Identification of Two Novel HIV-1 Second-Generation Recombinant Forms (CRF01_AE/07_BC) in Shaanxi, China.

Sexual contact is the main route of transmission of HIV type 1 (HIV-1) pandemic in China. New unique recombinant forms (URFs) were increasingly characterized in sexual populations in recent years. We reported two URFs identified from two male HIV-1-positive patients who were infected through sexual exposure in Shaanxi, China. Phylogenetic analyses and bootscan analyses revealed that the near full-length genomes of the two URFs were having four recombinant breakpoints, with two CRF07_BC fragments inserted into CRF01_AE backbones. The CRF01_AE fragments of the two URFs clustered with previously reported a cluster 5 lineage of CRF01_AE. The four recombinant breakpoints of the two URFs were quite similar. The emergence of the new CRF01_AE/07_BC URFs indicated the complexity genetic variability and the active epidemic of HIV-1. Much more attention should be paid to monitor the emergency of recombinant strains.