Recombinant characteristics of three novel HIV-1 second-generation recombinant forms composed of CRF01_AE and CRF07_BC isolated in Hebei province, China.

Human immunodeficiency virus 1 (HIV-1) is a fast-evolving, genetically diverse virus. The HIV-1 evolution rate is also significantly influenced by the frequency of HIV-1 spread in a population. Transmission via homosexual contact has become the predominant transmission route, leading to an increase in the HIV-1 epidemic in Hebei province, China. In this study, we report three novel HIV-1 CRF01_AE/CRF07_BC recombinant forms isolated from three men who have sex with men (MSM) in the cities of Shijiazhuang (20747) and Langfang (20809 and 20820). Phylogenetic analysis based on HIV-1 near-full-length genome (NFLG) sequences indicated that the three novel recombinant forms formed a distinct monophyletic branch that was separate from all known HIV-1 subtypes and circulating recombinant forms (CRFs). Breakpoint analysis showed that the three NFLGs displayed different recombinant patterns. NFLGs 20747 and 20809 had a recombinant pattern with subtype CRF01_AE gene fragments inserted into a CRF07_BC backbone, spanning from the gag to env gene regions, whereas NFLG 20820 had a recombinant pattern with subtype CRF07_BC gene fragments inserted into a CRF01_AE backbone. Subregion phylogenetic analysis confirmed that these three NFLGs comprised CRF01_AE and CRF07_BC. Our findings confirm the emergence of novel recombinant forms and highlight the need for continuous monitoring of the diversity of HIV-1 among sexually active populations, especially MSM, to better control the HIV-1 epidemic.