HIV-1 subtype characterization and transmission among different high- risk groups in the China-Myanmar border area. Data on HIV-1 subtype characterization among IDUs and sexual-infected group were taken from refs. 1, 3, 4, 6 and 9. The grey line showed the transport routes of Burmese LDTDs, which links Ruili city (in Dehong prefecture), China and Mandalay, Myanmar. The solid arrows indicated HIV-1 transmission routes obtained by phylogeographic analyses (Figures 3, 4), and the dotted arrows indicated potential HIV-1 transmission routes that need to be verified by future studies.