The immune response of two microbial antigens delivered intradermally, sublingually, or the combination thereof

A key consideration to produce a successful vaccine is the choice of appropriate vaccination route. Though most vaccines are administered parenterally, this route is not effective in producing a robust mucosal or cell-mediated response. Intradermal and sublingual vaccinations have been explored recently as potential needle-free immunization strategies. We explored intradermal and sublingual routes as well as the combination of the two routes in eliciting both systemic and mucosal immune responses. Mice were immunized intradermally or sublingually with dmLT, a mutant of Escherichia coli heat-labile toxin. A systemic IgG response is dominant in intradermal immunization while a mucosal IgA response is dominant in sublingual immunization. When routes were combined, a synergistic response was seen with high titers of anti-dmLT IgG and IgA. IpaB/IpaD antigens of Shigella flexneri type III secretion system, were admixed with dmLT as adjuvant and administered by each route alone or in combination. Again, the intradermal route elicited a systemic response while the sublingual route elicited a mucosal response. When combined, the routes produced a robust synergistic response to both antigens that exhibited a balanced Th1/Th2 response. These results provide a new potential needle-free immunization strategy that will benefit low income countries and increase compliance in industrial countries.