Drug resistance testing provides evidence of the globalization of HIV type 1: a new circulating recombinant form.

To monitor HIV-1 diversity in Argentina, a phylogenetic-based analysis of HIV-1 partial pol sequences obtained for resistance testing in 587 treatment failure patients was performed in Buenos Aires city between 2001 and 2003. HIV-1 RNA was isolated from plasma samples and partial pol fragments amplified by RT-PCR. Sequences were obtained by automated sequencing. Phylogenetic analysis was performed and recombination patterns characterized. A total of 299 sequences grouped into clade B (50.94%) and 284 were B/F recombinants (48.38%). Four sequences were grouped into clades A, C, and F (0.68%). The clade C sample, 96105, was found to be a BC recombinant and samples 103396 and 104575 showed the same mosaic pattern with Kisii5009 from Kenya and 97KR004 from Korea, previously described as A2D recombinants. With the presence of two full-length genomes, one from Kenya and one from Korea, and now two partial genomes from Argentina, this recombinant is designated CRF16_A2D. Its presence on three continents shows that CRF16_A2D has a global distribution.