In the CNS of WT mice, increased IFN-α1, IFN-β, TNF, IL-1α, IL-1β, IL-6, and IFN-γ mRNA levels were seen at day 4 post infection, and with the exception of IFN-α1, which decreased slightly, cytokine mRNA levels increased further by day 6 post infection (Fig. 4). Here, IL1B is linked to infection.