In C rodentium‐induced colitis (Table 1), CARD9 effectively controlled the virulence of C rodentium to promote pathogen eradication through both gut microbiota‐independent and microbiota‐dependent mechanisms.22 Previous studies reported that the specific intestinal IgG response was required to eliminate C rodentium infection.23 However, Card9−/− (Card9−/−→germ free) mice in this study failed to stimulate the C rodentium‐specific IgG response. The gene discussed is CARD9; the disease is colitis.