Identification of an LGP2-associated MDA5 agonist in picornavirus-infected cells

Elife. 2014 Feb 18:3:e01535. doi: 10.7554/eLife.01535.

Abstract

The RIG-I-like receptors RIG-I, LGP2, and MDA5 initiate an antiviral response that includes production of type I interferons (IFNs). The nature of the RNAs that trigger MDA5 activation in infected cells remains unclear. Here, we purify and characterise LGP2/RNA complexes from cells infected with encephalomyocarditis virus (EMCV), a picornavirus detected by MDA5 and LGP2 but not RIG-I. We show that those complexes contain RNA that is highly enriched for MDA5-stimulatory activity and for a specific sequence corresponding to the L region of the EMCV antisense RNA. Synthesis of this sequence by in vitro transcription is sufficient to generate an MDA5 stimulatory RNA. Conversely, genomic deletion of the L region in EMCV generates viruses that are less potent at stimulating MDA5-dependent IFN production. Thus, the L region antisense RNA of EMCV is a key determinant of innate immunity to the virus and represents an RNA that activates MDA5 in virally-infected cells. DOI: http://dx.doi.org/10.7554/eLife.01535.001.

Keywords: EMCV; LGP2; MDA5; RIG-I-like receptors; antiviral immunity; picornavirus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chlorocebus aethiops
  • DEAD-box RNA Helicases / genetics
  • DEAD-box RNA Helicases / metabolism*
  • Encephalomyocarditis virus / drug effects
  • Encephalomyocarditis virus / genetics
  • Encephalomyocarditis virus / immunology
  • Encephalomyocarditis virus / metabolism*
  • Gene Expression Regulation, Viral
  • HEK293 Cells
  • HeLa Cells
  • Host-Pathogen Interactions
  • Humans
  • Immunity, Innate
  • Influenza A virus / genetics
  • Influenza A virus / metabolism
  • Interferon-Induced Helicase, IFIH1
  • Interferons / genetics
  • Interferons / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mutation
  • RNA Helicases / genetics
  • RNA Helicases / metabolism*
  • RNA, Antisense / genetics
  • RNA, Antisense / metabolism*
  • RNA, Viral / genetics
  • RNA, Viral / metabolism*
  • Receptor, Interferon alpha-beta / deficiency
  • Receptor, Interferon alpha-beta / genetics
  • Signal Transduction
  • Transfection
  • Vero Cells
  • Virus Replication

Substances

  • Ifnar1 protein, mouse
  • RNA, Antisense
  • RNA, Viral
  • Receptor, Interferon alpha-beta
  • Interferons
  • DHX58 protein, human
  • Dhx58 protein, mouse
  • IFIH1 protein, human
  • Ifih1 protein, mouse
  • DEAD-box RNA Helicases
  • Interferon-Induced Helicase, IFIH1
  • RNA Helicases