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Classical Swine Fever Virus p7 Protein Is a Viroporin Involved in Virulence in Swine

Permanent URL:
http://handle.nal.usda.gov/10113/54545
Abstract:
The nonstructural protein p7 of classical swine fever virus (CSFV) is a small hydrophobic polypeptide with an apparent molecular mass of 6 to 7 kDa. The protein contains two hydrophobic stretches of amino acids interrupted by a short charged segment that are predicted to form transmembrane helices and a cytosolic loop, respectively. Using reverse genetics, partial in-frame deletions of p7 were deleterious for virus growth, demonstrating that CSFV p7 function is critical for virus production in cell cultures. A panel of recombinant mutant CSFVs was created using alanine scanning mutagenesis of the p7 gene harboring sequential three- to six-amino-acid residue substitutions spanning the entire protein. These recombinant viruses allowed the identification of the regions within p7 that are critical for virus production in vitro. In vivo, some of these viruses were partially or completely attenuated in swine relative to the highly virulent parental CSFV Brescia strain, indicating a significant role of p7 in CSFV virulence. Structure-function analyses in model membranes emulating the endoplasmic reticulum lipid composition confirmed that CSFV p7 is a pore-forming protein, and that pore-forming activity resides in the C-terminal transmembrane helix. Therefore, p7 is a viroporin which is clearly involved in the process of CSFV virulence in swine.
Author(s):
Douglas P. Gladue , Lauren G. Holinka , Eneko Largo , Ignacio Fernandez Sainz , Consuelo Carrillo , Vivian O'Donnell , Ryan Baker-Branstetter , Zhiqiang Lu , Xavier Ambroggio , Guillermo R. Risatti , Jose L. Nieva , Manuel V. Borca
Subject(s):
Classical swine fever virus , alanine , amino acid composition , cultured cells , endoplasmic reticulum , genes , lipid composition , microbial growth , molecular weight , mutagenesis , prediction , proteins , swine , virulence , viruses
Source:
J Virol 2012 June 15 v.86 no.12
Language:
English
Publisher:
American Society for Microbiology
Year:
2012
Collection:
Journal Articles, USDA Authors, Peer-Reviewed
File:
Download [PDF File]
Rights:
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.