TNF and infection: The mRNA expression of various inflammatory cytokines (Il-6, Tnf-α, Ifn-γ, and Ifn-β) and chemokines (Ccl2, Ccl4, Ccl12, Cxcl1, and Cxcl10), but not Il-1β, was elevated in the lungs at 2 dpi, in the early stage of infection (Figure 4).