Characterization of a novel simian immunodeficiency virus from guereza colobus monkeys (Colobus guereza) in Cameroon: A new lineage in the nonhuman primate lentivirus family

Exploration of the diversity among primate lentiviruses is necessary to elu cidate the origins and evolution of immunodeficiency viruses. During a sero logical survey in Cameroon, we screened 25 wild-born guereza colobus monkey s (Colobus guereza) and identified 7 with HIV/SIV cross-reactive antibodies . In this study, we describe a novel lentivirus, named SIVcol, prevalent in guereza colobus monkeys. Genetic analysis revealed that SIVcol was very di stinct from all other known SIV/HIV isolates, with average amino acid ident ities of 40% for Gag, 50% for Pol, 28% for Env, and around 25% for proteins encoded by five other genes. Phylogenetic analyses confirmed that SIVcol i s genetically distinct from other previously characterized primate lentivir uses and clusters independently, forming a novel lineage, the sixth in the current classification. Cercopithecidae monkeys (Old World monkeys) are sub divided into two subfamilies, the Colobinae and the Cercopithecinae, and, s o far, all Cercopithecidae monkeys from which lentiviruses have been isolat ed belong to the Cercopithecinae subfamily. Therefore, SIVcol from guereza colobus monkeys (C. guereza) is the first primate lentivirus identified in the Colobinae subfamily and the divergence of SIVcol may reflect divergence of the host lineage.