Interferon regulatory factors (IRFs) comprise a family of transcription factors that function within the Jak/Stat pathway to regulate interferon (IFN) and IFN-inducible gene expression in response to viral infection (1). IRFs play an important role in pathogen defense, autoimmunity, lymphocyte development, cell growth, and susceptibility to transformation. The IRF family includes nine members: IRF-1, IRF-2, ISGF3γ/p48, IRF-3, IRF-4 (Pip/LSIRF/ICSAT), IRF-5, IRF-6, IRF-7, and IRF-8/ICSBP. All IRF proteins share homology in their amino-terminal DNA-binding domains. IRF family members regulate transcription through interactions with proteins that share similar DNA-binding motifs, such as IFN-stimulated response elements (ISRE), IFN consensus sequences (ICS), and IFN regulatory elements (IRF-E) (2). IRF-7, which is functionally similar to IRF-3, is preferentially expressed in lymphoid cells and induced by virus, LPS, and IFN-α (3-5). IRF-7 plays an essential role in the induction of type I interferon in response viral infecton (6-8). Like IRF-3, IRF-7 is regulated at multiple serine phosphorylation sites near its carboxyl terminus, which are required for nuclear translocation, DNA binding, and transcriptional activity (9-11).