IL6 and infection: In particular, levels of IFN-γ and IL-18 were increased systematically and significantly during the course of infection (Fig 3C and 3D), whereas levels of IL-6, CCL2, CCL5, CCL7, CXCL1, CXCL10 and TNF-α first increased, reaching a peak level at day 3 pi (CCL2, CXCL1, TNF-α; S4A–S4C Fig) or day 4 pi (IL-6, CCL7, CXCL10; S4D–S4F Fig) pi and then gradually declined.