Enterovirus D68 Protease 2Apro Targets TRAF3 To Subvert Host Innate Immune Responses

J Virol. 2021 Jan 13;95(3):e01856-20. doi: 10.1128/JVI.01856-20. Print 2021 Jan 13.

Abstract

Human enterovirus D68 (EV-D68) has received considerable attention recently as a global reemergent pathogen because it causes severe respiratory tract infections and acute flaccid myelitis (AFM). The nonstructural protein 2A protease (2Apro) of EVs, which functions in the cleavage of host proteins, comprises a pivotal part of the viral immune evasion process. However, the pathogenic mechanism of EV-D68 is not fully understood. In this study, we found that EV-D68 inhibited antiviral type I interferon responses by cleaving tumor necrosis factor receptor-associated factor 3 (TRAF3), which is the key factor for type I interferon production. EV-D68 inhibited Sendai virus (SEV)-induced interferon regulatory factor 3 (IRF3) activation and beta interferon (IFN-β) expression in HeLa and HEK293T cells. Furthermore, we demonstrated that EV-D68 and 2Apro were able to cleave the C-terminal region of TRAF3 in HeLa and HEK293T cells, respectively. A cysteine-to-alanine substitution at amino acid 107 (C107A) in the 2Apro protease resulted in the loss of cleavage activity to TRAF3, and mutation of glycine at amino acid 462 to alanine (G462A) in TRAF3 conferred resistance to 2Apro These results suggest that control of TRAF3 by 2Apro may be a mechanism EV-D68 utilizes to subvert host innate immune responses.IMPORTANCE Human enterovirus 68 (EV-D68) has received considerable attention recently as a global reemergent pathogen because it causes severe respiratory tract infections and acute flaccid myelitis. The nonstructural protein 2A protease (2Apro) of EV, which functions in cleavage of host proteins, comprises an essential part of the viral immune evasion process. However, the pathogenic mechanism of EV-D68 is not fully understood. Here, we show for the first time that EV-D68 inhibited antiviral type I interferon responses by cleaving tumor necrosis factor receptor-associated factor 3 (TRAF3). Furthermore, we identified the key cleavage site in TRAF3. Our study may suggest a new mechanism by which the 2Apro of EV facilitates subversion of host innate immune responses. These findings increase our understanding of EV-D68 infection and may help identify new antiviral targets against EV-D68.

Keywords: 2Apro; EV-D68; IFN-β; TRAF3; innate immune.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Enterovirus D, Human / enzymology*
  • Enterovirus Infections / immunology*
  • Enterovirus Infections / metabolism
  • Enterovirus Infections / pathology
  • Enterovirus Infections / virology
  • HEK293 Cells
  • HeLa Cells
  • Host-Pathogen Interactions / immunology*
  • Humans
  • Immunity, Innate / immunology*
  • Interferon Type I / metabolism
  • Peptide Hydrolases / genetics
  • Peptide Hydrolases / metabolism*
  • Proteolysis
  • TNF Receptor-Associated Factor 3 / genetics
  • TNF Receptor-Associated Factor 3 / metabolism*
  • Viral Proteins / genetics
  • Viral Proteins / metabolism*

Substances

  • Interferon Type I
  • TNF Receptor-Associated Factor 3
  • TRAF3 protein, human
  • Viral Proteins
  • Peptide Hydrolases