However, several PKR-deficient cell types have reduced type-I IFN production in response to poly I:C [23], [29], [30], while PKR was demonstrated to be required for IFN-α/β production in response to a subset of RNA viruses including Theiler's murine encephalomyelitis, West Nile (WNV) and Semliki Forest virus (SFV), but not influenza, Newcastle disease, nor Sendai virus [31], [32], [33], [34]. This evidence concerns the gene EIF2AK2 and Newcastle disease.