IL6 and infection: Infection with the ∆stir-2 mutant increased the expression of IL-6 (Figure 4D), IL-1β (Figure 4E), and TNF-α (Figure 4F) at 18, 24, and 48 hpi, respectively, compared with macrophages infected with the wild-type SC09 strain or the ∆stir-2 + pSTIR-2 mutant strain.