Molecular epidemiology of HIV-1 infection and full-length genomic analysis of circulating recombinant form 07_BC strains from injection drug users in Taiwan

Background. Previously, we reported that there was an outbreak of human immunodeficiency virus type 1 (HIV-1) circulating recombinant form (CRF) 07_BC among injection drug users (IDUs) in Taiwan in 2004. The objectives of the present study were to conduct a molecular epidemiological analysis and to characterize the full-length genome of the Taiwanese CRF07_BC. Methods. Three hundred and fifty-eight patients with HIV-1/AIDS from hospitals and 133 HIV-1-infected inmates from detention centers were recruited. DNA sequencing and phylogenetic analysis were conducted to determine subtypes and evolutionary relationships. Recombination breakpoints of 2 full-length CRF07_BC strains were elucidated using a bootscanning method. Results. Of 206 HIV-1-infected patients who received a diagnosis in 2004, 44.7% were infected with subtype B, 53.4% with CRF07_BC, and 1.5% with CRF01_AE. Ninety-eight percent (109/111) of IDUs were infected with CRF07_BC. Deletions of 7-11 amino acids in both p6^gag and p6^pol proteins were noted among the Taiwanese CRF07_BC strains. The CRF_07BC strains belonged to 2 phylogenetic clusters, and the first cluster contained only CRF07_BC strains from the southern part of Taiwan. Conclusions. The Taiwanese CRF07_BC strains had 97% full-length sequence homology with the prototype from mainland China. CRF07_BC was first introduced into the southern region in 2002 and then spread to other regions in Taiwan in 2004.