title: Classical swine fever virus p7 protein is a viroporin involved in virulence in swine.
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.
authors.affiliation: Plum Island Animal Disease Center, Agricultural Research Service, US Department of Agriculture, Greenport, New York, USA.
authors.forename: Douglas P
authors.initials: DP
authors.lastname: Gladue
authors.forename: Lauren G
authors.initials: LG
authors.lastname: Holinka
authors.forename: Eneko
authors.initials: E
authors.lastname: Largo
authors.forename: Ignacio
authors.initials: I
authors.lastname: Fernandez Sainz
authors.forename: Consuelo
authors.initials: C
authors.lastname: Carrillo
authors.forename: Vivian
authors.initials: V
authors.lastname: O'Donnell
authors.forename: Ryan
authors.initials: R
authors.lastname: Baker-Branstetter
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Lu
authors.forename: Xavier
authors.initials: X
authors.lastname: Ambroggio
authors.forename: Guillermo R
authors.initials: GR
authors.lastname: Risatti
authors.forename: Jose L
authors.initials: JL
authors.lastname: Nieva
authors.forename: Manuel V
authors.initials: MV
authors.lastname: Borca
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D002460:Cell Line; D006691:Classical Swine Fever / Q000821:virology*; D006692:Classical Swine Fever Virus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D013552:Swine; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014774:Virulence
chemical_list: D017361:Viral Nonstructural Proteins