In summary, the collective results described in this thesis show that nanoparticulate vaccines can be delivered intradermally by coated and hollow microneedles and evoke antigen-specific immune... Show moreIn summary, the collective results described in this thesis show that nanoparticulate vaccines can be delivered intradermally by coated and hollow microneedles and evoke antigen-specific immune responses. The choice of both the nanoparticles and the microneedle(s) could have important influences on the immune responses. Microneedle arrays coated with antigen loaded and lipid bilayer fused mesoporous silica nanoparticles (MSNs) could be a promising system for convenient and fast intradermal delivery of protein antigen, although our results indicate that the system needs to be improved in order to obtain optimal immune responses. Moreover, antigen and adjuvant loaded nanoparticles can increase IgG2a (Th1) and CD8+ responses after intradermal delivery by hollow microneedles. This effect depends on the type and the physicochemical characteristics of the nanoparticles, in which smaller size and controlled release properties of antigen and adjuvant were found to correlate with the stronger effect. Finally, the combination of separate antigen loaded and adjuvant loaded nanoparticles may be as efficient as the antigen and adjuvant co-encapsulated nanoparticles for modification of the immune responses following intradermal immunization. Show less
In this thesis we describe a set of studies, performed using rodent models of malaria, aimed to identify methods to improve vaccines consisting of live attenuated sporozoites, in particular... Show moreIn this thesis we describe a set of studies, performed using rodent models of malaria, aimed to identify methods to improve vaccines consisting of live attenuated sporozoites, in particular genetically attenuated parasites (GAP) vaccines. Studies in rodents and humans have shown that immunization with live-attenuated sporozoites can generate protective immunity, however induction of sterile protection in humans has required immunization with multiple vaccine doses and each dose consisting of relatively high numbers of sporozoites. Increasing the immunogenicity of whole sporozoite (wsp) vaccines can both reduce the number of sporozoites per dose and the number of vaccine doses. In the studies described in this thesis we attempted to increase GAP immunogenicity by: (i) adding adjuvants during GAP immunization; (ii) introducing genes encoding putative immunomodulatory proteins in the GAP genome to create ‘self-adjuvanting’ parasites; (iii) generating GAPs that arrest late into liver-stage development (LA-GAP) to increase antigen load and diversity during immunization; and (iv) exploring possibilities to genetically modify parasite to express vaccine antigens from different life cycle stages, in order to test the ability of parasites to induce immune responses against multiple life cycle stages and to inform the creation of a ‘multi-stage’ GAP vaccine. Show less
The work in this thesis has been focused on two subjects. The first is the assembly of alginate oligosaccharides and the generation of building blocks for the enzymatic synthesis of alginate,... Show moreThe work in this thesis has been focused on two subjects. The first is the assembly of alginate oligosaccharides and the generation of building blocks for the enzymatic synthesis of alginate, and the second is the total synthesis of large fragments of the zwitterionic SP1 polysaccharide. With these fragments, details about alginate biosynthesis can be obtained through binding studies with biosynthesis enzymes, conjugate vaccines can be generated and binding studies with major histocompatibility complex II molecules can be studied. Show less
