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276 Identification and Characterization of Multiple Forms of Unique HIV-1 Intersubtype Recombinants in Myanmar
Y. Takebe*1, K. Motomura1, S. Kusagawa1, H. H. Lwin2, and M. Zaw2
1AIDS Res. Ctr., Natl. Inst. of Infectious Diseases, Tokyo, Japan and 2AIDS Prevention and Control Programme, Dept. of Hlth., Yangon, Myanmar
Background: Myanmar is the second largest epicenter of HIV epidemic in Southeast Asia, where 530 thousands people are estimated to be infected. HIV prevalence is particularly high in Central and Northeast Myanmar: more than 60 and 30% among IDUs and CSWs, respectively. We investigated the molecular nature of HIV strains circulating in Myanmar and the interrelationship of the epidemic to that in surrounding countries.
Methods: The nucleotide sequences of gag (p17), env (C2/V3), and RT or vif-vpu regions in HIV-1 genomes were determined for 84 specimens from Mandalay. The near full-length sequences were determined for selected isolates and the phylogenetic relationship and recombination breakpoints were analyzed.
Results: Phylogenetic analyses detected 13 subtype C (16%), in addition to the previously identified subtype B (19/84, 23%) and CRF01_AE (37/84, 44%) that are likely to be originated from neighboring Thailand. Most of subtype C in Myanmar belongs to the India-China cluster. Interestingly, the remaining 15 specimens (18%) showed discordance between gag and env subtypes, including 4 gag B/env C (B/C), 3 C/B, C/E and B/E, and 2 E/B. These discordant specimens were found most frequently among IDUs (10/34, 29%). The chimeric structures were verified in 7 specimens on the basis of recombination breakpoint analysis of the contiguous segments in HIV-1 genome. The analyses of near full-length genomes identified 3 unique forms of HIV-1 intersubtype B/C, E/B, and C/E recombinants.
Conclusions: The data suggest that multiple subtypes of B, C, and CRF01_AE are cocirculating in Central Myanmar, leading to the evolution of new forms of HIV-1 intersubtype recombinants. The multiple occurrence of unique recombinant forms suggested the ongoing recombination events between circulating subtypes and could complicate the vaccine strategies for this particular area in Asia.
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