Notably, infection with X4550(pYA3334-SspH2-EscI) induced significantly more IL-1β and IL-18 secretion from peritoneal macrophages than that induced by X4550(pYA3334-SspH2) or X4550(pYA3334) (P < 0.05, Fig. 2a). Here, IL1B is linked to infection.