Characterization of a Novel HIV-1 Circulating Recombinant Form, CRF01_AE/B′/C (CRF96_cpx), in Yunnan, China

Currently, complex HIV-1 recombinations among the B′, C, and CRF01_AE genotypes have frequently arisen in Yunnan, China. A novel HIV-1 complex circulating recombinant form (CRF) consisting of B′, C, and CRF01_AE (CRF96_cpx) was recently characterized from three epidemiologically unlinked individuals. Two strains of them were isolated from the injecting drug users in this study, the remaining one strain (JL. RL01) was obtained from a previous report in Jilin province. Phylogenetic analysis based on near full-length genome revealed that CRF96_cpx formed a distinct monophyletic cluster supported by a high bootstrap value of 100%, distantly related to all known HIV-1 subtypes/CRFs. CRF96_cpx had a CRF01_AE backbone with three subtype B′ and C segments inserted, respectively, in the gag and pol region. Furthermore, subregion tree analysis showed that CRF01_AE backbone and subtype B segment inserted originated from a Thai-CRF01_AE lineage, whereas subtype C fragment inserted was from an India C lineage. They are different from previously documented CRF01_AE/B/C forms in its distinct backbone, inserted fragment size, and breakpoints. This highlighted the importance of continual monitoring of genetic diversity and complexity of HIV-1 strains in Yunnan, China.