They have nonspecific antiviral activity as well as other complex effects on immunity and cell proliferation. interferons binds to a very specific cell surface receptors and affect its replication at multiple steps,  viral penetration, synthesis of viral mRNA, assembly of viral particles and their release, but the most widespread effect is direct or indirect suppression of viral protein synthesis, i.e. inhibition of translation. interfeorn receptor like JAK STAT tyrosine protein kinase receptors which on activation phosphorylate cellular proteins. These then migrate to the nucleus and induce transcription of ‘interferon-inducedproteins’ which exert antiviral effects