The HIV epidemic in the amazon basin is driven by prototypic and recombinant HIV-1 subtypes B and F

This paper describes genetic subtypes of HIV-1 found in blood samples from 31 HIV-1-infected people who visited the Counseling and Testing AIDS Center of Institute de Medicina Tropical in Manaus, Brazil. Manaus, the main city in Brazil's Amazon Basin, is also the closest urban connection for more th an 100,000 Indians living in the rain forests of this region. Although to d ate there is no evidence of increased incidence of HIV-1 infection among th e indigenous population, our understanding of both the prevalence and natur e of the epidemic in the region as a whole is limited. From the 31 samples analyzed by C2V3 sequencing, we found almost equal proportions of HIV-1 str ains belonging to subtype B (n = 16; 51.6%) and subtype F (n = 15; 48.4%), a finding that differs from results from previous studies conducted in urba n areas of southeastern Brazil. We also observed the presence of the GWGR a mino-acid sequence in the critical tetra-peptide crown of the env V3 loop i n the HIV-1 subtype B samples analyzed. Among these samples, we also found 14 mosaic genomes (45.16%) in which different combinations of subtypes B, C , and F were identified between the p24 gag, pro, and env regions. Our data support the hypothesis that the Amazonian HIV-1 infections linked to the u rban epidemic in southeastern Brazil. The genetic diversity and the prevale nce of mosaic genomes among the isolates in our study confirm an integral r ole of recombination in the complex Brazilian epidemic.