title: sGP serves as a structural protein in Ebola virus infection.
abstract: BACKGROUND
  sGP, which is perceived as nonstructural, secretory glycoprotein, shares 295 amino acids at its N-terminal with GP(1,2), which include the specific residue necessary to interact with GP(2). In the present study, we tested whether the sGP protein of Zaire ebolavirus (ZEBOV) could substitute for GP(1) and form a complex with GP(2), thus serving as a structural protein.
  
  
  METHODS
  We expressed ZEBOV GP(1,2), VP40, and NP proteins, together with sGP protein, from expression plasmids and examined the resultant virus-like particles by using Western blot. Cells expressing GP(2) in combination with either GP(1) or sGP were analyzed by using flow cytometry with the KZ52 antibody, which recognizes a GP(1,2) conformational epitope. A VSV pseudotype, VSVΔG*, which expresses a GFP reporter gene instead of the G protein, was used to produce pseudotyped viruses encoding sGP and variants of GP to test the contribution of sGP to infectivity.
  
  
  RESULTS
  Western blot and flow cytometric analyses suggested the existence of a covalently linked sGP-GP(2) molecule. VSVΔG*(sGP + GP(2)) and VSVΔG*(GP(1,2)) infected Vero E6 cells and were neutralized by the KZ52 antibody. Overexpression of sGP reduced the titer of VSVΔG*(GP(1,2)).
  
  
  CONCLUSIONS
  ZEBOV sGP can substitute for GP(1), forming a sGP-GP(2) complex and conferring infectivity. Our studies suggest a novel role for sGP as a structural protein.
authors: Division of Virology, Department of Microbiology and Immunology, University of Tokyo, Japan.
authors: Ayaka
authors: A
authors: Iwasa
authors: Masayuki
authors: M
authors: Shimojima
authors: Yoshihiro
authors: Y
authors: Kawaoka
mesh_terms: D000818:Animals; D000914:Antibodies, Viral; D015153:Blotting, Western; D002522:Chlorocebus aethiops; D029043:Ebolavirus / Q000502:physiology*; D005434:Flow Cytometry; D015967:Gene Expression Regulation, Viral / Q000502:physiology; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D008562:Membrane Glycoproteins; D010957:Plasmids; D014709:Vero Cells; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D015678:Viral Structural Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000914:Antibodies, Viral; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D014764:Viral Proteins; D015678:Viral Structural Proteins