Genomic cloning and complete sequence analysis of a highly divergent African human immunodeficiency virus isolate.

Analysis of the complete sequence of a human immunodeficiency virus (HIV) isolate (Ant70) obtained from a Cameroonian patient indicates that this virus is the most divergent strain within the HIV-1 family hitherto described. Comparison of the Pol protein, usually highly conserved within the HIV-1 family, shows only about 73% similarity with the HIVmm isolate, whereas for the more variable proteins such as envelope, similarities of 50% or lower are found. The principal neutralizing determinant (V3 loop) and the immunodominant region within gp41 also contain some unusual substitutions, which may have implications for protein function as well as for serological assays based on these regions. Phylogenetic analyses show that this isolate occupies a unique position relative to the human HIV-1 isolates and the recently described SIVcpz virus, indicating that this Cameroonian isolate may provide us with new insights into the origins of the HIV-1 family.