IN VITRO SELF-ASSEMBLING PROTEIN NANOPARTICLES FOR THE DESIGN OF NEXT GENERATION CARBOHYDRATE-BASED VACCINES

Self-assembling protein nanoparticles (NPs) can be exploited as carrier for antigen delivery to increase vaccine immunogenicity by promoting a robust adaptive immune response and long-lasting protective immunity. The aim of my PhD is to explore key parameters of protein nanoparticles as carriers for saccharide-based vaccines. First, to explore the impact of NP size and shape, oligosaccharides from N. meningitidis type W capsular polysaccharide were conjugated to ring-shape or nanotubes of P. aeruginosa Hemolysin-corregulated protein 1 (Hcp1) and to spheric H.Pylori Ferritin. The corresponding glyco-NPs were compared in animal studies. The rod shape glyconanoparticles resulted less immunogenic than spheric glyconanoparticles, probably due to a different internalization efficiency. Furthermore, the increase in size for nanotubes did not improve MenW-specific immune response. Further, the potential combination of NP and adjuvant platforms was investigated by exploiting the ability of Qβ VLPs to entrap genetic material that acts as an adjuvant of the immune response to surface-exposed antigens. By using in vitro processes Qβ VLPs entrapped RNA was removed and specific, homogenous ssDNA based adjuvant – TLR 9 agonist CpG – was successfully introduced inside the Qβ cage or linked to its external surface. Qβ VLPs were subsequently conjugated with bacterial capsular polysaccharides. When entrapped in the glyco-NPs, the CpG adjuvant triggered an immune response after a single dose of vaccine that was equivalent to two doses of the corresponding CRM197 conjugate. This effect was entirely absent when the adjuvant was attached to the Qβ surface or simply co-formulated. In conclusion, protein nanoparticles that meet defined characteristics in terms of size and shape combined with adjuvants platforms can pave the way for the development of a new generation of super-potent multicomponent glycoconjugates vaccines.