title: Memory T cells specific for HBV enumerated by a peptide-based cultured enzyme-linked immunospot assay in healthy HBV-vaccinated subjects.
abstract: Hepatitis B vaccine is the most effective strategy to control hepatitis B virus (HBV) infection and disease. It is considered that an anti-HBs (antibodies against HBV surface antigen) titer >10 mIU/ml, measured shortly after a complete vaccination schedule, provides protection against infection. Approximately 4-10% of healthy individuals fail to respond to 3-dose vaccination. Long-term HBV-specific memory T-cell response has not been fully investigated, mainly due to the lack of a suitable assay. We quantified HBV-specific expandable memory T cells by using a cultured IFN-γ enzyme-linked immunospot (ELISPOT) assay. Cultured ELISPOT response to an overlapping peptide pool representing the complete L (large) HBV envelope polypeptide was evaluated in 41 healthy subjects vaccinated 15-20 y earlier and 5 unvaccinated. Plasma samples were tested for anti-HBs. Vaccinated subjects had significantly higher HBV-specific T-cellular response than unvaccinated (p = 0.0002). HBV-specific T-cell response was mainly mediated by CD4+T cells. No concordance was found between cultured ELISPOT and anti-HBs data in vaccinated subjects. Thirty-one (76%) vaccinated subjects were responders (anti-HBs >10 mIU/ml). Nineteen (46%) vaccinated subjects were considered to be responders in cultured ELISPOT. Twenty-two (54%) vaccinated subjects were considered non-responders in cultured ELISPOT; 5 of them (23%) were also humoral non-responders. About 12% of healthy HBV-vaccinated subjects are both humoral and cellular non-responders. Although the prognostic value of this assay has not been established in terms of predictability for susceptibility to de-novo HBV infection, ELISPOT data suggest that these subjects may be at risk for HBV infection and disease, especially health care workers.
authors.affiliation: a Department of Clinical, Surgical, Diagnostic and Pediatric Sciences , University of Pavia , Pavia , Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Cassaniti
authors.affiliation: b Molecular Virology Unit, Microbiology and Virology Department , Fondazione IRCCS Policlinico San Matteo , Pavia , Italy.
authors.forename: Sandra A
authors.initials: SA
authors.lastname: Calarota
authors.affiliation: b Molecular Virology Unit, Microbiology and Virology Department , Fondazione IRCCS Policlinico San Matteo , Pavia , Italy.
authors.forename: Kodjo M G
authors.initials: KM
authors.lastname: Adzasehoun
authors.affiliation: b Molecular Virology Unit, Microbiology and Virology Department , Fondazione IRCCS Policlinico San Matteo , Pavia , Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Chiesa
authors.affiliation: b Molecular Virology Unit, Microbiology and Virology Department , Fondazione IRCCS Policlinico San Matteo , Pavia , Italy.|c Experimental Research Laboratories , Biotechnology Area, Fondazione IRCCS Policlinico San Matteo , Pavia , Italy.
authors.forename: Giuditta
authors.initials: G
authors.lastname: Comolli
authors.affiliation: b Molecular Virology Unit, Microbiology and Virology Department , Fondazione IRCCS Policlinico San Matteo , Pavia , Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Parea
authors.affiliation: a Department of Clinical, Surgical, Diagnostic and Pediatric Sciences , University of Pavia , Pavia , Italy.|b Molecular Virology Unit, Microbiology and Virology Department , Fondazione IRCCS Policlinico San Matteo , Pavia , Italy.
authors.forename: Fausto
authors.initials: F
authors.lastname: Baldanti
mesh_terms: D000328:Adult; D058501:Enzyme-Linked Immunospot Assay / Q000379:methods*; D005260:Female; D064368:Healthy Volunteers; D006509:Hepatitis B / Q000517:prevention & control; D017325:Hepatitis B Vaccines / Q000008:administration & dosage / Q000276:immunology; D006515:Hepatitis B virus / Q000276:immunology*; D006801:Humans; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000378:metabolism; D018655:Lymphocyte Count / Q000379:methods*; D008297:Male; D016176:T-Lymphocyte Subsets / Q000276:immunology*
chemical_list: D017325:Hepatitis B Vaccines; D007371:Interferon-gamma
keywords: anti-HBsAg specific antibodies; cultured ELISPOT; hepatitis B vaccine; hepatitis B virus; memory T cells