title: Immunogenicity of twenty peptides representing epitopes of the hepatitis B core and surface antigens by IFN-γ response in chronic and resolved HBV.
abstract: BACKGROUND
  Patients with chronic hepatitis B virus infection (CHB) usually mount a modest T cell response against HBV epitopes. In order to determine immunogenic epitopes of HBV recognized by HBV-specific T cells, previous studies focused on previously confirmed HBV epitopes and assessed the T cell response by the number of HBV-specific T cells by IFN-γ ELISPOT.
  
  
  METHODS
  We studied T cell functionality by combined in silico methods predicting HBV-specific epitopes and experimental investigations on the recognition of these epitopes. 30 chronic CHB patients and 10 patients with resolved HBV (RHB) were included in the study. We identified epitopes from the literature and by in silico analysis. These were evaluated for immunogenicity by use of synthetic peptides representing the epitopes through exposure to PBMCs from patients with CHB or RHB by IFN-γ ELISPOT. The number of IFN-γ producing cells (SFC), mean spot size (MSS) and stimulation index (SI) were recorded.
  
  
  RESULTS
  The frequency of HBV-specific T cells producing IFN-γ after stimulation with HBV epitopes was similar in CHB and RHB patients. CHB patients had a higher MSS SI than RHB patients. Patients not carrying the HLA-A2 genotype had higher SFC SI and MSS SI. Patients with HLA-A11 had higher MSS SI compared to non- HLA-A11 allele patients. HBeAg-positive patients had a lower MSS SI, and none of the HBeAg positive patients had the HLA-A11 genotype. We found 3 immunogenic epitopes not described previously.
  
  
  CONCLUSIONS
  IFN-γ ELISPOT-determined MSS is an efficient marker for T cell recognition of epitopes. This experimental measure showed the in silico analysis for epitope prediction to be a valuable tool in future studies on HLA genotypes and HBV epitopes. This way our study now points to previously unappreciated consequences of carrying the HLA-A11 allele in terms of stronger immunity to HBV.
authors.affiliation: Department of Infectious Diseases, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Skejby, Denmark. nsbj@biomed.au.dk.
authors.forename: Nanna-Sophie
authors.initials: NS
authors.lastname: Brinck-Jensen
authors.affiliation: Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 4, 8000, Aarhus C, Denmark. Vorup-jensen@biomed.au.dk.
authors.forename: Thomas
authors.initials: T
authors.lastname: Vorup-Jensen
authors.affiliation: Department of Infectious Diseases, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Skejby, Denmark. peteleut@rm.dk.
authors.forename: Peter Derek Christian
authors.initials: PD
authors.lastname: Leutscher
authors.affiliation: Department of Clinical Immunology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Skejby, Denmark. christian.erikstrup@skejby.rm.dk.
authors.forename: Christian
authors.initials: C
authors.lastname: Erikstrup
authors.affiliation: Department of Infectious Diseases, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Skejby, Denmark. joepeter@rm.dk.
authors.forename: Eskild
authors.initials: E
authors.lastname: Petersen
mesh_terms: D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D019295:Computational Biology / Q000379:methods; D058501:Enzyme-Linked Immunospot Assay; D018604:Epitope Mapping / Q000379:methods; D018984:Epitopes, T-Lymphocyte / Q000737:chemistry / Q000276:immunology*; D005260:Female; D056426:Genetic Loci; D005838:Genotype; D006680:HLA Antigens / Q000235:genetics / Q000276:immunology; D006512:Hepatitis B Core Antigens / Q000737:chemistry / Q000276:immunology*; D006514:Hepatitis B Surface Antigens / Q000737:chemistry / Q000276:immunology*; D006515:Hepatitis B virus / Q000276:immunology*; D019694:Hepatitis B, Chronic / Q000235:genetics / Q000276:immunology* / Q000378:metabolism* / Q000821:virology; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010455:Peptides / Q000737:chemistry / Q000276:immunology*
chemical_list: D018984:Epitopes, T-Lymphocyte; D006680:HLA Antigens; D006512:Hepatitis B Core Antigens; D006514:Hepatitis B Surface Antigens; D010455:Peptides; D007371:Interferon-gamma