IFN-γ was the only measured factor with a concentration that was significantly higher than baseline levels after PR8 infection of B10 mice, whereas the levels of multiple proinflammatory cytokines and chemokines (IFN-α, IFN-γ, TNF-α, IL-1α, IL-6, MCP-1, MIP-1β, MIP-2, and IP-10 for example) were significantly increased in DR1 mice. Here, TNF is linked to infection.