Multifunctional PLGA-based nanoparticles encapsulating simultaneously hydrophilic antigen and hydrophobic immunomodulator for mucosal immunization.

We describe here the development of nanoparticles made from poly(lactic-co-glycolic acid) (PLGA) able to deliver an encapsulated antigen with a Toll-Like Receptor-7 (TLR-7) agonist as immunostimulatory signal and coated with a muco-adhesive chitosan-derivate layer. The potential to stimulate an immune response of these vaccine formulations in the absence or presence of the TLR-7 agonist at the systemic and mucosal level were evaluated in mice following subcutaneous or nasal administrations. Intranasally immunized mice developed a high systemic immune response equivalent to mice injected subcutaneously. However, mucosal immune responses were only induced at local and distal sites in mucosally immunized animals. The adjuvant effect of imiquimod on the polarization of the immune response was only detected at local sites, which tends to increase safety of this vaccine delivery system.