Co encapsulation of antigens and adjuvants in polymeric nanoparticles for the development of an oral vaccine formulation

PRADO, LINEIA; PASQUEVICH K; LAURA BRUNO; CORIA, LORENA; CASSATARO JULIANA

Fiocruz, Rio de Janeiro, Brasil.

Simposio; 3er Simposio de Inmunologia de America Latina; 2024

LAMIG

Oral immunization presents many advantages, nevertheless, development of an oral subunit vaccine has many challenges such us digestion at the gut. The protease inhibitor U-Omp19 from Brucella spp. was shown to be an oral vaccine adjuvant that protects co-delivered antigens from proteolysis in the gastrointestinal tract and increases antigen specific adaptive immune responses. This work aims to increase the protection of antigen by encapsulating it with U Omp19 in poly (lactic-co-glycolic) acid (PLGA) nanoparticles. Nanoparticles where synthesized using the double emulsion- solvent evaporation (DE-SE) method. Encapsulation efficiency was determined by SDS-PAGE. Characterization was done using DLS, SEM and z potential. HT-29 and Caco-2 cell lines were utilized to evaluate antigen internalization using flow-cytometry. BALB/c mice were orally immunized with the antigen and adjuvant encapsulated in nanoparticles, control groups received the non-encapsulated vaccine formulation. Specific antibody responses were determined in stool samples by ELISA. Four weeks after the last immunization adaptive immune responses were evaluated in the Peyer Patches and spleen. An increase in the internalization of the encapsulated antigen was observed compared with the non-encapsulated antigen in both cell lines. Mice immunized with nanoparticles showed a significant increase in specific IgA response, a significant increase in follicular T cell population in the spleen and of B220+ CD19+ IgA+/IgG+ antigen specific cells in the Payer Patches in comparison to non-encapsulated Ag+Adjuvant. In conclusion, we developed polymeric nanoparticles that encapsulates both the antigen and the adjuvant increasing antigen internalization, IgA specific antibodies in feces and an increase in the immune response mediated by B cells in the Payer Patches.