AUTHORS - Joris Hemelaar1,*, Eleanor Gouws2, Peter D. Ghys2, Saladin Osmanov3, and WHO-UNAIDS Network for HIV Isolation and Characterisation. AFFILIATIONS - 1Nuffield Department of Obstetrics and Gynaecology, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom 2Epidemiology and Analysis Division, UNAIDS, Geneva, Switzerland 3WHO-UNAIDS HIV Vaccine Initiative, World Health Organisation, Geneva, Switzerland.Objective—To estimate the global and regional distribution of HIV-1 subtypes and recombinants between 2000 and 2007. Design—Country-specific HIV-1 molecular epidemiology data were combined with estimates of the number of HIV-infected people in each country. Method—Cross-sectional HIV-1 subtyping data were collected from 65913 samples in 109 countries between 2000 and 2007. The distribution of HIV-1 subtypes in individual countries was weighted according to the number of HIV-infected people in each country to generate estimates of regional and global HIV-1 subtype distribution for the periods 2000–2003 and 2004–2007. Results—Analysis of the global distribution of HIV-1 subtypes and recombinants in the two time periods indicated a broadly stable distribution of HIV-1 subtypes worldwide with a notable increase in the proportion of circulating recombinant forms (CRFs), a decrease in unique recombinant forms (URFs), and an overall increase in recombinants. In 2004–2007, subtype C accounted for nearly half (48%) of all global infections, followed by subtypes A (12%) and B (11%), CRF02_AG (8%), CRF01_AE (5%), subtype G (5%) and D(2%). Subtypes F, H, J and K together cause fewer than 1% of infections worldwide. Other CRFs and URFs are each responsible for 4% of global infections, bringing the combined total of worldwide CRFs to 16% and all recombinants (CRFs plus URFs) to 20%. Conclusions—The global and regional distributions of individual subtypes and recombinants are broadly stable, although CRFs may play an increasing role in the HIV pandemic. The global diversity of HIV-1 poses a formidable challenge to HIV vaccine development.2030-01-01