The eye route has been evaluated as an efficient
vaccine delivery routes. However, in order to induce sufficient antibody production with
inactivated vaccine, testing of the safety and efficacy of the use of inactivated
antigen plus adjuvant is needed. Here, we assessed various types of adjuvants in
eyedrop as an anti-
influenza serum and mucosal Ab production-enhancer in BALB/c mice. Among the adjuvants,
poly (I:C) showed as much enhancement in
antigen-specific serum
IgG and mucosal
IgA antibody production as
cholera toxin (CT) after vaccinations with trivalent
hemagglutinin-subunits or split H1N1
vaccine antigen in mice. Vaccination with split H1N1
eyedrop vaccine antigen plus
poly(I:C) showed a similar or slightly lower efficacy in inducing antibody production than intranasal vaccination; the
eyedrop vaccine-induced immunity was enough to protect mice from lethal homologous
influenza A/California/04/09 (H1N1) virus challenge. Additionally, ocular inoculation with
poly(I:C) plus
vaccine antigen generated no signs of
inflammation within 24 hours: no increases in the
mRNA expression levels of inflammatory
cytokines nor in the infiltration of mononuclear cells to administration sites. In contrast, CT administration induced increased expression of
IL-6 cytokine mRNA and mononuclear cell infiltration in the conjunctiva within 24 hours of vaccination. Moreover, inoculated visualizing materials by
eyedrop did not contaminate the surface of the olfactory bulb in mice; meanwhile, intranasally administered materials defiled the surface of the brain. On the basis of these findings, we propose that the use of
eyedrop inactivated
influenza vaccine plus
poly(I:C) is a safe and effective mucosal
vaccine strategy for inducing protective anti-
influenza immunity.