Proinflammatory cytokines, IL-1β and IL-18, increased in the sera of STM-WT infected mice at 1 d p.i. With the prolongation of infection, concentration of the two cytokines in the sera of STM-WT infected mice decreased, while they were still higher than those in STM-ΔspvB infected mice (Supplementary Figure S4E & S4F). This evidence concerns the gene IL18 and infection.