title: Mannan adjuvants intranasally administered inactivated influenza virus in mice rendering low doses inductive of strong serum IgG and IgA in the lung.
abstract: BACKGROUND
  H1N1 influenza viruses mutate rapidly, rendering vaccines developed in any given year relatively ineffective in subsequent years. Thus it is necessary to generate new vaccines every year, but this is time-consuming and resource-intensive. Should a highly virulent influenza strain capable of human-to-human transmission emerge, these factors will severely limit the number of people that can be effectively immunised against that strain in time to prevent a pandemic. An adjuvant and mode of administration capable of rendering ordinarily unprotective vaccine doses protective would thus be highly advantageous.
  
  
  METHODS
  The carbohydrate mannan was conjugated to whole inactivated H1N1 influenza virus at a range of ratios, and mixed with it at a range of ratios, and various doses of the resulting preparations were administered to mice via the intranasal (IN) route. Serum immunity was assessed via antigen-specific IgG ELISA and the haemagglutination-inhibition (HI) assay, and mucosal immunity was assessed via IgA ELISA of bronchio-alveolar lavages.
  
  
  RESULTS
  IN-administered inactivated H1N1 mixed with mannan induced higher serum IgG and respiratory-tract IgA than inactivated H1N1 conjugated to mannan, and HIN1 alone. Adjuvantation was mannan-dose-dependent, with 100 μg of mannan adjuvanting 1 μg of H1N1 more effectively than 10 or 50 μg of mannan. Serum samples from mice immunised with 1 μg H1N1 adjuvanted with 10 μg mannan did not inhibit agglutination of red blood cells (RBCs) at a dilution factor of 10 in the HI assay, but samples resulting from adjuvantation with 50 and 100 μg mannan inhibited agglutination at dilution factors of ≥ 40. Both serum IgG1 and IgG2a were induced by IN mannan-adjuvanted H1N1 vaccination, suggesting the induction of humoral and cellular immunity.
  
  
  CONCLUSIONS
  Mixing 100 μg of mannan with 1 μg of inactivated H1N1 adjuvanted the vaccine in mice, such that IN immunisation induced higher serum IgG and respiratory tract IgA than immunisation with virus alone. The serum from mice thus immunised inhibited H1N1-mediated RBC agglutination strongly in vitro. If mannan similarly adjuvants low doses of influenza vaccine in humans, it could potentially be used for vaccine 'dose-sparing' in the event that a vaccine shortage arises from an epidemic involving a highly virulent human-to-human transmissable influenza strain.
authors.affiliation: Bio-organic and Medicinal Chemistry Laboratory, Centre for Biomedical Research, Burnet Institute, 85 Commercial Road, Melbourne, 3004, Australia. owen.proudfoot@burnet.edu.au.
authors.forename: Owen
authors.initials: O
authors.lastname: Proudfoot
authors.affiliation: Bio-organic and Medicinal Chemistry Laboratory, Centre for Biomedical Research, Burnet Institute, 85 Commercial Road, Melbourne, 3004, Australia. sesparon@burnet.edu.au.
authors.forename: Sandra
authors.initials: S
authors.lastname: Esparon
authors.affiliation: Immunology Frontier Research Centre, 6F IFReC Research Building, 3-1 Yamada-oka, Suita, Osaka, Japan. cktang@ifrec.osaka-u.ac.jp.
authors.forename: Choon-Kit
authors.initials: CK
authors.lastname: Tang
authors.affiliation: WHO Collaborating Centre for Reference and Research on Influenza, 10 Wreckyn Street North, Melbourne, 3051, Australia. karen.laurie@influenzacentre.org.
authors.forename: Karen
authors.initials: K
authors.lastname: Laurie
authors.affiliation: WHO Collaborating Centre for Reference and Research on Influenza, 10 Wreckyn Street North, Melbourne, 3051, Australia. Ian.Barr@influenzacentre.org.
authors.forename: Ian
authors.initials: I
authors.lastname: Barr
authors.affiliation: Bio-organic and Medicinal Chemistry Laboratory, Centre for Biomedical Research, Burnet Institute, 85 Commercial Road, Melbourne, 3004, Australia. gpietersz@burnet.edu.au.|Department of Pathology, University of Melbourne, Parkville, Victoria, Australia. gpietersz@burnet.edu.au.|Department of Immunology, Monash University, Melbourne, Victoria, Australia. gpietersz@burnet.edu.au.
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Pietersz
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage* / Q000494:pharmacology; D000281:Administration, Intranasal; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000917:Antibody Formation / Q000187:drug effects; D005260:Female; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage*; D008168:Lung / Q000276:immunology* / Q000378:metabolism; D008351:Mannans / Q000008:administration & dosage* / Q000276:immunology / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D009976:Orthomyxoviridae Infections / Q000276:immunology / Q000517:prevention & control*; D014611:Vaccination / Q000379:methods
chemical_list: D000276:Adjuvants, Immunologic; D000914:Antibodies, Viral; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007252:Influenza Vaccines; D008351:Mannans