IL17A and infection: To examine if the increase in chemokine gene expression and neutrophil recruitment in response to the WT strain during the peak phase of infection is induced by the production of IL-17, we administered 100 μg of α-IL-17 monoclonal antibody (or rat IgG to control mice) intranasally to mice on day 3 post-inoculation with 5×105 CFU of the WT strain (a time point just prior to the observed increase in IL-17 expression – Fig. 3A).