Independent introduction of transmissible F/D recombinant HIV-1 from Africa into Belgium and The Netherlands.

Most HIV-1 subtype F viruses described so far have been isolated from individuals originating in South America, Romania, or Central Africa. Previous studies have shown that subtype F viruses from these three areas can be distinguished by phylogenetic tree analysis of various parts of the HIV genome. Subtype F strains circulating in Central Africa and classified as subgroup F2 and F3 have relatively large nucleotide distances from strains of subgroup F1, which includes some African strains, along with strains from Romania and South America. Subtype F strains have now appeared in Europe. In this study, we analyzed the complete gag gene and a large fragment of the pol gene of seven strains of African origin that represent the three F subgroups. At least five of the seven strains appear to be intersubtype recombinants. Of four strains circulating in Belgium and the Netherlands, three were F/D mosaics and the fourth harboured a G(gag)/GH(pol)/F3(env) recombinant structure. Two of the three F/D mosaics showed identical breakpoints and were independently introduced in Belgium and the Netherlands. At least two of the mosaics were further transmitted. The remaining three strains of the seven we studied were isolated from individuals in Cameroon. Two included large or smaller F1 fragments in gag and pol. The third strain was subtype D along the entire gag and pol fragment. A parental African subtype F that showed no evidence for recombination was not found.