IRF9 and cytomegalovirus infection: Previous reports indicate that HCMV infection down-regulates protein levels of JAK1, STAT2 and HLA-DR (Miller et al., 1998; Le Roy et al., 1999; Le et al., 2008), and a quantitative proteomic analysis in HFF cells indicates that HCMV infection initially induces the expression of ISGs but progressively reduces levels of proteins involved in the type I IFN pathway including RIG-I, STING, IRF3, Jak1, STAT2 and IRF9 (Weekes et al., 2014).