IL6 and infection: At 24 h pbi, interleukin-6 (IL-6), KC, MIP-1β, and granulocyte-macrophage colony-stimulating factor (GM-CSF) were reduced during infection with all SGD mutant bacteria in IAV-infected animals (P < 0.05), while only GM-CSF was reduced with D39Δ1098 (P < 0.05) and D39ΔproB (P < 0.01) in mock-infected animals (Fig. 5 and Fig. S2 to S4).