IFNLR1 and infection: However, when the effect of IFN-λR1 deletion was tested on an IFNAR-deficient background, It was found that whereas both the IFNAR-/- and IFN-λR1-/- mice displayed only marginally elevated viral titers in the lungs, the IFNAR/ IFN-λR1-double-deficient mice were highly compromised in their antiviral response, and were unable to control the virus and hence succumbed to infection, even with attenuated IAV strains [20].