Isolation ofa Simian Immunodeficiency VirusRelated toHuman Immunodeficiency VirusType2froma WestAfrican PetSootyMangabey

Two of25healthy petsootymangabey(SM)monkeys(Cercocebus atys) living inWestAfrica were seropositive byimmunoblot whensurveyed forantibody tosimianimmunodeficiency virusofmacaques (SIVmac). SIVsmLIB1 was isolated fromone ofthepetsootymangabeys. Nucleotide sequencedatashowed thatthis isolate isa memberoftheSIVsm/human immunodeficiency virus type2(HIV-2)/SIVmac group of primate lentiviruses. Furthermore, sequencecomparisons revealed extensive genetic diversity among SIVsm isolates similar tothatobserved previously inSIVisolates fromnaturally infected African greenmonkeys. Theseobservations provide additional evidence formonkey-human cross-species transmission ofSIVsmasthe sourceofHIV-2infection ofhumans.