Molecular genetic characterization of a novel HIV-1 circulating recombinant form (CRF205_0107) among men who have sex with men in Hangzhou, China.

INTRODUCTION: Circulating recombinant forms (CRFs) play a critical role in the global transmission of HIV-1. In China, where CRF01_AE and CRF07_BC are the predominant circulating strains, second-generation recombinant viruses derived from these two CRFs are continually emerging. This study identified a novel CRF derived from CRF01_AE and CRF07_BC, designated CRF205_0107, and analyzed its genomic structure, parental lineages, and coreceptor usage.

METHODS: A dataset of HIV-1 pol gene sequences was analyzed to screen for suspected unique recombinant clusters in Hangzhou, China. Plasma samples from HIV-1 infected individuals without known epidemiological linkages were selected for in-depth investigation. Near-full-length genomes (NFLGs) were generated using a two-segment amplification strategy. BLAST searches were conducted to detect highly homologous sequences. SimPlot software was used to analyze recombination patterns. Further validation was performed by constructing maximum-likelihood (ML) trees using IQ-TREE, while BEAST was employed to estimate the probable time of origin of the parental strains. Coreceptor tropism was predicted based on V3-loop sequences using the Geno2pheno algorithm.

RESULTS: Four HIV-1 NFLGs were obtained. BLAST analysis revealed that a previously reported NFLG sequence (Accession No. OP921950) from a man who has sex with men (MSM) individual in Hebei Province shared 98% similarity. Phylogenetic analysis demonstrated that these sequences formed a distinct monophyletic clade with 100% bootstrap support. Recombination analysis indicated that all five genomes shared a highly similar recombination pattern. Sub-regional phylogenetic analysis revealed that segments derived from CRF01_AE and CRF07_BC all clustered with the lineage associated with Chinese MSM (CRF01_AE_C4, CRF07_BC_N). Bayesian analysis estimated that CRF205_0107 originated around 2017-2018. Coreceptor tropism analysis based on the V3 loop indicated that all five NFLGs were CXCR4-tropic.

DISCUSSION: The emergence of CRF205_0107 provides further evidence that second-generation HIV-1 recombinants involving CRF01_AE and CRF07_BC are frequently generated in China, reflecting an increasingly complex HIV-1 epidemic among MSM populations. This complexity may further drive the accelerated spread of HIV-1. These findings underscore the importance of strengthening the identification and molecular epidemiological surveillance of CRF01_AE/CRF07_BC recombinant viruses, and highlight the urgency of curbing HIV-1 transmission among MSM in China.