title: Interplay between basic residues of hepatitis C virus glycoprotein E2 with viral receptors, neutralizing antibodies and lipoproteins.
abstract: Positively-charged amino acids are located at specific positions in the envelope glycoprotein E2 of the hepatitis C virus (HCV): two histidines (H) and four arginines (R) in two conserved WHY and one RGERCDLEDRDR motifs, respectively. Additionally, the E2 hypervariable region 1 (HVR1) is rich in basic amino acids. To investigate the role(s) of these residues in HCV entry, we subjected to comparative infection and sedimentation analysis cell culture-produced (HCVcc, genotype 2a) wild type virus, a panel of alanine single-site mutants and a HVR1-deletion variant. Initially, we analyzed the effects of these mutations on E2-heparan sulfate (HS) interactions. The positive milieu of the HVR1, formulated by its basic amino acids (key residues the conserved H³⁸⁶ and R⁴⁰⁸), and the two highly conserved basic residues H⁴⁸⁸ and R⁶⁴⁸ contributed to E2-HS interactions. Mutations in these residues did not alter the HCVcc-CD81 entry, but they modified the HCVcc-scavenger receptor class B type I (SR-BI) dependent entry and the neutralization by anti-E2 or patients IgG. Finally, separation by density gradients revealed that mutant viruses abolished partially or completely the infectivity of low density particles, which are believed to be associated with lipoproteins. This study shows that there exists a complex interplay between the basic amino acids located in HVR1 and other conserved E2 motifs with the HS, the SR-BI, and neutralizing antibodies and suggests that HCV-associated lipoproteins are implicated in these interactions.
authors.affiliation: Liver Unit, Hospital Clínic, Institut D'Investigacions Biomèdics August Pi i Sunyer, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Barcelona, Spain. gkoutsou@clinic.ub.es
authors.forename: George
authors.initials: G
authors.lastname: Koutsoudakis
authors.forename: Jakub
authors.initials: J
authors.lastname: Dragun
authors.forename: Sofia
authors.initials: S
authors.lastname: Pérez-Del-Pulgar
authors.forename: Mairene
authors.initials: M
authors.lastname: Coto-Llerena
authors.forename: Laura
authors.initials: L
authors.lastname: Mensa
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Crespo
authors.forename: Patricia
authors.initials: P
authors.lastname: González
authors.forename: Miquel
authors.initials: M
authors.lastname: Navasa
authors.forename: Xavier
authors.initials: X
authors.lastname: Forns
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D024361:Amino Acids, Basic / Q000737:chemistry; D057134:Antibodies, Neutralizing / Q000494:pharmacology*; D000914:Antibodies, Viral / Q000494:pharmacology; D001665:Binding Sites; D002460:Cell Line; D016174:Hepacivirus / Q000276:immunology / Q000502:physiology*; D006493:Heparin / Q000494:pharmacology; D019698:Hepatitis C, Chronic / Q000276:immunology / Q000821:virology; D054884:Host-Pathogen Interactions; D006801:Humans; D007074:Immunoglobulin G / Q000494:pharmacology; D008074:Lipoproteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D051122:Scavenger Receptors, Class B / Q000378:metabolism*; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D053586:Virus Internalization / Q000187:drug effects; D014779:Virus Replication / Q000187:drug effects
chemical_list: D024361:Amino Acids, Basic; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D007074:Immunoglobulin G; D008074:Lipoproteins; C495124:SCARB1 protein, human; D051122:Scavenger Receptors, Class B; D014759:Viral Envelope Proteins; C091015:glycoprotein E2, Hepatitis C virus; D006493:Heparin