African swine fever virus MGF505-7R protein interacted with IRF7and TBK1 to inhibit type I interferon production

Virus Res. 2022 Dec:322:198931. doi: 10.1016/j.virusres.2022.198931. Epub 2022 Sep 18.

Abstract

African swine fever virus (ASFV) employs diverse strategies to confront or evade host type I interferon (IFN-I)-induced antiviral responses. Moreover, the mechanisms of this process are largely unknown. Here, we assessed 27 ASFV proteins to determine whether any of them suppressed the cGAS-STING pathway to facilitate immune evasion. Using dual-luciferase assays, we found that ASFV MGF505-7R suppressed the activity of the IFN-β and ISRE promoters and the expression of IFN-I and ISGs. MGF505-7R interacted with IRF7 and TBK1, degrading IRF7 by autophagy, cysteine, and proteasome pathways and TBK1 by the proteasome pathway. Moreover, TBK1 and IRF3 were phosphorylated by cGAS-STING stimulation. Finally, small interfering RNA (siRNA)-based silencing of MGF505-7R enhanced IFN-I antiviral activity. Taken together, these results preliminarily clarified the immune escape mechanism of ASFV MGF505-7R, which provides a potential target for developing antiviral agents.

Keywords: African swine fever virus; IRF7; Interferon; MGF505-7R; TBK1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • African Swine Fever Virus* / genetics
  • African Swine Fever*
  • Animals
  • Antiviral Agents / metabolism
  • Antiviral Agents / pharmacology
  • Interferon Type I*
  • Nucleotidyltransferases / metabolism
  • Proteasome Endopeptidase Complex / metabolism
  • Swine
  • Viral Proteins / genetics
  • Viral Proteins / metabolism

Substances

  • Proteasome Endopeptidase Complex
  • Viral Proteins
  • Nucleotidyltransferases
  • Interferon Type I
  • Antiviral Agents