title: Characterization of mimotopes mimicking an immunodominant conformational epitope on the hepatitis C virus NS3 helicase.
abstract: The hepatitis C virus (HCV) nonstructural 3 (NS3) protein is composed of an amino terminal protease and a carboxyl terminal RNA helicase. NS3 contains major antigenic epitopes. The antibody response to NS3 appears early in the course of infection and is focused on the helicase region. However, this response cannot be defined by short synthetic peptides indicating the recognition of conformation-dependent epitopes. In this study, we have screened a dodecapeptide library displayed on phage with anti-NS3 mouse monoclonal antibodies (mAbs) that compete with each other and human anti-HCV NS3 positive sera. Two peptides (mimotopes) were selected that appeared to mimic an immunodominant epitope since they were recognized specifically by the different anti-NS3 mAbs of the study and by human sera from HCV infected patients. Homology search between the two mimotopes and the NS3 sequence showed that one of the two peptides shared amino acid similarities with NS3 at residues 1396-1398 on a very accessible loop as visualized on the three-dimensional structure of the helicase domain whereas the other one had two amino acids similar to nearby residues 1376 and 1378. Reproduced as synthetic dodecapeptides, the two mimotopes were recognized specifically by 19 and 22, respectively, out of 49 sera from HCV infected patients. These mimotopes allowed also the detection of anti-NS3 antibodies in sera of HCV patients at the seroconversion stage. These results suggest that the two NS3 mimotopes are potential tools for the diagnosis of HCV infection.
authors.affiliation: Unité Mixte de Recherche UMR 2142 bioMérieux/CNRS, CERVI, Lyon, France. jolivet@cervi-lyon.inserm.fr
authors.forename: Colette
authors.initials: C
authors.lastname: Jolivet-Reynaud
authors.forename: Anne
authors.initials: A
authors.lastname: Adida
authors.forename: Sandrine
authors.initials: S
authors.lastname: Michel
authors.forename: Gilbert
authors.initials: G
authors.lastname: Deléage
authors.forename: Glaucia
authors.initials: G
authors.lastname: Paranhos-Baccala
authors.forename: Virginie
authors.initials: V
authors.lastname: Gonin
authors.forename: Nicole
authors.initials: N
authors.lastname: Battail-Poirot
authors.forename: Xavier
authors.initials: X
authors.lastname: Lacoux
authors.forename: Dominique
authors.initials: D
authors.lastname: Rolland
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000302:isolation & purification; D016174:Hepacivirus / Q000276:immunology*; D018937:Hepatitis C Antibodies / Q000097:blood / Q000276:immunology; D018936:Hepatitis C Antigens / Q000276:immunology; D006801:Humans; D016056:Immunodominant Epitopes; D051379:Mice; D008958:Models, Molecular; D018716:Molecular Mimicry; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry / Q000276:immunology*; D019151:Peptide Library; D020365:RNA Helicases / Q000737:chemistry* / Q000276:immunology*; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000276:immunology*; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D000911:Antibodies, Monoclonal; D018937:Hepatitis C Antibodies; D018936:Hepatitis C Antigens; D016056:Immunodominant Epitopes; D009842:Oligopeptides; D019151:Peptide Library; D020365:RNA Helicases; D017361:Viral Nonstructural Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases