Direct antiviral activity of interferon stimulated genes is responsible for resistance to paramyxoviruses in ISG15-deficient cells

David Holthaus, Andri Vasou, Connor Bamford, Jelena Andrejeva, Christina Paulus, Richard Edward Randall, John McLauchlan, David John Hughes*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)
7 Downloads (Pure)

Abstract

IFNs, produced during viral infections, induce the expression of hundreds of IFN-stimulated genes (ISGs). Some ISGs have specific antiviral activity, whereas others regulate the cellular response. Besides functioning as an antiviral effector, ISG15 is a negative regulator of IFN signaling, and inherited ISG15 deficiency leads to autoinflammatory IFNopathies, in which individuals exhibit elevated ISG expression in the absence of pathogenic infection. We have recapitulated these effects in cultured human A549-ISG15−/− cells and (using A549-UBA7−/− cells) confirmed that posttranslational modification by ISG15 (ISGylation) is not required for regulation of the type I IFN response. ISG15-deficient cells pretreated with IFN-α were resistant to paramyxovirus infection. We also showed that IFN-α treatment of ISG15-deficient cells led to significant inhibition of global protein synthesis, leading us to ask whether resistance was due to the direct antiviral activity of ISGs or whether cells were nonpermissive because of translation defects. We took advantage of the knowledge that IFN-induced protein with tetratricopeptide repeats 1 (IFIT1) is the principal antiviral ISG for parainfluenza virus 5. Knockdown of IFIT1 restored parainfluenza virus 5 infection in IFN-α–pretreated, ISG15-deficient cells, confirming that resistance was due to the direct antiviral activity of the IFN response. However, resistance could be induced if cells were pretreated with IFN-α for longer times, presumably because of inhibition of protein synthesis. These data show that the cause of virus resistance is 2-fold; ISG15 deficiency leads to the early overexpression of specific antiviral ISGs, but the later response is dominated by an unanticipated, ISG15-dependent loss of translational control.
Original languageEnglish
Article numberji1901472
Number of pages11
JournalThe Journal of Immunology
Early online date22 Jun 2020
DOIs
Publication statusE-pub ahead of print - 22 Jun 2020

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