Norovirus regulation of the innate immune response and apoptosis occurs via the product of the alternative open reading frame 4

Nora McFadden, Dalan Bailey, Guia Carrara, Alicia Benson, Yasmin Chaudhry, Amita Shortland, Jonathan Heeney, Felix Yarovinsky, Peter Simmonds, Andrew Macdonald, Ian Goodfellow

Research output: Contribution to journalArticle

127 Citations (Scopus)

Abstract

Small RNA viruses have evolved many mechanisms to increase the capacity of their short genomes. Here we describe the identification and characterization of a novel open reading frame (ORF4) encoded by the murine norovirus (MNV) subgenomic RNA, in an alternative reading frame overlapping the VP1 coding region. ORF4 is translated during virus infection and the resultant protein localizes predominantly to the mitochondria. Using reverse genetics we demonstrated that expression of ORF4 is not required for virus replication in tissue culture but its loss results in a fitness cost since viruses lacking the ability to express ORF4 restore expression upon repeated passage in tissue culture. Functional analysis indicated that the protein produced from ORF4 antagonizes the innate immune response to infection by delaying the upregulation of a number of cellular genes activated by the innate pathway, including IFN-Beta. Apoptosis in the RAW264.7 macrophage cell line was also increased during virus infection in the absence of ORF4 expression. In vivo analysis of the WT and mutant virus lacking the ability to express ORF4 demonstrated an important role for ORF4 expression in infection and virulence. STAT1-/- mice infected with a virus lacking the ability to express ORF4 showed a delay in the onset of clinical signs when compared to mice infected with WT virus. Quantitative PCR and histopathological analysis of samples from these infected mice demonstrated that infection with a virus not expressing ORF4 results in a delayed infection in this system. In light of these findings we propose the name virulence factor 1, VF1 for this protein. The identification of VF1 represents the first characterization of an alternative open reading frame protein for the calicivirus family. The immune regulatory function of the MNV VF1 protein provide important perspectives for future research into norovirus biology and pathogenesis.

Original languageEnglish (US)
Article numbere1002413
JournalPLoS Pathogens
Volume7
Issue number12
DOIs
StatePublished - Dec 2011

Fingerprint

Norovirus
Innate Immunity
Open Reading Frames
Apoptosis
Viruses
Virus Diseases
Infection
Proteins
Reverse Genetics
Reading Frames
RNA Viruses
Virulence Factors
Virus Replication
Names
Virulence
Mitochondria
Up-Regulation
Macrophages
Genome
RNA

ASJC Scopus subject areas

  • Microbiology
  • Parasitology
  • Virology
  • Immunology
  • Genetics
  • Molecular Biology

Cite this

McFadden, N., Bailey, D., Carrara, G., Benson, A., Chaudhry, Y., Shortland, A., ... Goodfellow, I. (2011). Norovirus regulation of the innate immune response and apoptosis occurs via the product of the alternative open reading frame 4. PLoS Pathogens, 7(12), [e1002413]. https://doi.org/10.1371/journal.ppat.1002413

Norovirus regulation of the innate immune response and apoptosis occurs via the product of the alternative open reading frame 4. / McFadden, Nora; Bailey, Dalan; Carrara, Guia; Benson, Alicia; Chaudhry, Yasmin; Shortland, Amita; Heeney, Jonathan; Yarovinsky, Felix; Simmonds, Peter; Macdonald, Andrew; Goodfellow, Ian.

In: PLoS Pathogens, Vol. 7, No. 12, e1002413, 12.2011.

Research output: Contribution to journalArticle

McFadden, N, Bailey, D, Carrara, G, Benson, A, Chaudhry, Y, Shortland, A, Heeney, J, Yarovinsky, F, Simmonds, P, Macdonald, A & Goodfellow, I 2011, 'Norovirus regulation of the innate immune response and apoptosis occurs via the product of the alternative open reading frame 4', PLoS Pathogens, vol. 7, no. 12, e1002413. https://doi.org/10.1371/journal.ppat.1002413
McFadden, Nora ; Bailey, Dalan ; Carrara, Guia ; Benson, Alicia ; Chaudhry, Yasmin ; Shortland, Amita ; Heeney, Jonathan ; Yarovinsky, Felix ; Simmonds, Peter ; Macdonald, Andrew ; Goodfellow, Ian. / Norovirus regulation of the innate immune response and apoptosis occurs via the product of the alternative open reading frame 4. In: PLoS Pathogens. 2011 ; Vol. 7, No. 12.
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