Neutralizing antibody responses in Africa green monkeys naturally infectedwith simian immunodeficiency virus (SIVagm)

This study assessed the magnitude and cross-reactivity of the neutralizing antibody response generated by natural SIV infection in wild-caught African green monkeys. Neutralizing antibodies of variable potency, sometimes exce eding a titer of 1:1,000, were detected in 20 of 20 SIV-seropositive Africa n green monkeys in Kenya. Detection of those neutralizing antibodies was de pendent on the strain of virus and the cells used for assay, where the most sensitive detection was made with SIVagm1532 in Sup T1 cells. Potent neutr alization of SIVagm1532 was seen with contemporaneous autologous serum. Pot ent neutralization was also detected with laboratory-passaged SIVmac251 and SIVsmB670, but not with SIVsmE660 and two additional strains of SIVagm. Se rum samples from rhesus macaques (Macaca mulatta) experimentally infected w ith either SIVmac251 or SIVsmE660 were capable of low-level neutralization of SIVagm. These results indicate that natural infection with SIV can gener ate strain-specific neutralizing antibodies in African green monkeys. They also indicate that some neutralization determinants of SIVagm are partially shared with SIV strains that arose in sooty mangabys and were subsequently transmitted to rhesus macaques.