Sequence analysis of a highly divergent HIV-1-related lentivirus isolated from a wild captured chimpanzee

Abstract

Two strains of simian immunodeficiency viruses (SIV) isolated from chimpanzees (SIV(CPZ GAB) and SIV(CPZ-GAB2)) originating from Gabon have previously been genetically characterized and shown to belong phylogenetically to the same lineage as the human immunodeficiency virus type 1 (HIV-1). We describe the sequence analysis of a third HIV-1-related virus. SIV(CPZ-ANT), isolated from a wild captured chimpanzee originating from Zaire. This virus displayed the same genetic organization as HIV-1 and was found to fall on the same lineage as HIV-1 and SIV(CPZ-GAB). Protein sequence identity with SIV(CPZ-GAB) ranged from 72% (Pol) to 48% (Env) for the structural proteins, while a particularly divergent Vpu was found (only 25% identity to SIV(CPZ-GAB)). The V3 regions of the SIV(CPZ) isolates were exceptionally conserved in contrast to the high divergence of V3 among HIV-1 isolates. However, SIV(CPZ-ANI) did not show a greater degree of sequence similarity with SIV(CPZ-GAB) than with HIV-1 isolates and represents a quite divergent outgroup of the HIV-1 lineage. Our data suggest multiple introductions of HIV-1 in the human population and shed new light on the origin of the HIV-1 pandemic.