title: Infection with 2009 H1N1 influenza virus primes for immunological memory in human nose-associated lymphoid tissue, offering cross-reactive immunity to H1N1 and avian H5N1 viruses.
abstract: Influenza is a highly contagious mucosal infection in the respiratory tract. The 2009 pandemic H1N1 (pH1N1) influenza virus infection resulted in substantial morbidity and mortality in humans. Little is known on whether immunological memory develops following pH1N1 infection and whether it provides protection against other virus subtypes. An enzyme-linked immunosorbent spot assay was used to analyze hemagglutinin (HA)-specific memory B cell responses after virus antigen stimulation in nose-associated lymphoid tissues (NALT) from children and adults. Individuals with serological evidence of previous exposure to pH1N1 showed significant cross-reactive HA-specific memory B cell responses to pH1N1, seasonal H1N1 (sH1N1), and avian H5N1 (aH5N1) viruses upon pH1N1 virus stimulation. pH1N1 virus antigen elicited stronger cross-reactive memory B cell responses than sH1N1 virus. Intriguingly, aH5N1 virus also activated cross-reactive memory responses to sH1N1 and pH1N1 HAs in those who had previous pH1N1 exposure, and that correlated well with the memory response stimulated by pH1N1 virus antigen. These memory B cell responses resulted in cross-reactive neutralizing antibodies against sH1N1, 1918 H1N1, and aH5N1 viruses. The 2009 pH1N1 infection appeared to have primed human host with B cell memory in NALT that offers cross-protective mucosal immunity to not only H1N1 but also aH5N1 viruses. These findings may have important implications for future vaccination strategies against influenza. It will be important to induce and/or enhance such cross-protective mucosal memory B cells.
authors.affiliation: Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom.
authors.forename: Waleed H
authors.initials: WH
authors.lastname: Mahallawi
authors.forename: Anand V
authors.initials: AV
authors.lastname: Kasbekar
authors.forename: Maxwell S
authors.initials: MS
authors.lastname: McCormick
authors.forename: Katja
authors.initials: K
authors.lastname: Hoschler
authors.forename: Nigel
authors.initials: N
authors.lastname: Temperton
authors.forename: Samuel C
authors.initials: SC
authors.lastname: Leong
authors.forename: Helen
authors.initials: H
authors.lastname: Beer
authors.forename: Francesca
authors.initials: F
authors.lastname: Ferrara
authors.forename: Paul S
authors.initials: PS
authors.lastname: McNamara
authors.forename: Qibo
authors.initials: Q
authors.lastname: Zhang
mesh_terms: D000293:Adolescent; D000328:Adult; D001402:B-Lymphocytes / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D003429:Cross Reactions; D058501:Enzyme-Linked Immunospot Assay; D005260:Female; D006801:Humans; D007156:Immunologic Memory; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology*; D007251:Influenza, Human / Q000821:virology*; D008221:Lymphoid Tissue / Q000821:virology*; D008297:Male; D009297:Nasal Mucosa / Q000821:virology*; D055815:Young Adult