Activity is proposed to be involved in viral evolution; therefore, we attempted to study the possible involvement of APOBEC family protein-mediated G to A mutation in the positive selection of Env amino acid residues. APOBEC3G and APOBEC3F are involved in GG-AG [41] and GA-AA mutations [42], respectively. We manually detected GGAG, GA-AA, GC-AC and GT-AT mutations, and found one of these mutation