title: Inhibition of hepatitis C virus infection by anti-claudin-1 antibodies is mediated by neutralization of E2-CD81-claudin-1 associations.
abstract: The tight junction protein claudin-1 (CLDN1) has been shown to be essential for hepatitis C virus (HCV) entry-the first step of viral infection. Due to the lack of neutralizing anti-CLDN1 antibodies, the role of CLDN1 in the viral entry process is poorly understood. In this study, we produced antibodies directed against the human CLDN1 extracellular loops by genetic immunization and used these antibodies to investigate the mechanistic role of CLDN1 for HCV entry in an infectious HCV cell culture system and human hepatocytes. Antibodies specific for cell surface-expressed CLDN1 specifically inhibit HCV infection in a dose-dependent manner. Antibodies specific for CLDN1, scavenger receptor B1, and CD81 show an additive neutralizing capacity compared with either agent used alone. Kinetic studies with anti-CLDN1 and anti-CD81 antibodies demonstrate that HCV interactions with both entry factors occur at a similar time in the internalization process. Anti-CLDN1 antibodies inhibit the binding of envelope glycoprotein E2 to HCV permissive cell lines in the absence of detectable CLDN1-E2 interaction. Using fluorescent-labeled entry factors and fluorescence resonance energy transfer methodology, we demonstrate that anti-CLDN1 antibodies inhibit CD81-CLDN1 association. In contrast, CLDN1-CLDN1 and CD81-CD81 associations were not modulated. Taken together, our results demonstrate that antibodies targeting CLDN1 neutralize HCV infectivity by reducing E2 association with the cell surface and disrupting CD81-CLDN1 interactions.
  
  
  CONCLUSIONS
  These results further define the function of CLDN1 in the HCV entry process and highlight new antiviral strategies targeting E2-CD81-CLDN1 interactions.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U748, Strasbourg, France.
authors.forename: Sophie E
authors.initials: SE
authors.lastname: Krieger
authors.forename: Mirjam B
authors.initials: MB
authors.lastname: Zeisel
authors.forename: Christopher
authors.initials: C
authors.lastname: Davis
authors.forename: Christine
authors.initials: C
authors.lastname: Thumann
authors.forename: Helen J
authors.initials: HJ
authors.lastname: Harris
authors.forename: Eva K
authors.initials: EK
authors.lastname: Schnober
authors.forename: Christopher
authors.initials: C
authors.lastname: Mee
authors.forename: Eric
authors.initials: E
authors.lastname: Soulier
authors.forename: Cathy
authors.initials: C
authors.lastname: Royer
authors.forename: Mélanie
authors.initials: M
authors.lastname: Lambotin
authors.forename: Fritz
authors.initials: F
authors.lastname: Grunert
authors.forename: Viet Loan
authors.initials: VL
authors.lastname: Dao Thi
authors.forename: Marlène
authors.initials: M
authors.lastname: Dreux
authors.forename: François-Loïc
authors.initials: FL
authors.lastname: Cosset
authors.forename: Jane A
authors.initials: JA
authors.lastname: McKeating
authors.forename: Catherine
authors.initials: C
authors.lastname: Schuster
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Baumert
mesh_terms: D000071443:12E7 Antigen; D000906:Antibodies / Q000494:pharmacology*; D015703:Antigens, CD / Q000276:immunology* / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000276:immunology*; D062445:Claudin-1; D006526:Hepatitis C / Q000628:therapy*; D006801:Humans; D007114:Immunization; D008565:Membrane Proteins / Q000276:immunology / Q000502:physiology*; D009500:Neutralization Tests; D051122:Scavenger Receptors, Class B / Q000502:physiology; D060225:Tetraspanin 28; D019108:Tight Junctions / Q000502:physiology; D053586:Virus Internalization
chemical_list: D000071443:12E7 Antigen; D000906:Antibodies; D015703:Antigens, CD; C554798:CD81 protein, human; C061828:CD99 protein, human; C568108:CLDN1 protein, human; D015815:Cell Adhesion Molecules; D062445:Claudin-1; D008565:Membrane Proteins; C495124:SCARB1 protein, human; D051122:Scavenger Receptors, Class B; D060225:Tetraspanin 28