Interferon-Stimulated Genes (ISGs)

Interferon-stimulated genes (ISGs) are a broad group of genes whose expression is upregulated in response to interferons (IFNs), which are cytokines secreted as part of the innate immune response. ISGs play essential roles in defending against viral, bacterial, and parasitic pathogens by activating diverse cellular pathways that suppress infection at nearly all stages of a pathogen’s lifecycle. ISGs encode proteins with antiviral, antiproliferative, and immunomodulatory activities. They inhibit viral entry into cells, block replication within infected cells, and prevent the release of new virions. Some ISG products degrade viral RNA or inhibit its translation; others induce apoptosis to eliminate infected cells or enhance sensitivity to natural killer cell-mediated killing. Many ISGs regulate components of the IFN signaling pathway itself—such as pattern recognition receptors (PRRs), JAK/STAT pathway proteins—amplifying or modulating the overall immune response.

Varies depending on the specific ISG, including inhibition of viral entry, replication, and release; degradation of viral RNA; induction of apoptosis; and modulation of the immune response.