The SL-12.1 monoclonal antibody specifically recognizes human Interferon regulatory factor 3 (IRF-3). Viral infection in mammals can lead to the induction of multiple pathways as part of the host defense mechanism. One of the major pathways activated is the JAK-STAT pathway by various interferons (IFNα and IFNβ). These IFNs exert their influence via transcriptional activation of specific target genes involved in antiviral defense, for example the chemokine ISG15 gene or the major histocompatibility complex class I and II molecules. These genes in turn are regulated by the JAK-STAT signaling pathway and through interferon regulatory factors (IRFs). IRFs are a family of transcription factors that possess a broad range of activities. IRF-3 is one of nine members which all share a common DNA binding domain which binds to an IFN stimulated response element (ISRE) found in the majority of IFN-inducible promoters. The IRF3 gene expresses a 50 kDa protein which is constitutively expressed in all tissues. The protein undergoes post-translational modification as well as dimerization and is translocated from the cytoplasm to the nucleus upon viral infection or exposure to dsRNA.