Identification of a Novel HIV-1 Second-Generation Circulating Recombinant Form (CRF193_0107) Among MSM in Hebei Province, China.

In China, the HIV-1 epidemic is predominantly dominated by the recombinant strains CRF01_AE and CRF07_BC. The high replication rate, error-prone reverse transcriptase, and frequent recombination events of HIV-1 have facilitated the emergence of circulating recombinant forms (CRFs) between these major lineages. In this study, a novel HIV-1 second-generation circulating recombinant form (CRF193_0107), consisting of CRF01_AE and CRF07_BC, was identified during routine molecular surveillance in Hebei Province, China. We successfully obtained near-full-length genome (NFLG) sequences from three samples with no epidemiological link and performed phylogenetic, recombination, and temporal evolutionary analyses. Phylogenetic analysis revealed that these NFLG sequences formed a distinct monophyletic cluster with a high bootstrap value. Recombination analysis showed that all NFLGs shared the same unique mosaic recombination pattern between CRF01_AE and CRF07_BC clades, with one CRF07_BC fragment in the vif-vpr-tat region (HXB2 positions 5,550-5,965) inserted into a CRF01_AE backbone. Further subregion phylogenetic analysis confirmed that segment I+III of CRF193_0107 originated from men who have sex with men (MSM)-associated CRF01_AE cluster 4, and segment Ⅱ from MSM-associated CRF07_BC cluster N. The temporal evolution analysis indicated that CRF193_0107 originated in 2016. The emergence of CRF193_0107 underscores the importance of monitoring HIV-1 second-generation recombinant forms (CRFs_0107), particularly the transmission and evolution among men who have sex with men (MSM).