Human immunodeficiency virus type 1 (HIV-1) circulating recombinant form 02_AG (CRF02_AG) has a higher in vitro replicative capacity than its parental subtypes A and G.

Human immunodeficiency virus type 1 (HIV-1) circulating recombinant form (CRF) 02_AG is the predominant subtype in Cameroon, even more prevalent than the parental subtypes A and G. An important question that needs to be addressed is whether recombination in HIV-1 infection can lead to the emergence of viruses with biological advantages. The replicative capacity was investigated in peripheral blood mononuclear cells (PBMCs) of 13 R5-tropic primary HIV-1 isolates, including 5 CRF02_AG, 4 subtype A, and 4 subtype G viruses. HIV-1 subtype identity was defined by phylogeny either of the full-length genome or analysis of a combination of segments of the gag, pro, pol, and env genes followed by recombination breakpoint analysis. All viruses were grown on PBMCs for 11 days and culture supernatant was analyzed for reverse transcriptase (RT) activity and p24 production. On day 11 post-infection, CRF02_AG strains had a 1.4-1.9 times higher RT activity and reached a significantly higher level of p24 production than the parental subtypes A and G. Furthermore, the replication rate as measured by p24 production was 1.4 times higher for CRF02_AG strains compared to the subtypes A and G. This study suggests that the recombination event that led to CRF02_AG resulted in a variant with a better replicative capacity than its progenitors. This adaptation could contribute to the broader spread of HIV-1 CRF02_AG leading to its predominance in West Central Africa compared to the lower prevalence of its parental subtypes A and G. Copyright 2006 Wiley-Liss, Inc.