Interferon beta (IFN-β) is a type I interferon that plays a critical role in the immune response to viral infections and other pathogens. In mice, IFN-β is produced by various cell types, including fibroblasts, macrophages, and dendritic cells, in response to viral infection or other stimuli. Upon secretion, IFN-β binds to the interferon alpha/beta receptor (IFNAR) on target cells, leading to the activation of signaling pathways that induce the expression of interferon-stimulated genes (ISGs). These ISGs have antiviral, immunomodulatory, and anti-proliferative effects, contributing to the host defense against viral infections and the regulation of immune responses. IFN-β is also used as a therapeutic agent for the treatment of multiple sclerosis due to its immunomodulatory properties.