High frequency of recombinant genomes in HIV type 1 samples from Brazilian southeastern and southern regions.

We describe the genetic variability of HIV-1 subtypes and recombinant genomes in samples from southeastern and southern Brazilian regions. Phylogenetic analysis of a subset of 34 samples (8F, 7B, 7C, 2D, 1A, and 9 B" variant) based on the DNA sequencing of the env gp120 and gp41, gag p17, and nef regions confirmed the presence of nine (26.5%) potentially HIV-1 recombinant genomes. From the eight C2-V3 gp120 subtype F samples, only two seem to be pure F. One of the samples, classified as B" in the C2-V3 gp120 and as B in gp41 had the gag and nef regions clustering with subtype C. Two of seven C2-V3 subtype C samples presented distinct recombinant patterns as Bgag/Cenv/Bnef and Bgag/Cenv/Cnef. Putative recombinant breakpoints were obtained for three samples presenting discordant subtypes (F/B) between gp120 and gp41 env fragments showing that similar breakpoints could be observed between two unlinked samples (95BRRJ014 and 96BRRJ101). A higher degree of polymorphism was verified in the analysis of a subtype A sample (98BRRS058) in the C2-V3/gp41 env fragment. The intrasubtype C distance was found to be lower than that found for the other subtypes for all genomic regions. These data confirm that distinct HIV-1 subtypes and recombinant forms are actively participating in the Brazilian AIDS epidemic, and that the subtype C was introduced more recently into southern Brazil.