RELATION BETWEEN PHYLOGENY OF AFRICAN-GREEN MONKEY CD4 GENES AND THEIR RESPECTIVE SIMIAN IMMUNODEFICIENCY VIRUS GENES

An apparent species-specific relatedness of SIVagm suggests a coevolut ion with their natural hosts. However, the exact species or subspecies classification of African green monkeys, AGM, is uncertain because cu rrent classification schemes rely on phenotype markers, while more def initive genetic data are lacking. In this study, the CD4 protein invol ved in tissue type recognition was genetically cloned and sequenced fr om PBMC RNA from all AGM species, including Barbados green monkeys (BG M). Phylogenetic trees were constructed that also included genomic CD4 nucleotide sequences from patas, sooty mangabeys, rhesus and pig-tail macaques, chimpanzees, and humans. Chimpanzees and humans consistentl y clustered together. Monkeys within the Cercopithecus genus formed a separate cluster which included pata monkeys, supporting its grouping as a member of Cercopithecus. Surprisingly, sooty mangabeys were genet ically more closely related to Asian macaques than to other African sp ecies, which might explain why macaques are more susceptible to infect ion by the SIVsm group than to infection by SIVagm or HIV-1 and why pa tas, on the other hand, are highly susceptible to SIVagm infection. Ba sed on CD4 genetic data, tantalus, vervets, grivets, and sabaeus forme d separate subgroups with BGM grouping closely with vervets. The branc hing order of the AGM species was related to that of their respective SIVagm env sequences. The study suggests a strong correlation between CD4 phylogeny and the susceptibility of the host species to infection by a specific lentivirus and supports the assumption of a coevolution of SIVagm and AGM. CD4 sequencing is suggested as a relevant method fo r genetic determination of primate species.