Evaluation of the effect of two adjuvants coadministered with nasal recombinant hemagglutinin influenza vaccine on immune cells in mice.

Vaccination is the most potent and cost-effective way to combat the threat of influenza outbreaks. Strategies to enhance influenza vaccine immunogenicity include the use of high antigen dose vaccines and the inclusion of an appropriate adjuvant. The benefits of adjuvants include enhanced immunogenicity, antigen-sparing, and greater duration of protection. However, adjuvants can increase vaccine reactogenicity and may adversely impact vaccine safety; hence, both risks and benefits need to be carefully considered when adding adjuvants to a vaccine. In this study, we examined the efficacy of aluminum hydroxide (alum), a representative Th2-type adjuvant, and CpG oligodeoxynucleotide (CpG ODN), a Toll-like receptor 9 agonist, as adjuvants for the influenza vaccine in mice. BALB/c mice were intranasally administered recombinant hemagglutinin (HA) H1N1 vaccine formulated with or without alum and/or CpG ODN. The double adjuvanted vaccine was effective for inducing B cells and NK cells in the lymph node, and B cells in the lung after infection. Additionally, double adjuvants were observed to be effective for antibody production and immune cell activation in various organs, in addition to suppressing side effects. Intranasally-administered double adjuvanted vaccines may serve as an effective means to prevent infection and to reduce side effects of the influenza vaccine.