Identification of Two Similar Novel HIV-1 Recombinant Forms (CRF01_AE/CRF07_BC) among Intravenous Drug Users in Guangxi, China

New kinds of HIV-1 circulating recombinant forms (CRFs) and unique recombinant forms (URFs) earn a great prevalence in China nowadays. In this study, we identified 2 similar URFs (2016GXNNIDU037 and 2019QZLSIDU253) both isolated from intravenous drug users (IDUs) in Guangxi, China. Phylogenetic analysis of the near full-length genome (NFLG) revealed 2 URFs both clustered with CRF01_AE but setting up a monophyletic branch, supporting a high bootstrap value. Bootscan analysis and subregional recombinant analysis found that the NFLG of 2016GXNNIDU037 and 2019QZLSIDU253 were both composed of CRF01_AE and CRF07_BC, with 3 CRF07_BC mosaic segments inserted into CRF01_AE backbones. The CRF01_AE segments of the 2 URFs clustered with a previously reported cluster 2 lineage of CRF01_AE. The 5 recombinant breakpoints of the 2 URFs were quite similar. Distinct from CRF01_AE/CRF07_BC URFs reported before, 2016GXNNIDU037 and 2019QZLSIDU253 are new evidence of a high genetic variety of HIV-1 in Guangxi, which may pose new challenges to HIV-1 prevention and molecular epidemiological surveillance in China.