Viral and Cellular Determinants of the Hepatitis C Virus Envelope-Heparan SulfateInteraction

Abstract

Hepatitis C virus (HCV) is a major cause of posttransfusion and community-acquired hepatitis in the world. The majority of HCV-infected individuals develop chronic hepatitis that may progress to liver cirrhosis and hepatocellular carcinoma (10). Treatment options are limited, and a vaccine to prevent HCV infection is not available (14).HCV has been classified in a separate genus (Hepacivirus) of the Flaviviridae family. The virion contains a positive-strand RNA genome of approximately 9,600 nucleotides. The genome encodes a single polyprotein of 3,010 to 3,030 amino acids that is co-and posttranslationally processed by host and viral proteases into structural and nonstructural proteins. The HCV structural proteins comprise the core protein and the two envelope glycoproteins E1 and E2 (23). HCV preferentially replicates in the cytoplasm of hepatocytes, but distinct HCV sequences have also been isolated from B cells and dendritic cells (1). Several experimental systems have suggested that virus binding and entry are mediated by envelope glycoprotein E2. Using recombinant envelope glycoproteins (35), HCV-like particles (HCV-LPs) (5), retroviral HCV pseudotype particles (HCVpp) (3), and recombinant infectious virions (22,48,54) as model systems for the first steps of viral infection, CD81 (35), scavenger receptor class B type I (SR-BI) (38), dendritic cell-specific intercellular adhesion molecule 3 grabbing-nonintegrin (DC-SIGN) (25), and the glycosaminoglycan heparan sulfate (HS) (2) have been identified as HCV receptor candidates.HS comprises a family of linear polysaccharides located at the surface of mammalian cells and in the extracellular matrix. HS varies with respect to composition and quantity among different species, cell types, tissues, and the stage of cellular development. HS consists mainly of repeating disaccharide units [GlcA-GlcNAc] n , where GlcA is glucuronic acid and GlcNAc is N-acetylglucosamine. However, these saccharides undergo N deacetylation and N sulfation of the GlcNAc residues, O sulfation at various positions, and epimerization of GlcA to iduronic acid (12). These secondary modifications give rise to an enormous structural diversity throughout the length of each chain. HS chains are attached to a core protein, forming a class of glycoproteins called proteoglycans. A number of studies have indicated the potential role of heparan sulfate proteoglycans (HSPGs) in the regulation of cell growth and transformation, differentiation processes, and cell adhesion. In hepatocytes, HSPGs are thought to bridge the extracellular matrix and the intracellular cytoskeleton (36).Microorganisms may take advantage of the widespread distribution of proteoglycans on cell surfaces by using them as ligands for their attachment to the target cell. For several viruses, including members of the Flaviviridae family such as dengue virus (9), classical swine fever (18), and tick-borne

Entry and replication of recombinant hepatitis C viruses in cell culture

“…Reporter protein Abs [109,137], ITX 5061 [134], natural ligands [135,136] Abs, soluble CD81 [9,11] Abs [142] Cldn1 peptide [143] Heparin, GAG nzymatic digestion [69,132] Abs, natural ligands, soluble LDL receptor [30,133] GAGs LDLR CD81 SR-BI Cldn1 Ocln…”

“…Clathrin-dependent endocytosis -Internalization assay [146] -Inhibition by drugs and dominant-negative mutants -Live cell microscopy with labelled HCV [154] Low pH-mediated fusion in early endosomes -Inhibitors of endosomal acidi cation -Di erent fusion assays (see main text) Attachment and receptor interaction -Cell binding assays (CHO-SR-BI, CHO-CD81, etc) [118] -Pull-down assays [152] or ELISAs [132,153] with soluble CD81 or with heparin -Cell lines for receptor complementation (see Table 1) -Lentiviral expression vectors for the 4 speci c receptors and their homologs [104,116] H + Concanamycin A, Bafilomycin A1, Chloroquine, NH 4 Cl [69,146,147] Rab5 dominant negative mutant [145,146] Eps15 dominant negative mutant, Clathrin heavy chain siRNAs, Chlorpromazine [78,[145][146][147] Abs, Ezetimibe [32] NPC1L1 EGFR…”

“…Anti-E1/E2 Abs [9,11,62,148], patient sera [9], soluble E2 [46], lectins [150,151], anti-ApoE antibodies [29], apoE peptides [149] Abs, Erlotinib, Lapatinib, Gefitinib [141] EGF, TGF-α [141] HDL [138] ApoCI [139] BLTs [138,140] Abs, Dasatinib [141] Arbidol [144] Abs [109,137], ITX 5061 [134], natural ligands [135,136] Abs, soluble CD81 [9,11] Abs [142] Cldn1 peptide [143] Heparin, GAG nzymatic digestion [69,132] Abs, natural ligands, soluble LDL receptor [30,133] GAGs LDLR CD81 SR-BI Cldn1 Ocln…”

Characterization of Hepatitis C Virus Particle Subpopulations Reveals Multiple Usage of the Scavenger Receptor BI for Entry Steps

“…Attachment of viral particles to the host cell are mediated by glycosaminoglycans (35,36) and/or the LDL receptor (17,27,29,37), although it is unclear whether such interactions subsequently lead to a productive infection. Then a set of four molecules needs to be concomitantly present on the cell surface to allow HCV entry, probably after this initial capture.…”

Hepatitis C virus and proprotein convertase subtilisin/kexin type 9: a detrimental interaction to increase viral infectivity and disrupt lipid metabolism

“…Several hepatocyte surface molecules mediate HCV binding and internalization, including CD81, SR‐B1, the dendritic cell‐specific intercellular adhesion molecule‐3‐grabbing non‐integrin (DC‐SIGN or CD209) and the liver/lymph node‐specific intercellular adhesion molecule‐3 (ICAM‐3)‐grabbing integrin (L‐SIGN or CD209L), LDLR, the asialoglycoprotein receptor (ASGP‐R) and heparan sulphate proteoglycans (HSPGs). HSPG represents the first attachment site before the interaction of the virus with the other putative receptors 25, 26. Additional entry factors have been identified including claudin‐1 (CLDN1), occludin (OCLN), Niemann‐Pick C1‐like 1 (NPC1L1), transferrin receptor 1 (TfR1), epidermal growth factor receptor (EGFR) and VLDLR 7.…”