IRF3 (Interferon Regulatory Factor 3) is a member of the IRF family, mainly composed of a DNA-binding domain and a regulatory domain. IRF3 is primarily located in the cytoplasm but translocates to the nucleus upon activation. It plays a critical role in antiviral immune responses by recognizing double-stranded RNA resulting from viral infections, activating downstream signaling pathways such as TBK1/IKKε, leading to IRF3 phosphorylation, dimerization, and nuclear translocation, thereby inducing the expression of interferons and other antiviral genes. The expression of IRF3 is specific in different cells and tissues, and mutations or dysregulation in its gene expression are associated with resistance to viral infections and the occurrence and development of certain autoimmune diseases.