IL4 and infection: As infection progressed to 7, 14, and 21 dpi, we observed marked reductions in multiple cytokines (including interleukin-1 β [IL-1β] and IL-4) and leukocytes (including CD45+ cells and alveolar macrophages) in mar1Δ mutant strain-inoculated lungs compared to WT strain-inoculated lungs (Fig. 4A and B; Fig. S6 and S7).