Different subtype distributions in two cities in Myanmar: evidence for independent clusters of HIV-1 transmission.

A molecular epidemiological investigation was conducted in two major cities in Myanmar (Yangon and Mandalay). The study revealed a unique predominance of HIV-1 subtype B' (Thailand variant of subtype B) among injecting drug users in Yangon, indicating the strong founder effect of this variant. In contrast, multiple lineages of HIV-1 strains were found in Mandalay, leading to the evolution of various forms of intersubtype recombinants. The results showed independent clusters of HIV-1 transmission in Myanmar.