High proportion of unrelated HIV-1 intersubtype recombinants in the Mbeya region of southwest Tanzania

Background: In Mbeya, a rural region of southwest Tanzania, HIV-1 subtypes A, C and D have been co-circulating since the early 1990s. Objective: To define to what extent the co-existence of subtypes has led to recombinant HIV-1 strains and whether there is evidence for epidemic sprea d of any circulating recombinant form. Methods: Nine HIV-1-seropositive young adults from Mbeya Town with no evide nt high-risk behaviour contributed peripheral blood mononuclear cells for t his study. Nine virtually full-length-genome-sequences were amplified from this DNA and phylogenetically analysed. Results: Out of the nine samples, t wo were subtype A (22%), two were subtype C (22%) and five were recombinant s (56%): four A/C recombinants and one C/D recombinant. None of the recombi nants were related to each other; all of them had different mosaic structur es. Most of the genome in the recombinants was subtype C. Conclusion: A high proportion of unrelated intersubtype recombinants, none of them apparently spreading in the population, may be present in southwest Tanzania. (C) 2001 Lippincott Williams & Wilkins.