IFIT1 and infection: IRF3-independent expression of these same ISGs was also observed during infection with other viruses: single stranded RNA (ssRNA) Newcastle disease virus (NDV) upregulated IFIT1, IFIT2 and ISG15 in cells that could respond to but were unable to produce type I IFN (75) and IFIT1 expression could be induced during ssRNA Sendai virus (SeV) infection by IRF3 nuclear translocation in cells unable to respond to type I IFN (76).