The interferon (IFN) family, including type I (IFN, IFN) and type II (IFN), refers to a group of cytokines that are capable of modulating diverse biological responses such as immune regulation, tumor inhibition, cell growth arrest, innate antimicrobial responses and promotion of adaptive immunity. Type I IFNs have long been associated with the ability to diminish virus replication, and this antiviral activity is the result of IFN-induced changes in cellular gene expression. Cellular response to IFN leads to the establishment of an antiviral state, a process that requires new mRNA and protein synthesis of many IFN-stimulated gene (ISG) products that contribute to the antiviral responses required to limit diverse virus families.

Despite the negative selective pressure on viruses exerted by IFN signaling, the very existence of successful infectious and pathogenic viruses in IFN-competent hosts demonstrates their ability to resist host defenses. In fact, many viruses have evolved adaptations to allow them to evade IFN-induced innate antiviral responses through a number of access points vulnerable to viral invaders.