NOS2 and infection: Anti-viral IFN signaling in response to infection is capable of inducing a variety of host cell defenses targeting various aspects of virus biology, including global inhibition of translation via activation of protein kinase R (PKR), induction of RNAse L-mediated degradation of viral RNA, production of anti-viral nitric oxide through inducible nitric oxide synthase (iNOS), depletion of tryptophan via the indoleamine 2,3 dioxygenase (IDO) pathway, and upregulation of antigen presentation via major histocompatibility (MHC) complex constituents [6,7,8,9,10].