title: Human monoclonal antibodies that inhibit binding of hepatitis C virus E2 protein to CD81 and recognize conserved conformational epitopes.
abstract: The intrinsic variability of hepatitis C virus (HCV) envelope proteins E1 and E2 complicates the identification of protective antibodies. In an attempt to identify antibodies to E2 proteins from divergent HCV isolates, we produced HCV E2 recombinant proteins from individuals infected with HCV genotypes 1a, 1b, 2a, and 2b. These proteins were then used to characterize 10 human monoclonal antibodies (HMAbs) produced from peripheral B cells isolated from an individual infected with HCV genotype 1b. Nine of the antibodies recognize conformational epitopes within HCV E2. Six HMAbs identify epitopes shared among HCV genotypes 1a, 1b, 2a, and 2b. Six, including five broadly reactive HMAbs, could inhibit binding of HCV E2 of genotypes 1a, 1b, 2a, and 2b to human CD81 when E2 and the antibody were simultaneously exposed to CD81. Surprisingly, all of the antibodies that inhibited the binding of E2 to CD81 retained the ability to recognize preformed CD81-E2 complexes generated with some of the same recombinant E2 proteins. Two antibodies that did not recognize preformed complexes of HCV 1a E2 and CD81 also inhibited binding of HCV 1a virions to CD81. Thus, HCV-infected individuals can produce antibodies that recognize conserved conformational epitopes and inhibit the binding of HCV to CD81. The inhibition is mediated via antibody binding to epitopes outside of the CD81 binding site in E2, possibly by preventing conformational changes in E2 that are required for CD81 binding.
authors.affiliation: Departments of Pathology, Stanford University, Stanford, CA 94304, USA.
authors.forename: K G
authors.initials: KG
authors.lastname: Hadlock
authors.forename: R E
authors.initials: RE
authors.lastname: Lanford
authors.forename: S
authors.initials: S
authors.lastname: Perkins
authors.forename: J
authors.initials: J
authors.lastname: Rowe
authors.forename: Q
authors.initials: Q
authors.lastname: Yang
authors.forename: S
authors.initials: S
authors.lastname: Levy
authors.forename: P
authors.initials: P
authors.lastname: Pileri
authors.forename: S
authors.initials: S
authors.lastname: Abrignani
authors.forename: S K
authors.initials: SK
authors.lastname: Foung
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000378:metabolism; D000914:Antibodies, Viral / Q000276:immunology*; D015703:Antigens, CD / Q000276:immunology* / Q000378:metabolism; D002460:Cell Line; D017124:Conserved Sequence; D018604:Epitope Mapping; D005838:Genotype; D016174:Hepacivirus / Q000276:immunology*; D006526:Hepatitis C / Q000276:immunology / Q000821:virology; D006801:Humans; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D060225:Tetraspanin 28; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D015703:Antigens, CD; C554798:CD81 protein, human; D008565:Membrane Proteins; D011994:Recombinant Proteins; D060225:Tetraspanin 28; D014759:Viral Envelope Proteins; C091015:glycoprotein E2, Hepatitis C virus