The highly virulent variola and monkeypox viruses express secreted inhibitors of type I interferon

FASEB J. 2010 May;24(5):1479-88. doi: 10.1096/fj.09-144733. Epub 2009 Dec 17.

Abstract

Variola virus (VARV) caused smallpox, one of the most devastating human diseases and the first to be eradicated, but its deliberate release represents a dangerous threat. Virulent orthopoxviruses infecting humans, such as monkeypox virus (MPXV), could fill the niche left by smallpox eradication and the cessation of vaccination. However, immunomodulatory activities and virulence determinants of VARV and MPXV remain largely unexplored. We report the molecular characterization of the VARV- and MPXV-secreted type I interferon-binding proteins, which interact with the cell surface after secretion and prevent type I interferon responses. The proteins expressed in the baculovirus system have been purified, and their interferon-binding properties characterized by surface plasmon resonance. The ability of these proteins to inhibit a broad range of interferons was investigated to identify potential adaptation to the human immune system. Furthermore, we demonstrate by Western blot and activity assays the expression of the type I interferon inhibitor during VARV and MPXV infections. These findings are relevant for the design of new vaccines and therapeutics to smallpox and emergent virulent orthopoxviruses because the type I interferon-binding protein is a major virulence factor in animal models, vaccination with this protein induces protective immunity, and its neutralization prevents disease progression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Disease Models, Animal
  • Humans
  • Immunomodulation
  • Interferon Type I / antagonists & inhibitors*
  • Monkeypox virus / immunology*
  • Monkeypox virus / metabolism
  • Monkeypox virus / pathogenicity
  • Mpox (monkeypox) / immunology*
  • Smallpox / immunology*
  • Variola virus / immunology*
  • Variola virus / metabolism
  • Variola virus / pathogenicity
  • Viral Proteins / metabolism*
  • Viral Vaccines / immunology
  • Virulence Factors / metabolism*

Substances

  • Interferon Type I
  • Viral Proteins
  • Viral Vaccines
  • Virulence Factors