ELISA measurements of ex vivo secretions verified that the ceca of Il18−/− mice failed to produce IL-18 under control or infection conditions (Fig S1A) and showed that IL-18 deficiency did not affect IL-22 release, as WT and Il18−/− mice displayed comparable IL-22 secretion levels under basal and infection conditions (Fig S1B). This evidence concerns the gene IL22 and infection.