Diverse BF recombinants have spread widely since the introduction of HIV-1 into South America.

Objective: To describe the genetic diversity of HIV-1 in South America by full genome sequencing and analysis.
Methods: Purified peripheral blood mononuclear cell DNA from HIV-infected individuals in Argentina, Uruguay and Bolivia was used to amplify full HIV-1 genomes. These were sequenced using the ABI 3100 automated sequencer and phylogenetically analysed.
Results: Twenty-one HIV-1 strains from three South American countries, 17 of which were pre-screened by envelope heteroduplex mobility assay (HMA), were studied. Ten out of 10 HMA subtype F and four out of seven HMA subtype B strains were actually BF recombinants upon full genome analysis. Two BF recombinants from Argentina and two from Uruguay had the same structure, representing a new circulating recombinant form termed CRF12_BF(ARMA159). Twelve other BF recombinants had structures related to CRF12 but with additional segments of subtype B; each was unique. BF recombinants were temporally and geographically widespread, found as early as 1986-1987 in vertically infected Argentinian children and in Argentina, Uruguay, and Bolivia.