Dendritic cell-targeted nanoparticles for the delivery of DNA and protein vaccines

Dendritic cells (DCs) play a central role in shaping antigen-specific immune response. Antibody-mediated antigen targeting to DC-specific surface receptors is a promising approach to enhance vaccine efficacy. The objective of this thesis was to develop DC-targeted nanoparticulate formulations for the delivery of DNA and protein antigen using a novel strategy. The approach involved use of a two-component DC targeted delivery system for enhanced immune response. One component consisting of a recombinant bifunctional fusion protein (bfFp) was used for DC targeting, whereas, the other component made of biotinylated nanoparticles encapsulated antigen.;For DNA vaccines, two strategies were adapted. In the first strategy, bfFp functionalized biotinylated chitosan nanoparticles containing DNA-encoding for nucleocapsid (N) of severe acute respiratory syndrome coronavirus (SARS-CoV) or hemagglutinin (HA) of avian influenza virus was used for nasal delivery. Immune response studies in mice showed that intranasal administration of targeted formulation along with DC maturation stimuli (anti-CD40 mAb) enhanced magnitude of mucosal, humoral and cellular immune responses.;In the second strategy, a DNA (pDECN) vaccine encoding a fusion protein comprised of SARS CoV N antigen and anti-DEC-205 scFv was constructed. In vitro studies showed that expressed protein was able to bind with DCs. Vaccination of mice with pDECN-laoded chitosan nanoparticles induced significantly higher IgG and cytokine (IFN-γ and IL-2) response relative to SARS CoV N DNA. Coadministration of anti-CD40 antibody further improved efficacy of nanoencapsulated DNA formulations.;For the delivery of a model antigen ovalbumin (OVA), biotinylated poly(D,L-lactic- co-glycolic acid) (PLGA) nanoparticles were formulated using biotin-PEG-PLGA polymer and were decorated with bfFp. In vitro uptake studies revealed one-fold higher uptake of targeted nanoparticles compared to non-targeted NPs. In vivo studies show targeted NPs in conjunction with anti-CD40 mAb enhanced OVA-specific IgG and IgG subclass responses. Splenocytes of these mice secreted significantly higher levels of IFN-γ and IL-2, indicating Th1 response.;In conclusion, these results demonstrate that bfFp based DC targeting is a versatile approach and vaccine efficacy can be enhanced via non-invasive DC targeting. The two-component DC targeting approach can serve as a viable alternative to conventional antibody-targeted vaccines that also precludes any post-formulation modification of the antigen-loaded NPs.