Remarkably, infection with WT and pepP complemented strains, but not with ΔpepP resulted in increased concentrations of nitric oxide, IFN-γ, and TNF in mesenteric lymph nodes (MLN) (p < .05–0.001; Figure 5d–e), and similar differences were obtained for IFN-γ and TNF levels in ileal biopsies (p < .01–0.001; Supplemental Figure S6). The gene discussed is TNF; the disease is infection.