IL1B and infection: To test this hypothesis, we performed infections of THP-1-derived macrophages using the M90T wild-type strain and the ΔybjX, ΔvirK or ΔybjXΔvirK derivatives and analyzed the concentration of IL-1β secreted by infected cells 2 hours p.i. The infection with M90TΔybjX did not significantly influence the release of IL-1β, while M90T ΔvirK caused a significant increase in the concentration of IL-1β in the supernatant (Figure 7A).