IFNG and bacterial pneumonia: Interferon-γ may not be necessary during IAV infection and may in fact be detrimental, e.g., nitrogen oxide synthase 2 deficient (NOS2−/−) mice are more protected from IAV [44], and Sun and Metzger demonstrated that treatment with an anti-IFNγ mAb clone XMG1.2 had little effect on the course of the viral infection, but inactivation of IFN-γ protected against secondary bacterial pneumonia [45].