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 elucidate the origins and evolution of immunodeficiency viruses. During a serological survey in Cameroon, we screened 25 wild-born guereza colobus monkeys (#Colobus guereza$) and identified 7 with HIV/SIV cross-reactive antibodies. In this study, we describe a novel lentivirus, named SIVcol, prevalent in guereza colobus monkeys. Genetic analysis revealed that SIVcol was very distinct from all other known SIV/HIV isolates, with average amino acid identities of 40% for Gag, 50% for Pol, 28% for Env, and around 25% for proteins encoded by five other genes. Phylogenetic analyses confirmed that SIVcol is genetically distinct from other previously characterized primate lentiviruses and clusters independently, forming a novel lineage, the sixth in the current classification. #Cercopithecinae$ monkeys (Old World monkeys) are subdivided into two subfamilies, the #Colobinae$ and the #Cercopithecinae$, and, so far, all #Cercopithecidae$ monkeys from which lentiviruses have been isolated 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. (Résumé d'auteur