A. Fomsgaard et al., RELATION BETWEEN PHYLOGENY OF AFRICAN-GREEN MONKEY CD4 GENES AND THEIR RESPECTIVE SIMIAN IMMUNODEFICIENCY VIRUS GENES, Journal of medical primatology, 26(3), 1997, pp. 120-128
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.