Overexpression experiments indicated the strong inhibitory effect on ISRE promoter activity by numerous CoV accessory proteins, such as HCoV-OC43 NS2a and NS5a, MERS-CoV NS4a and NS4b [54], as well as three PDCoV-encoded accessory proteins (NS6, NS7, NS7a); however, this inhibitory mechanism needs to be verified during virus infection. This evidence concerns the gene NRAS and viral infectious disease.