EP300 and viral infectious disease: Upon virus infection, IRF3 undergoes C-terminal phosphorylation and dimerization and then translocates into the nucleus, subsequently forming a complex with the coactivators CBP/p300, and binds to the positive regulator domain (PRD) and PRD III-like elements (PRD-LEs) of the IFN-a/b promoters and ISRE sequences of targeted genes, including that encoding the cytokine RANTES and IP-10 (Lin et al., 1998; Servant et al., 2002; Yoneyama et al., 1998).