title: Assessment of seasonal influenza A virus-specific CD4 T-cell responses to 2009 pandemic H1N1 swine-origin influenza A virus.
abstract: Very limited evidence has been reported to show human adaptive immune responses to the 2009 pandemic H1N1 swine-origin influenza A virus (S-OIV). We studied 17 S-OIV peptides homologous to immunodominant CD4 T epitopes from hemagglutinin (HA), neuraminidase (NA), nuclear protein (NP), M1 matrix protein (MP), and PB1 of a seasonal H1N1 strain. We concluded that 15 of these 17 S-OIV peptides would induce responses of seasonal influenza virus-specific T cells. Of these, seven S-OIV sequences were identical to seasonal influenza virus sequences, while eight had at least one amino acid that was not conserved. T cells recognizing epitopes derived from these S-OIV antigens could be detected ex vivo. Most of these T cells expressed memory markers, although none of the donors had been exposed to S-OIV. Functional analysis revealed that specific amino acid differences in the sequences of these S-OIV peptides would not affect or partially affect memory T-cell responses. These findings suggest that without protective antibody responses, individuals vaccinated against seasonal influenza A may still benefit from preexisting cross-reactive memory CD4 T cells reducing their susceptibility to S-OIV infection.
authors.affiliation: Benaroya Research Institute at Virginia Mason, Seattle, WA 98101, USA.
authors.forename: Xinhui
authors.initials: X
authors.lastname: Ge
authors.forename: Venus
authors.initials: V
authors.lastname: Tan
authors.forename: Paul L
authors.initials: PL
authors.lastname: Bollyky
authors.forename: Nathan E
authors.initials: NE
authors.lastname: Standifer
authors.forename: Eddie A
authors.initials: EA
authors.lastname: James
authors.forename: William W
authors.initials: WW
authors.lastname: Kwok
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D003429:Cross Reactions; D004196:Disease Outbreaks; D000939:Epitopes; D006801:Humans; D007156:Immunologic Memory; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D013997:Time Factors
chemical_list: D000939:Epitopes