title: Cryo-electron microscopy and three-dimensional reconstructions of hepatitis C virus particles.
abstract: The structural details of hepatitis C virus (HCV) have been elusive because of the lack of a robust tissue culture system for producing an adequate amount of virions from infectious sources for in-depth three-dimensional (3D) structural analysis. Using both negative-stain and cryo-electron microscopy (cryoEM), we show that HCV virions isolated from cell culture have a rather uniform size of 500 A in diameter and that recombinantly expressed HCV-like particles (HCV-LPs) have similar morphologic, biophysical and antigenic features in spite of the varying sizes of the particles. 3D reconstructions were obtained from HCV-LPs with the same size as the HCV virions in the presence and absence of monoclonal antibodies bound to the E1 glycoprotein. The 3D reconstruction of HCV-LP reveals a multilayered architecture, with smooth outer-layer densities arranged in a 'fishbone' configuration. Reconstruction of the particles in complex with anti-E1 antibodies shows that sites of the E1 epitope are exposed and surround the 5-, 3- and 2-fold axes. The binding pattern of the anti-E1 antibody and the fitting of the structure of the dengue virus E glycoprotein into our 3D reconstructions further suggest that the HCV-LP E1 and E2 proteins form a tetramer (or dimer of heterodimers) that corresponds morphologically and functionally to the flavivirus E homodimer. This first 3D structural analysis of HCV particles offers important insights into the elusive mechanisms of HCV assembly and maturation.
authors.affiliation: Department of Pathology and Laboratory Medicine, The University of Texas Medical School at Houston, Houston, TX 77030, USA.
authors.forename: Xuekui
authors.initials: X
authors.lastname: Yu
authors.forename: Ming
authors.initials: M
authors.lastname: Qiao
authors.forename: Ivo
authors.initials: I
authors.lastname: Atanasov
authors.forename: Zongyi
authors.initials: Z
authors.lastname: Hu
authors.forename: Takanobu
authors.initials: T
authors.lastname: Kato
authors.forename: T Jake
authors.initials: TJ
authors.lastname: Liang
authors.forename: Z Hong
authors.initials: ZH
authors.lastname: Zhou
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000914:Antibodies, Viral / Q000276:immunology; D002478:Cells, Cultured; D020285:Cryoelectron Microscopy / Q000379:methods*; D016174:Hepacivirus / Q000302:isolation & purification / Q000648:ultrastructure*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008854:Microscopy, Electron / Q000379:methods*; D014759:Viral Envelope Proteins / Q000737:chemistry; D014771:Virion / Q000302:isolation & purification / Q000648:ultrastructure*
chemical_list: D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; C087035:E1 protein, Hepatitis C virus; D014759:Viral Envelope Proteins