IL9 and infection: The expression levels of Eotaxin/CCL11, IL-2, IL-5, IL-9, and the vascular endothelial growth factor (VEGF) were not significantly different among the three mouse groups throughout the experimental period, except that the expression levels of VEGF in aged BALB/c mice in the middle phase of infection were lower than those in young C57BL/6 J mice (Supplementary Fig. 2).