Interferon-inducible antiviral effectors

Abstract
Interferons (IFNs) are key components of the innate immune response and the first line of defence against virus infection. Among the hundreds of IFN-induced genes, only a few have been ascribed direct antiviral activity in vivo: ISG15 (IFN-stimulated protein of 15 kDa), the Mx (myxovirus resistance) proteins, 2′,5′-oligoadenylate synthetase (OAS)-regulated ribonuclease L (RNaseL) and protein kinase R (PKR). These proteins separately block viral transcription, degrade viral RNA, inhibit translation or modify the proteasome to control all steps of viral replication. ISG15 is part of a ubiquitin-like pathway that modulates the function of numerous protein targets. The Mx proteins seem to survey exocytic events and mediate vesicle trafficking to trap viral components. The OAS-regulated RNaseL pathway degrades single-stranded RNA in virus-infected cells. PKR inhibits translation and participates in signal transduction. Additional functions of each of these proteins are still being uncovered, suggesting they have broader roles in the host immune response.