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

• Published in: eLife Vol. 3; p. e01535
• Main Authors: Deddouche, Safia, Goubau, Delphine, Rehwinkel, Jan, Chakravarty, Probir, Begum, Sharmin, Maillard, Pierre V, Borg, Annabel, Matthews, Nik, Feng, Qian, van Kuppeveld, Frank J M, Reis e Sousa, Caetano
• Format: Journal Article
• Language: English
• Published: England eLife Sciences Publications Ltd 18.02.2014; eLife Sciences Publications, Ltd
• Subjects: Animals; Antisense RNA; Antiviral Agents - pharmacology; antiviral immunity; Cancer; Chlorocebus aethiops; Clonal deletion; DEAD-box RNA Helicases - genetics; DEAD-box RNA Helicases - metabolism; EMCV; Encephalomyocarditis virus - drug effects; Encephalomyocarditis virus - genetics; Encephalomyocarditis virus - immunology; Encephalomyocarditis virus - metabolism; Gene Expression Regulation, Viral; Genes; Genomes; HEK293 Cells; HeLa Cells; Host-Pathogen Interactions; Humans; Immunity, Innate; Immunology; Infections; Influenza; Influenza A virus - genetics; Influenza A virus - metabolism; Innate immunity; Interferon; Interferon-Induced Helicase, IFIH1; Interferons - genetics; Interferons - metabolism; Laboratories; LGP2; MDA5; Medical research; Mice; Mice, Inbred C57BL; Mice, Knockout; Microbiology and Infectious Disease; Mutation; Nucleotide sequence; picornavirus; Receptor, Interferon alpha-beta - deficiency; Receptor, Interferon alpha-beta - genetics; Research centers; Ribonucleic acid; RIG-I-like receptor; RNA; RNA Helicases - genetics; RNA Helicases - metabolism; RNA viruses; RNA, Antisense - genetics; RNA, Antisense - metabolism; RNA, Viral - genetics; RNA, Viral - metabolism; Signal Transduction; Statistical analysis; Transcription; Transfection; Vero Cells; Viral infections; Virus Replication; Viruses; antiviral immunity; EMCV; RIG-I-like receptors; LGP2; MDA5; picornavirus
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/elife.01535

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.