IL-17 KO mice infected with H5N1 influenza virus displayed reduced weight and higher mortality. (a, b) Following challenge with 10LD50 influenza virus VN1194, IL-17 KO mice (black lines) showed a significantly lower survival rate (a, n=33 in wild-type group, n=27 in IL-17 KO group) and more weight loss (b, n=4 in each group) compared to wild-type mice (grey lines). (c) Viral load in the lungs at 5 dpi was measured by real-time PCR using primers for the NP gene (n=4 in each group). *P<0.05, ***P<0.001. dpi, days post-infection; KO, knockout; LD50, 50% lethal dose; NP, nucleoprotein.