Extensive and complex HIV-1 recombination between B', C and CRF01_AE among IDUs in south-east Asia.

Objective: To investigate the subtype characterization of HIV-1 among IDUs in northern Myanmar.

Design: A molecular epidemiological investigation was conducted among IDUs in Laza and Maizayang cities of northern Myanmar.

Methods: A total of 83 HIV-1-positive serums were collected from consenting IDUs during June to August 2009. HIV-1 p17, pol, vif-env, C2V3 fragments were amplified and sequenced. Phylogenetic and bootscanning analyses were performed.

Results: A very high proportion (86.1%) of HIV-1 intersubtype recombinants and very low proportion of subtypes B' (3.8%), C (7.6%) and CRF01_AE (1.3%) were found in this HIV-infected IDUs cohort. These recombinants cover all four kinds of recombination forms formed among CRF01_AE, B and C. The B/C and CRF01_AE/B/C recombinants are the two most dominant recombinants, accounting for 54.4 and 42.6% of all cases, respectively, and indicating the ongoing generation of extensive and complex HIV-1 recombination among CRF01_AE, B' and C in northern Myanmar. Intriguingly, most recombinants have different chimeric patterns from each other, forming 64 unique recombination forms (URFs) that are quite distinct from any previously identified circulating recombinant forms (CRFs) and URFs in Asia.

Conclusion: The extremely high proportion of intersubtype recombinants, especially CRF01_AE/B'/C recombinants (42.6%), strongly suggests that northern Myanmar is a big forge for HIV-1 recombination among CRF01_AE, B' and C.