title: Heterosubtypic T-cell responses against avian influenza H5 haemagglutinin are frequently detected in individuals vaccinated against or previously infected with human subtypes of influenza.
abstract: BACKGROUND
  Cellula r immune responses play a critical role in providing help for the production of neutralizing antibodies to influenza virus, as well as producing anti-viral cytokines and killing infected cells in the lung. Heterosubtypic T-cell responses between different subtypes of influenza have been shown to exist in humans and to provide protection against morbidity and mortality associated with H5N1 infection in animal challenge models. Therefore, existing T-cell responses induced by natural infection or vaccination in humans may provide some degree of protection from infection with H5N1 strains, or may attenuate the severity of disease.
  
  
  OBJECTIVE
  To investigate heterosubtypic T-cell responses to avian influenza in humans.
  
  
  METHODS
  T-cell responses to an overlapping set of H5 HA peptides and inactivated viruses (H1N1, H3N2 and H5N1) were assessed using IFN-gamma and IL-2 enzyme-linked immunospot (ELISpot) assays in a cohort of adults either vaccinated against seasonal influenza in the last 3 years (n = 20) or previously infected (n = 40).
  
  
  RESULTS
  T-cell responses to all three subtypes of virus were found in both infected and vaccinated individuals by IFN-gamma and IL-2 ELISpot assays. Approximately half of the participants from each group had a positive T-cell response to the H5 HA peptides in the IFN-gamma or IL-2 ELISpot assay.
  
  
  CONCLUSIONS
  Heterosubtypic T-cell responses to H5 HA occur quite frequently in vaccinated and infected individuals. Further investigation of these responses and what role they may play upon challenge or vaccination against H5N1 may assist in vaccine design for avian influenza.
authors.affiliation: Burnet Institute, Prahran, Vic, Australia.
authors.forename: Kylie
authors.initials: K
authors.lastname: Goy
authors.forename: Sally
authors.initials: S
authors.lastname: Von Bibra
authors.forename: Jenny
authors.initials: J
authors.lastname: Lewis
authors.forename: Karen
authors.initials: K
authors.lastname: Laurie
authors.forename: Ian
authors.initials: I
authors.lastname: Barr
authors.forename: David
authors.initials: D
authors.lastname: Anderson
authors.forename: Margaret
authors.initials: M
authors.lastname: Hellard
authors.forename: Rosemary
authors.initials: R
authors.lastname: Ffrench
mesh_terms: D000328:Adult; D000956:Antigens, Viral / Q000276:immunology*; D005260:Female; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000276:immunology*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology; D007252:Influenza Vaccines / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology*; D007371:Interferon-gamma / Q000378:metabolism; D007376:Interleukin-2 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D013601:T-Lymphocytes / Q000276:immunology*; D055815:Young Adult
chemical_list: D000956:Antigens, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines; D007376:Interleukin-2; C109963:hemagglutinin, avian influenza A virus; D007371:Interferon-gamma