title: A study of Chitosan and c-di-GMP as mucosal adjuvants for intranasal influenza H5N1 vaccine.
abstract: BACKGROUND
  Highly pathogenic avian influenza A/H5N1 virus remains a potential pandemic threat, and it is essential to continue vaccine development against this subtype. A local mucosal immune response in the upper respiratory tract may stop influenza transmission. It is therefore important to develop effective intranasal pandemic influenza vaccines that induce mucosal immunity at the site of viral entry.
  
  
  OBJECTIVE
  We evaluated the humoral and cellular immune responses of two promising mucosal adjuvants (Chitosan and c-di-GMP) for intranasal influenza H5N1 vaccine in a murine model. Furthermore, we evaluated the concept of co-adjuvanting an experimental adjuvant (c-di-GMP) with chitosan.
  
  
  METHODS
  BALB/c mice were intranasally immunised with two doses of subunit NIBRG-14 (H5N1) vaccine (7·5, 1·5 or 0·3 μg haemagglutinin (HA) adjuvanted with chitosan (CSN), c-di-GMP or both adjuvants.
  
  
  RESULTS
  All adjuvant formulations improved the serum and local antibody responses, with the highest responses observed in the 7·5 μg HA CSN and c-di-GMP-adjuvanted groups. The c-di-GMP provided dose sparing with protective single radial haemolysis (SRH), and haemagglutination inhibition (HI) antibody responses found in the 0·3 μg HA group. CSN elicited a Th2 response, whereas c-di-GMP induced higher frequencies of virus-specific CD4+T cells producing one or more Th1 cytokines (IFN-γ+, IL-2+, TNF-α+). A combination of the two adjuvants demonstrated effectiveness at 7·5 μg HA and triggered a more balanced Th cytokine profile.
  
  
  CONCLUSIONS
  These data show that combining adjuvants can modulate the Th response and in combination with ongoing studies of adjuvanted intranasal vaccines will dictate the way forward for optimal mucosal influenza vaccines.
authors.affiliation: Influenza Centre, The Gade Institute, University of Bergen, Bergen, NorwayDepartment of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, Braunschweig, GermanyUniversity of Siena, Siena, ItalyVisMederi, Siena, ItalyArchimedes Development Ltd., Reading, UKDepartment of Research and Development, Haukeland University Hospital, Bergen, Norway.
authors.forename: Signe C
authors.initials: SC
authors.lastname: Svindland
authors.forename: Gabriel K
authors.initials: GK
authors.lastname: Pedersen
authors.forename: Rishi D
authors.initials: RD
authors.lastname: Pathirana
authors.forename: Geir
authors.initials: G
authors.lastname: Bredholt
authors.forename: Jane K
authors.initials: JK
authors.lastname: Nøstbakken
authors.forename: Åsne
authors.initials: Å
authors.lastname: Jul-Larsen
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Guzmán
authors.forename: Emanuele
authors.initials: E
authors.lastname: Montomoli
authors.forename: Giulia
authors.initials: G
authors.lastname: Lapini
authors.forename: Simona
authors.initials: S
authors.lastname: Piccirella
authors.forename: Inderjit
authors.initials: I
authors.lastname: Jabbal-Gill
authors.forename: Michael
authors.initials: M
authors.lastname: Hinchcliffe
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Cox
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage*; D000281:Administration, Intranasal; D032761:Animal Experimentation; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D048271:Chitosan / Q000008:administration & dosage*; D006152:Cyclic GMP / Q000008:administration & dosage / Q000031:analogs & derivatives*; D016207:Cytokines / Q000378:metabolism; D005260:Female; D006385:Hemagglutination Inhibition Tests; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D014611:Vaccination / Q000379:methods*
chemical_list: D000276:Adjuvants, Immunologic; D000914:Antibodies, Viral; D016207:Cytokines; D007252:Influenza Vaccines; C062025:bis(3',5')-cyclic diguanylic acid; D048271:Chitosan; D006152:Cyclic GMP