To directly assess the contribution of IFN-λ to the protection from influenza virus-induced lung disease, we generated IL28Rα0/0 mice carrying functional Mx1 alleles by crossbreeding of appropriate mouse strains and compared the fate of wild-type and IL28Rα0/0 mice after challenge with 5×104 plaque-forming units (pfu) of SC35M. Here, MX1 is linked to lung disorder.