NLRP3 and infection: Despite a lack of a role for the NLRP3 inflammasome during Δ6 Yptb infection of human IECs (Fig. S4A), Yptb lacking both YopE and YopH (ΔyopEH Yptb) elicited significantly elevated IL-18 release in Caco-2 cells, indicating that combinatorial loss of both YopE and YopH was sufficient to induce inflammasome activation in human IECs (Fig. 4B).