IL17A and infection: IL-27 dampens inflammation and mucus inducing TH17 responses seen after infection with RSV line 19 [64]; However, while RSV line 19 is known to induce potent IL-17 responses in vivo, RSV A2 does not, and depleting or treating with IL-27 locally does not appear to affect the frequency of IL-17A+ CD4 T cells.