Multiple third-generation recombinants formed by CRF55_01B and CRF07_BC in newly diagnosed HIV-1 infected patients in Shenzhen city, China.

In the evolution landscape of HIV, the coexistence of multiple subtypes has led to new, complex recombinants, posing public health challenges. CRF55_01B, first identified among MSM in Shenzhen, China, has spread rapidly across China. In this study, 47 plasma samples from newly diagnosed HIV-1 CRF55_01B patients in Shenzhen, of which the genotype was only identified by the routine HIV drug resistance test, were collected. Multiple gene regions were acquired using Sanger and next-generation sequencing methods, followed by the phylogenetic reconstruction, recombination breakpoint scanning, Bayesian molecular clock, and the prediction of coreceptors. From 47 samples, we found seven new unique recombinants formed by CRF55_01B and CRF07_BC, which shared similar breakpoints in certain gene regions and primarily utilized CCR5 receptors. All of the most recent common ancestors of subregions for these recombinants were estimated to be later than CRF55_01B and CRF07_BC, potentially suggesting they are the third-generation recombinants formed by CRF55_01B and CRF07_BC as parents. The continuous emergence of new recombinants highlights the increasing complexity of circulating strains in Shenzhen, and also suggests that subtype analysis using partial pol gene may lead to an overestimation of the major subtype strains and an underestimation of new complex HIV recombinants. Consequently, to effectively address and mitigate the complex HIV epidemic, there is an urgent need for expanded monitoring and the optimization of testing methodologies.