Emergence of new forms of human immunodeficiency virus type 1 intersubtype recombinants in central Myanmar.

We have previously shown that HIV-1 env subtypes B′ (a Thai-B cluster within subtype B) and E (CRF01_AE) are distributed in Yangon, the capital city of Myanmar. However, HIV strains from the rest of country have not yet been genetically characterized. In the present study, we determined env (C2/V3) and gag (p17) subtypes of 25 specimens from central Myanmar (Mandalay). Phylogenetic analyses identified 5 subtype C (20%), in addition to 10 CRF01_AE (40%) and 4 subtype B′ (16%). Interestingly, the remaining six specimens (24%) showed discordance between gag and env subtypes; three gag subtype B′/env subtype C, one gag subtype B′/env subtype E, one gag subtype C/env subtype B′, and one gag subtype C/env subtype E. These discordant specimens were found frequently among injecting drug users (4 of 12, 33%) and female commercial sex workers (2 of 8, 25%) engaging in high-risk behaviors. The recombinant nature of these HIV-1 strains was verified in three specimens, indicating the presence of new forms of HIV-1 int...