NLRC4 and infection: The recombinant bacteria expressing SspH2-EscI could significantly promote the secretion of IL-1β and IL-18 and the pyroptotic cell death of macrophages in in vitro infection when compared with bacteria expressing SspH2 only, suggesting that the intracellular recombinant Salmonella can successfully express fusion protein SspH2-EscI and the SspH2 N-terminus can be used as a signal to deliver EscI C-terminus into the host cells, resulting in activation of the NLRC4 inflammasome.