title: B- and T-cell memory elicited by a seasonal live attenuated reassortant influenza vaccine: assessment of local antibody avidity and virus-specific memory T-cells using trogocytosis-based method.
abstract: OBJECTIVE
  The main purpose of vaccination is to generate immunological memory providing enhanced immune responses against infectious pathogens. The standard and most commonly used assay for influenza vaccine immunogenicity evaluation is a hemagglutination inhibition assay (HAI). It is clear now that HAI assay is unable to properly assess the proven protective immunity elicited by live attenuated influenza vaccines (LAIV). New methods need to be developed for more accurate LAIV immunogenicity assessment and prediction of vaccine efficacy among target populations.
  
  
  OBJECTIVE
  Randomized placebo-controlled study of memory B- and T-cell responses to intranasal LAIV in young adults.
  
  
  METHODS
  A total of 56 healthy young adults 18-20 years old received seasonal monovalent LAIV. Mucosal memory B-cell responses were measured by IgA avidity assessment in nasal swabs. CD4 memory T cells in peripheral blood were examined by the expression of CD45RO marker and in functional test by the ability of virus-specific T cells to maintain the trogocytosis with antigen-loaded target cells.
  
  
  RESULTS
  Intranasal LAIV immunization enhances mucosal IgA avidity even without reliable increases in antibody titers. At the day 21 after vaccination, up to 40% of subjects demonstrated significant increases in both total and virus-specific CD4 memory T cells that were observed regardless of seroconversion rate measured by HAI assay.
  
  
  CONCLUSIONS
  The data suggest that immunogenicity of LAIV vaccines should be evaluated on the mucosal and cellular immunity basis. The assays applied could be used to support influenza clinical trials through preliminary screening of volunteers and subsequent measurement of anti-influenza in immunity.
authors.affiliation: Department of Virology, Institute of Experimental Medicine, Russian Academy of Medical Sciences, Saint Petersburg, Russia. gala.iem@gmail.com
authors.forename: Galina
authors.initials: G
authors.lastname: Petukhova
authors.forename: Daniil
authors.initials: D
authors.lastname: Korenkov
authors.forename: Tatiana
authors.initials: T
authors.lastname: Chirkova
authors.forename: Svetlana
authors.initials: S
authors.lastname: Donina
authors.forename: Larisa
authors.initials: L
authors.lastname: Rudenko
authors.forename: Anatoly
authors.initials: A
authors.lastname: Naykhin
mesh_terms: D000281:Administration, Intranasal; D000293:Adolescent; D000914:Antibodies, Viral / Q000276:immunology; D000915:Antibody Affinity; D017951:Antigen Presentation; D001402:B-Lymphocytes / Q000276:immunology*; D015704:CD4 Antigens / Q000032:analysis; D006805:Human Experimentation; D006801:Humans; D018928:Immunity, Mucosal; D007070:Immunoglobulin A / Q000276:immunology; D007156:Immunologic Memory; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000276:immunology*; D017493:Leukocyte Common Antigens / Q000032:analysis; D009975:Orthomyxoviridae / Q000276:immunology*; D010919:Placebos / Q000008:administration & dosage; D016865:Reassortant Viruses / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000737:chemistry / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D015704:CD4 Antigens; D007070:Immunoglobulin A; D007252:Influenza Vaccines; D010919:Placebos; D014613:Vaccines, Attenuated; D017493:Leukocyte Common Antigens; C516769:PTPRC protein, human