title: Effect of cell polarization on hepatitis C virus entry.
abstract: The primary reservoir for hepatitis C virus (HCV) replication in vivo is believed to be hepatocytes within the liver. Three host cell molecules have been reported to be important entry factors for receptors for HCV: the tetraspanin CD81, scavenger receptor BI (SR-BI), and the tight-junction (TJ) protein claudin 1 (CLDN1). The recent discovery of a TJ protein as a critical coreceptor highlighted the importance of studying the effect(s) of TJ formation and cell polarization on HCV entry. The colorectal adenocarcinoma Caco-2 cell line forms polarized monolayers containing functional TJs and was found to express the CD81, SR-BI, and CLDN1 proteins. Viral receptor expression levels increased upon polarization, and CLDN1 relocalized from the apical pole of the lateral cell membrane to the lateral cell-cell junction and basolateral domains. In contrast, expression and localization of the TJ proteins ZO-1 and occludin 1 were unchanged upon polarization. HCV infected polarized and nonpolarized Caco-2 cells to comparable levels, and entry was neutralized by anti-E2 monoclonal antibodies, demonstrating glycoprotein-dependent entry. HCV pseudoparticle infection and recombinant HCV E1E2 glycoprotein interaction with polarized Caco-2 cells occurred predominantly at the apical surface. Disruption of TJs significantly increased HCV entry. These data support a model where TJs provide a physical barrier for viral access to receptors expressed on lateral and basolateral cellular domains.
authors.affiliation: Division of Immunity and Infection, Institute for Biomedical Research, University of Birmingham, Vincent Drive, Birmingham B15 2TT, United Kingdom. p.balfe@bham.ac.uk.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Mee
authors.forename: Joe
authors.initials: J
authors.lastname: Grove
authors.forename: Helen J
authors.initials: HJ
authors.lastname: Harris
authors.forename: Ke
authors.initials: K
authors.lastname: Hu
authors.forename: Peter
authors.initials: P
authors.lastname: Balfe
authors.forename: Jane A
authors.initials: JA
authors.lastname: McKeating
mesh_terms: D015703:Antigens, CD / Q000032:analysis; D018938:Caco-2 Cells; D002462:Cell Membrane / Q000737:chemistry; D016764:Cell Polarity; D062445:Claudin-1; D016174:Hepacivirus / Q000502:physiology*; D006801:Humans; D008565:Membrane Proteins / Q000032:analysis; D062793:Occludin; D010750:Phosphoproteins / Q000032:analysis; D011991:Receptors, Virus / Q000032:analysis; D051122:Scavenger Receptors, Class B / Q000032:analysis; D060225:Tetraspanin 28; D019108:Tight Junctions / Q000502:physiology; D053586:Virus Internalization; D062826:Zonula Occludens-1 Protein
chemical_list: D015703:Antigens, CD; C554798:CD81 protein, human; C568108:CLDN1 protein, human; D062445:Claudin-1; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D010750:Phosphoproteins; D011991:Receptors, Virus; C495124:SCARB1 protein, human; D051122:Scavenger Receptors, Class B; C569042:TJP1 protein, human; D060225:Tetraspanin 28; D062826:Zonula Occludens-1 Protein