IL18 and infection: RT-PCR revealed that mRNA levels of the pro-inflammatory cytokines IFN-γ, TNF-α, IL-6, IL-10, and IL-18 from liver homogenates of animals inoculated with RRV on DOL 0 (representative of early infection) were all significantly elevated compared to those from control animals 7 days after injection (p<0.05) (Figure 4).