title: Minimal T-cell-stimulatory sequences and spectrum of HLA restriction of immunodominant CD4+ T-cell epitopes within hepatitis C virus NS3 and NS4 proteins.
abstract: The hepatitis C virus (HCV)-specific CD4+ T-cell response against nonstructural proteins is strongly associated with successful viral clearance during acute hepatitis C. To further develop these observations into peptide-based vaccines and clinical immunomonitoring tools like HLA class II tetramers, a detailed characterization of immunodominant CD4+ T-cell epitopes is required. We studied peripheral blood mononuclear cells from 20 patients with acute hepatitis C using 83 overlapping 20-mer peptides covering the NS3 helicase and NS4. Eight peptides were recognized by > or = 40% of patients, and specific CD4+ T-cell clones were obtained for seven of these and three additional, subdominant epitopes. Mapping of minimal stimulatory sequences defined epitopes of 8 to 13 amino acids in length, but optimal T-cell stimulation was observed with 10- to 15-mers. While some epitopes were presented by different HLA molecules, others were presented by only a single HLA class II molecule, which has implications for patient selection in clinical trials of peptide-based immunotherapies. In conclusion, using two different approaches we identified and characterized a set of CD4+ T-cell epitopes in the HCV NS3-NS4 region which are immunodominant in patients achieving transient or persistent viral control. This information allows the construction of a valuable panel of HCV-specific HLA class II tetramers for further study of CD4+ T-cell responses in chronic hepatitis C. The finding of immunodominant epitopes with very constrained HLA restriction has implications for patient selection in clinical trials of peptide-based immunotherapies.
authors.affiliation: Department of Gastroenterology and Hepatology, University Hospital Zurich, Rämistrasse 100, 8091 Zurich, Switzerland. Tilman.Gerlach@usz.ch
authors.forename: J T
authors.initials: JT
authors.lastname: Gerlach
authors.forename: A
authors.initials: A
authors.lastname: Ulsenheimer
authors.forename: N H
authors.initials: NH
authors.lastname: Grüner
authors.forename: M-C
authors.initials: MC
authors.lastname: Jung
authors.forename: W
authors.initials: W
authors.lastname: Schraut
authors.forename: C-A
authors.initials: CA
authors.lastname: Schirren
authors.forename: M
authors.initials: M
authors.lastname: Heeg
authors.forename: S
authors.initials: S
authors.lastname: Scholz
authors.forename: K
authors.initials: K
authors.lastname: Witter
authors.forename: R
authors.initials: R
authors.lastname: Zahn
authors.forename: A
authors.initials: A
authors.lastname: Vogler
authors.forename: R
authors.initials: R
authors.lastname: Zachoval
authors.forename: G R
authors.initials: GR
authors.lastname: Pape
authors.forename: H M
authors.initials: HM
authors.lastname: Diepolder
mesh_terms: D000293:Adolescent; D000328:Adult; D000483:Alleles; D000595:Amino Acid Sequence; D017951:Antigen Presentation; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D005260:Female; D006680:HLA Antigens / Q000235:genetics / Q000502:physiology; D016174:Hepacivirus / Q000276:immunology*; D006526:Hepatitis C / Q000276:immunology; D006801:Humans; D016056:Immunodominant Epitopes; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D017361:Viral Nonstructural Proteins / Q000276:immunology*; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D006680:HLA Antigens; D016056:Immunodominant Epitopes; D017361:Viral Nonstructural Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C093542:NS4 protein, hepatitis C virus