Introduction
The virulence (severity) of lentiviral infections of nonhuman primates (NHPs) can vary widely, ranging
from nonpathogenic to highly pathogenic, depending on the NHP species [1–3]. For instance, SIV
infection is pathogenic in Asian NHPs, such as rhesus (RMs), pigtailed (PTMs) and cynomolgus
macaques [1,2] and, in the absence of antiretroviral therapy (ART), progresses to AIDS; therefore,
macaques have been extensively employed as models of HIV/AIDS in humans [4–7]. Conversely, SIV
infections are nonpathogenic in African NHPs, such as African green monkeys (AGMs), sooty
mangabeys (SMs) and mandrills (MNDs) [2,8,9]. In these species, disease progression is highly
uncommon, only occurring in a handful of animals which had greatly outlived their normal life