Frequency of HIV type 1 dual infection and HIV diversity: analysis of low- and high-risk populations in Mbeya Region, Tanzania.

HIV-1 diversity, frequency of recombinants, and dual infection were determined in two populations with different HIV risk behavior. A high-risk cohort of 600 female bar workers and a normal-risk population of 1,108 antenatal clinic attendees and blood donors were recruited. Behavioral data were assessed and blood for HIV- 1 diagnosis and genotyping was sampled. HIV-1 subtypes were defined through the multiregion hybridization assay (MHA(acd)). HIV-1 prevalence differed significantly among the two populations. The prevalence was 67.8% in the population of bar workers and 17% in the normal-risk population (antenatal care attendees and blood donors). Within the normal-risk population the HIV-1 prevalence was lowest in the group of volunteer blood donors. The frequency of HIV-1 infection in women was 1.7 times higher than in men. The overall subtype distribution was A (8.5%), C (40.8%), D (3.8%), AC (25.4%), AD (5.4%), CD (8.8%), and ACD (7.3%). In the high-risk population there was a higher percentage of HIV-1 recombinant strains (54% vs. 40%, p < 0.05) and a higher frequency of dual infections (19% vs. 9%, p < 0.02) compared to the normal-risk population. High-risk populations may play an important role in the evolution of HIV, as they can provide an opportunity for the virus to coinfect, recombine, and adapt to the host-specific genetic background.