title: T cell memory to evolutionarily conserved and shared hemagglutinin epitopes of H1N1 viruses: a pilot scale study.
abstract: BACKGROUND
  The 2009 pandemic influenza was milder than expected. Based on the apparent lack of pre-existing cross-protective antibodies to the A (H1N1)pdm09 strain, it was hypothesized that pre-existing CD4+ T cellular immunity provided the crucial immunity that led to an attenuation of disease severity. We carried out a pilot scale study by conducting in silico and in vitro T cellular assays in healthy population, to evaluate the pre-existing immunity to A (H1N1)pdm09 strain.
  
  
  METHODS
  Large-scale epitope prediction analysis was done by examining the NCBI available (H1N1) HA proteins. NetMHCIIpan, an eptiope prediction tool was used to identify the putative and shared CD4+ T cell epitopes between seasonal H1N1 and A (H1N1)pdm09 strains. To identify the immunogenicity of these putative epitopes, human IFN-γ-ELISPOT assays were conducted using the peripheral blood mononuclear cells from fourteen healthy human donors. All donors were screened for the HLA-DRB1 alleles.
  
  
  RESULTS
  Epitope-specific CD4+ T cellular memory responses (IFN-γ) were generated to highly conserved HA epitopes from majority of the donors (93%). Higher magnitude of the CD4+ T cell responses was observed in the older adults. The study identified two HA2 immunodominant CD4+ T cell epitopes, of which one was found to be novel.
  
  
  CONCLUSIONS
  The current study provides a compelling evidence of HA epitope specific CD4+ T cellular memory towards A (H1N1)pdm09 strain. These well-characterized epitopes could recruit alternative immunological pathways to overcome the challenge of annual seasonal flu vaccine escape.
authors: Biology Department, York University, Toronto, Canada. dvenkata@yorku.ca.
authors: Venkata R
authors: VR
authors: Duvvuri
authors: Bhargavi
authors: B
authors: Duvvuri
authors: Veronica
authors: V
authors: Jamnik
authors: Jonathan B
authors: JB
authors: Gubbay
authors: Jianhong
authors: J
authors: Wu
authors: Gillian E
authors: GE
authors: Wu
mesh_terms: D000328:Adult; D000368:Aged; D019295:Computational Biology; D003429:Cross Reactions; D058501:Enzyme-Linked Immunospot Assay; D000939:Epitopes / Q000276:immunology*; D005260:Female; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000276:immunology*; D006801:Humans; D007156:Immunologic Memory; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007371:Interferon-gamma / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D013601:T-Lymphocytes / Q000276:immunology*; D055815:Young Adult
chemical_list: D000939:Epitopes; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007371:Interferon-gamma
references: Vaccine. 2011 Mar 3;29(11):2169-77
references: 21353149
references: Influenza Other Respir Viruses. 2010 Sep;4(5):249-58
references: 20716156
references: Nat Med. 2012 Jan 29;18(2):274-80
references: 22286307
references: Eur J Immunol. 1997 Dec;27(12):3105-14
references: 9464794
references: Vaccine. 2009 Sep 25;27(42):5740-7
references: 19660593
references: Proc Natl Acad Sci U S A. 2009 Dec 1;106(48):20365-70
references: 19918065
references: PLoS Pathog. 2011 Nov;7(11):e1002381
references: 22102819
references: Int Immunol. 1998 Feb;10(2):211-22
references: 9533449
references: Nature. 1992 Aug 27;358(6389):764-8
references: 1380674
references: J Immunol Methods. 2004 Feb 1;285(1):89-92
references: 14871537
references: AIDS. 2006 Nov 28;20(18):2263-73
references: 17117012
references: J Biol Chem. 1998 May 8;273(19):11440-7
references: 9565555
references: Immunology. 2010 Apr;129(4):496-505
references: 20002212
references: CMAJ. 2010 Feb 9;182(2):131-6
references: 19959592
references: J Immunol. 1997 Jul 1;159(1):335-43
references: 9200471
references: N Engl J Med. 2009 Nov 12;361(20):1945-52
references: 19745214
references: N Engl J Med. 2009 Jun 18;360(25):2616-25
references: 19423871
references: PLoS One. 2010 Jan 18;5(1):e8754
references: 20090904
references: J Virol. 2002 Dec;76(23):12388-93
references: 12414983
references: PLoS Comput Biol. 2008 Jul 04;4(7):e1000107
references: 18604266
references: J Immunol. 1999 Dec 15;163(12):6413-23
references: 10586031
references: Emerg Infect Dis. 2009 Dec;15(12):2004-7
references: 19961687
references: Immunol Today. 1996 Feb;17(2):80-85
references: 8808055
references: J Virol. 2010 Apr;84(7):3312-9
references: 20071564