The mucosal and systemic immune responses elicited by a chitosan‐adjuvanted intranasal influenza H5N1 vaccine

Abstract

Please cite this paper as: Svindland et al. The mucosal and systemic immune responses elicited by a chitosan‐adjuvanted intranasal influenza H5N1 vaccine. Influenza and Other Respiratory Viruses DOI:10.1111/j.1750‐2659.2011.00271.x. Background Development of influenza vaccines that induce mucosal immunity has been highlighted by the World Health Organisation as a priority (Vaccine 2005;23:1529). Dose‐sparing strategies and an efficient mass‐vaccination regime will be paramount to reduce the morbidity and mortality of a future H5N1 pandemic. Objectives This study has investigated the immune response and the dose‐sparing potential of a chitosan‐adjuvanted intranasal H5N1 (RG‐14) subunit (SU) vaccine in a mouse model. Methods Groups of mice were intranasally immunised once or twice with a chitosan (5 mg/ml)‐adjuvanted SU vaccine [7·5, 15 or 30 μg haemagglutinin (HA)] or with a non‐adjuvanted SU vaccine (30 μg HA). For comparison, another group of mice were intranasally immunised with a whole H5N1 (RG‐14) virus (WV) vaccine (15 μg HA), and the control group consisted of unimmunised mice. Results The chitosan‐adjuvanted SU vaccine induced an immune response superior to that of the non‐adjuvanted SU vaccine. Compared with the non‐adjuvanted SU group, the chitosan‐adjuvanted SU vaccine elicited higher numbers of influenza‐specific antibody‐secreting cells (ASCs), higher concentrations of local and systemic antibodies and correspondingly an improved haemagglutination inhibition (HI) and single radial haemolysis (SRH) response against both the homologous vaccine strain and drifted H5 strains. We measured a mixed T‐helper 1/T‐helper 2 cytokine response in the chitosan‐adjuvanted SU groups, and these groups had an increased percentage of virus‐specific CD4+ T cells producing two Thelper 1 (Th1) cytokines simultaneously compared with the non‐adjuvanted SU group. Overall, the WV vaccine induced higher antibody concentrations in sera and an HI and SRH response similar to that of the chitosan‐adjuvanted SU vaccine. Furthermore, the WV vaccine formulation showed a stronger bias towards a T‐helper 1 profile than the SU vaccine and elicited the highest frequencies of CD4+ Th1 cells simultaneously secreting three different cytokines (INFγ+, IL2+ and INFα+). As expected, two immunisations gave a better immune response than one in all groups. The control group had very low or not detectable results in the performed immunoassays. Conclusion The cross‐clade serum reactivity, improved B‐ and T‐cell responses and dose‐sparing potential of chitosan show that a chitosan‐adjuvanted intranasal influenza vaccine is a promising candidate vaccine for further preclinical development.

Persistence and avidity maturation of antibodies to A(H1N1)pdm09 in healthcare workers following repeated annual vaccinations

“…SRH was performed according to previously described procedures using whole inactivated H1N1-virus [19] based on a standardised method [20]. A haemolytic zone with area ≤4 mm 2 was considered seronegative, areas of 4-24 mm 2 were considered positive but not protective, and ≥25 mm 2 was considered as protective according to the CHMP guidelines [21].…”

A study of Chitosan and c‐di‐GMP as mucosal adjuvants for intranasal influenza H5N1 vaccine

“…In vitro studies have also shown that chitosan may promote paracellular transport through a transient opening of intercellular tight junctions 22 . CSN is a safe mucosal adjuvant, 23 which augmented the immune response to intranasally administered influenza vaccine 24 . The bacterial second messenger (3′, 5′)‐cyclic dimeric guanylic acid (c‐di‐GMP) has been identified in bacteria but not in higher eukaryotes (reviewed in Ref.…”

Antigen Delivery Systems I

“…Alkaline deacetylation of chitin yields chitosan, a negatively charged polymer that has been extensively studied as a candidate mucosal adjuvant for both intranasal (i.n.) (Svindland et al, 2012;Kobayashi et al, 2013) and oral vaccines ( Barhate et al, 2013). The main mechanism by which chitosan enhances vaccine residence time is through electrostatic interactions to negatively charged cell surface moieties and mucus.…”