Strikingly, even systemic C. jejuni induced pro-inflammatory cytokine responses were dependent on an intact pepP gene, given that IFN-γ, TNF, MCP-1, and IL-6 concentrations were lower in serum samples following ΔpepP versus WT and pepP complemented strain infection (p < .05–0.01; Figure 8). The gene discussed is IFNG; the disease is infection.