two HIV-1 infections with unassigned genotypes were identified during HIV-1 pretreatment drug resistance surveillance. The near full-length genome (NFLG) sequences of BL5040-00 and BL5085-00 were obtained and was classified as unique recombinant forms between CRF01_AE and CRF07_BC. Simplot (version 3.5) analyses showed that the two URFs shared the similar recombinant forms, and in the backbone belonging to CRF01_AE, the gag-pol, vpu, env and nef gene fragments were genetically substituted by CRF07_BC. BL5040-00, with 10 breakpoints, had 6 CRF07_BC fragments and 5 CRF01_AE fragments, while BL5085-00, with 6 breakpoints, had 4 CRF07_BC fragments and 3 CRF01_AE fragments. BL5040-00 strain had two additional recombination breakpoints in pol-vif gene. The presence of URFs suggest that the MSM population in Beijing has an active HIV epidemic and the genetic diversity of HIV-1 is complex, emphasizing molecular epidemiology and disease progression monitoring should be strengthened.