Sequence analysis of env C2/V3, gag p17/p24, and pol protease regions of 25 HIV type 1 isolates from Ho Chi Minh City, Vietnam.

Env C2/V3, gag p17/p24, pol protease, and RT regions of HIV-1 isolates recently obtained from 25 HIV-1 seropositive individuals from Ho Chi Minh City (Vietnam) were studied, and genes subtypes were determined by DNA sequence analyses. Twenty-three isolates out of 25 were identified as belonging to subtype E, now recognized as circulating recombinant form 1 (CRF01_AE). The motif at the top of the V3 loop (generally GPGQ) was then preceded by an isoleucine or a methionine (M) residue; the M residue might be a local signature of Vietnamese E isolates compared to Thai E viruses. Two isolates (8%) were shown to be intersubtype recombinants: one E/B and one CRF02_AG(IBNG)/D. The polymorphism of pol protease was considered only for CRF01_AE isolates and is clearly different from that recorded for B viruses with substitutions at positions 13, 35, 36, 41, 69, and 89.