Genetic diversity of HIV-1 group M from Cameroon and Republic of Congo

We analyzed 57 HIV-1 isolates from Cameroon and the Republic of Congo, with respect to the env C2V3 and/or the pol integrase regions. The results indi cated that the topology of the pol tree correlated well with that of the en v tree for four clusters of subtype D, F G and H, suggesting that these tre es reflect the true evolution of the overall genome structures of these sub types. However, of 22 Cameroonian isolates that were classified as subtype A based on env, 20 of them diverged in their pol sequence into two lineages that were completely different from the prototypical subtype A, tentativel y designated as subtypes A1 and A2. The subtype A1 isolates (6 out of 22) w ere related in their env C2V3 regions with prototypical subtype A strain, b ut in their pol regions, they formed an independent cluster that diverged f rom known HIV-1 subtypes so far reported (except for subtypes I and J). The subtype A2 isolates (14 out of 22), which represent the major epidemic typ e of HIV-1 in Cameroon, clustered distinctly in both the env and pol trees with the recently described A/G mosaic strains from Nigeria and Djibouti. T hese two lineages were not spreading in the neighboring Republic of Congo.