title: T-cell responses in children to internal influenza antigens, 1 year after immunization with pandemic H1N1 influenza vaccine, and response to revaccination with seasonal trivalent-inactivated influenza vaccine.
abstract: BACKGROUND
  During seasonal influenza epidemics, 5-15% of the population are affected with an illness having a nontrivial mortality, morbidity and economic burden. Inactivated influenza vaccines are routinely used to prevent influenza infection, primarily by inducing humoral immunity. In addition, trivalent-inactivated influenza vaccines have previously been shown to boost influenza-specific T-cell responses in a small percentage of adults. We investigate here the influenza-specific T-cell response, in children, 1 year after pandemic H1N1 vaccination and the ability to boost the T-cell response with trivalent-inactivated influenza immunization.
  
  
  METHODS
  Peripheral blood mononuclear cells (PBMCs) were isolated from children previously vaccinated with pandemic H1N1 vaccine, pre- and postseasonal 2010-2011 trivalent influenza vaccine (TIV) vaccination. Samples were analyzed by interferon-gamma enzyme-linked immunosorbent spot for reactogenicity toward internal influenza antigens (nucleoprotein, matrix protein 1 and nonstructural protein 1).
  
  
  RESULTS
  Basal ex vivo T-cell responses to nucleoprotein, matrix protein 1 and nonstructural protein 1 measured by interferon-gamma enzyme-linked immunosorbent spot assay were significantly higher in those children who had previously received an AS03B-adjuvanted split virion pandemic vaccine 12 months earlier rather than a nonadjuvanted whole virion vaccine. Boosting of these responses, 21 days after 2010/2011 seasonal TIV vaccination was observed regardless of age or prior pandemic vaccination regime, although boosting was greater in those groups with the lowest initial response.
  
  
  CONCLUSIONS
  We show here that children previously vaccinated with the 2009 pandemic H1N1 vaccine have measurable T-cell responses 1 year after vaccination. The magnitudes of these responses are dependent on both age of vaccine and type of pandemic H1N1 vaccine used. After 2010/2011 seasonal TIV vaccination, these T-cell responses undergo a small but significant boost.
authors.affiliation: Jenner Institute, Old Road Campus Research Building, Oxford, UK. Teresa.lambe@ndm.ox.ac.uk
authors.forename: Teresa
authors.initials: T
authors.lastname: Lambe
authors.forename: Alexandra J
authors.initials: AJ
authors.lastname: Spencer
authors.forename: Caitlin E
authors.initials: CE
authors.lastname: Mullarkey
authors.forename: Richard D
authors.initials: RD
authors.lastname: Antrobus
authors.forename: Ly-Mee
authors.initials: LM
authors.lastname: Yu
authors.forename: Philip
authors.initials: P
authors.lastname: de Whalley
authors.forename: Ben A V
authors.initials: BA
authors.lastname: Thompson
authors.forename: Claire
authors.initials: C
authors.lastname: Jones
authors.forename: Jem
authors.initials: J
authors.lastname: Chalk
authors.forename: Simon
authors.initials: S
authors.lastname: Kerridge
authors.forename: Adrian V S
authors.initials: AV
authors.lastname: Hill
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Snape
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Pollard
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Gilbert
mesh_terms: D000956:Antigens, Viral / Q000276:immunology*; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007117:Immunization, Secondary / Q000379:methods*; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D007251:Influenza, Human / Q000517:prevention & control*; D007371:Interferon-gamma / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000276:immunology*; D008297:Male; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000276:immunology
chemical_list: D000956:Antigens, Viral; D007252:Influenza Vaccines; D015164:Vaccines, Inactivated; D007371:Interferon-gamma