Bat Severe Acute Respiratory Syndrome-Like Coronavirus ORF3b Homologues Display Different Interferon Antagonist Activities

J Gen Virol. 2012 Feb;93(Pt 2):275-281. doi: 10.1099/vir.0.033589-0. Epub 2011 Oct 19.


The ORF3b protein of severe acute respiratory syndrome coronavirus (SARS-CoV) has a nuclear localization signal (NLS) at its C terminus and antagonizes interferon (IFN) function by modulating the activity of IFN regulatory factor 3 (IRF3). SARS-like coronaviruses (SL-CoVs) found in bats share an identical genome organization and high sequence identity for most of their gene products. In this study, ORF3b homologues were identified from three bat SL-CoV strains. These ORF3b homologues were C-terminally truncated and lacked the C-terminal NLS of SARS-CoV. IFN antagonist activities analysis demonstrated that one SL-CoV ORF3b still possessed IFN antagonist and IRF3-modulating activities. These results indicate that different ORF3b proteins display different IFN antagonist activities and this function is independent of the protein's nuclear localization, suggesting a potential link between bat SL-CoV ORF3b function and viral pathogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cell Line
  • Chiroptera / virology*
  • Humans
  • Immune Evasion
  • Interferon Regulatory Factor-3 / metabolism*
  • Interferons / antagonists & inhibitors*
  • Molecular Sequence Data
  • Nuclear Localization Signals
  • SARS Virus / immunology*
  • SARS Virus / isolation & purification
  • SARS Virus / pathogenicity
  • Sequence Homology, Amino Acid
  • Viral Proteins / genetics
  • Viral Proteins / metabolism*
  • Virulence
  • Virulence Factors / genetics
  • Virulence Factors / metabolism*


  • Interferon Regulatory Factor-3
  • Nuclear Localization Signals
  • Viral Proteins
  • Virulence Factors
  • Interferons