− Recognize the nucleoproteins or (nucleo-)capsid proteins of different viruses − Provide a molecular signature to distinguish between host and non-host mRNAs during viral infection − Sensor viral single-stranded RNAs (ssRNAs) and inhibit expression of viral mRNAs − MX1: potential suppressive effect on the activity of viral ribonucleoprotein complex and its GTPase − MX2: may be effective in repressing viral replication, transcription, and nucleocapsid shuttling. This evidence concerns the gene MX1 and viral infectious disease.