title: Characterization of hepatitis C virus interaction with heparan sulfate proteoglycans.
abstract: Hepatitis C virus (HCV) entry involves binding to cell surface heparan sulfate (HS) structures. However, due to the lipoprotein-like structure of HCV, the exact contribution of virion components to this interaction remains controversial. Here, we investigated the relative contribution of HCV envelope proteins and apolipoprotein E in the HS-binding step. Deletion of hypervariable region 1, a region previously proposed to be involved in HS binding, did not alter HCV virion binding to HS, indicating that this region is not involved in this interaction in the context of a viral infection. Patient sera and monoclonal antibodies recognizing different regions of HCV envelope glycoproteins were also used in a pulldown assay with beads coated with heparin, a close HS structural homologue. Although isolated HCV envelope glycoproteins could interact with heparin, none of these antibodies was able to interfere with the virion-heparin interaction, strongly suggesting that at the virion surface, HCV envelope glycoproteins are not accessible for HS binding. In contrast, results from kinetic studies, heparin pulldown experiments, and inhibition experiments with anti-apolipoprotein E antibodies indicated that this apolipoprotein plays a major role in HCV-HS interaction. Finally, characterization of the HS structural determinants required for HCV infection by silencing of the enzymes involved in the HS biosynthesis pathway and by competition with modified heparin indicated that N- and 6-O-sulfation but not 2-O-sulfation is required for HCV infection and that the minimum HS oligosaccharide length required for HCV infection is a decasaccharide. Together, these data indicate that HCV hijacks apolipoprotein E to initiate its interaction with specific HS structures.
  
  
  OBJECTIVE
  Hepatitis C is a global health problem. Hepatitis C virus (HCV) infects approximately 130 million individuals worldwide, with the majority of cases remaining undiagnosed and untreated. In most infected individuals, the virus evades the immune system and establishes a chronic infection. As a consequence, hepatitis C is the leading cause of cirrhosis, end-stage liver disease, hepatocellular carcinoma, and liver transplantation. Virus infection is initiated by entry of the virus into the host cell. In this study, we provide new insights into the viral and cellular determinants involved in the first step of HCV entry, the binding of the virus to host cells. We show that apolipoprotein E is likely responsible for virus binding to heparan sulfate and that N- and 6-O-sulfation of the heparan sulfate proteoglycans is required for HCV infection. In addition, the minimal HS length unit required for HCV infection is a decasaccharide.
authors.affiliation: Center for Infection & Immunity of Lille (CIIL), INSERM U1019, CNRS UMR 8204, Institut Pasteur de Lille, University of Lille Nord de France, Lille, France.
authors.forename: Yan
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Unité de Glycobiologie Structurale et Fonctionnelle, CNRS UMR 8576, Université Lille Nord de France-Université des Sciences et Technologies, Villeneuve d'Ascq, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Martinez
authors.affiliation: Center for Infection & Immunity of Lille (CIIL), INSERM U1019, CNRS UMR 8204, Institut Pasteur de Lille, University of Lille Nord de France, Lille, France.
authors.forename: Karin
authors.initials: K
authors.lastname: Séron
authors.affiliation: Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
authors.forename: Guangxiang
authors.initials: G
authors.lastname: Luo
authors.affiliation: Unité de Glycobiologie Structurale et Fonctionnelle, CNRS UMR 8576, Université Lille Nord de France-Université des Sciences et Technologies, Villeneuve d'Ascq, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Allain
authors.affiliation: Center for Infection & Immunity of Lille (CIIL), INSERM U1019, CNRS UMR 8204, Institut Pasteur de Lille, University of Lille Nord de France, Lille, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Dubuisson
authors.affiliation: Center for Infection & Immunity of Lille (CIIL), INSERM U1019, CNRS UMR 8204, Institut Pasteur de Lille, University of Lille Nord de France, Lille, France Sandrine.belouzard@ibl.cnrs.fr.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Belouzard
mesh_terms: D001057:Apolipoproteins E / Q000378:metabolism*; D002460:Cell Line; D015686:Gene Products, env / Q000378:metabolism*; D016174:Hepacivirus / Q000502:physiology*; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism*; D022781:Hepatocytes / Q000821:virology; D054884:Host-Pathogen Interactions; D006801:Humans; D011485:Protein Binding; D053585:Virus Attachment; D014779:Virus Replication
chemical_list: D001057:Apolipoproteins E; D015686:Gene Products, env; D019812:Heparan Sulfate Proteoglycans