Global Transmission of Human Immunodeficiency Virus 1 Subtype C and Its Impact on the Circulation of B/C Recombination Strains in China

This study aimed to reconstruct the origin and worldwide epidemic history of human immunodeficiency virus(HIV)1 subtype C and comprehend how HIV-1 subtype C was introduced into and spread throughout China in the formof B/C recombinant strains.Envelope sequences ofHIV-1 subtype C and some other subtypes deposited before December 31,2020 were downloaded from the Los Alamos HIV Database and the Chinese National Center for AIDS/STD Control and Prevention Database.The available sequences were screened for quality,and Bayesian analysis was used to build the maximum clade credibility evolutionary tree to analyze and judge the origin and spread of HIV-1 subtype C.HIV-1 subtype C originated in central Africa around 1952,then spread to southern Africa around 1969 and to eastern Africa around 1973.HIV-1 subtype C fromsouthern Africa was introduced into India in 1977.HIV-1 subtype C of eastern Africa was introduced into Brazil in 1987.Indian HIV-1 subtype C was exported to China in three migration events during the period from 1986 to 1989.The two predominant recombinants in China(CRF07_BC and CRF08_BC)emerged in 1988 and 1990,respectively.Other B/C recombinants,namely,CRF64_BC,CRF61_BC and CRF62_BC,originated in 1993,2002 and 2000,respectively.Our study has reconstructed the global origin and evolutionary history of HIV-1 subtype C.In addition,our study demonstrated that the Chinese HIV-1 subtype C originated from three related Indian lineages around the mid to late 1980s and,since then,has formed some B/C recombinants with subtype B that caused a widespread epidemic in China.