Objective: To investigate the molecular epidemiology of recently diagnosed HIV-1 infection in Macao for better understanding the epidemiology in this Chinese city, in context of its relationship with other countries in Asia and the rest of the world.

Methods: Serum samples of HIV positive cases reported between 2005 and 2007 were collected from the Macao Public Health Laboratory. HIV genotype was determined by phylogenetic analysis of sequences from gag, RT, and env regions.

Results: A total of 30 HIV positive samples were genotyped. The HIV-1 viruses circulating in Macao were characterized by their relatively high genetic diversity. CRF01_AE was predominant (56%), followed by subtype B (13%), CRF12_BF (10%), G/CRF12_BF, A1/CRF10_AD and CRF07_BC, of which CRF12_BF and G/CRF12_BF were first reported in Southeast Asia. Phylogenetic analysis showed that there was no clear clustering of CRF01_AE strains but a distinct CRF12_BF cluster associated with injection drug use could be delineated.

Conclusion: The results suggested that there were multiple introductions of HIV strains in Macao that have been circulating for an extended period of time, superimposed by an outbreak in injection drug users.