Maximum likelihood tree of Brazilian subclade F1 strains and reference strains inferred from full-length gag-pol (A) and env (B) reading frames. Black circles show the newly sampled strains from Brazil. Trees were rooted using HIV-1 HXB2 isolate. The approximate likelihood-ratio test (aLRT) values of ≥ 70% are indicated at nodes. The scale bar represents 0.05 nucleotide substitution per site.