FIG. 1.

Phylogenetic analysis of the V3-V4 region of the env gene in HIV-1 strains from infections in Harbin City. The bootstrap probability (1,000 replicates) is indicated at the corresponding nodes of the tree. The scale bar indicates the evolutionary distance of 5% (0.05 substitutions per site). The reference sequences of subtypes A–D, F–H, J, K, CRF01_AE, CRF07_BC, and CRF08_BC were obtained from the HIV database (www.hiv.lanl.gov/). The black solid circles, black diamonds, and black triangles of the sequences represent men who have sex with men (MSM), heterosexuals, and former plasma donors/blood transfusion (FPD/BT) recipients, respectively, and the open box of sequence represents intravenous drug user (IDU) analyzed in this study.