Full-length genome analysis of human immunodeficiency virus type 1 subtype C in Brazil.

The most prevalent HIV-1 clade in the global epidemics is C, and this clade is also becoming important in the Brazilian epidemics. In this study, we characterized HIV-1 subtype C variants by sequencing their near full-length genomes. DNA was extracted from six samples previously classified in our laboratory as subtype C on the basis of partial genome sequencing. Amplification was carried out by overlapping PCR followed by direct sequencing. Phylogenetic analysis of full length genomes confirmed that all isolates belonged to subtype C, which formed a highly supported monophyletic cluster and showed a nucleotide distance of 5.4%. The core promoter of all isolates contained three NF-kappaB binding motifs. Our results suggest that subtype C viruses circulating in Brazil were likely introduced recently from a unique point source. The independent clustering of Brazilian subtype C on the phylogenetic tree suggests the profile of an ideal local candidate for the development of a single subtype vaccine.