TNF and infection: Six days following C. jejuni infection hepatic IFN-γ, TNF-α, and IL-6 concentrations increased (p < 0.05−0.0001; Figures 8A–C), but to even higher levels upon ΔhtrA knockout mutant as compared to parental C. jejuni WT strain infection (p < 0.05; Figures 8A–C).