In pathogenic SIVmac251 infection, marked increases in essentially all cytokines/chemokines tested were detected in plasma through 56 days postinfection, and significantly elevated levels of IL-1β, IL-6, IL-10 and TNF-α, were detected at day 21 infection in SIVmac251-infected macaques compared with SHIV162P3 infected macaques. This evidence concerns the gene IL1B and infection.