Preparation and immunogenicity of gold glyco-nanoparticles as antipneumococcal vaccine model

Nanotechnology-based fully synthetic carbohydrate vaccines are promising alternatives to classic polysaccharide/protein conjugate vaccines. We have prepared gold glyco-nanoparticles (GNP) bearing two synthetic carbohydrate antigens related to serotypes 19F and 14 of Streptococcus pneumoniae and evaluated their immunogenicity in vivo. A tetrasaccharide fragment of serotype 14 (Tetra-14), a trisaccharide fragment of serotype 19F (Tri-19F), a T-helper peptide and D-glucose were loaded onto GNP in different ratios. Mice immunization showed that the concomitant presence of Tri-19F and Tetra-14 on the same nanoparticle critically enhanced the titers of specific IgG antibodies toward type 14 polysaccharide compared with GNP exclusively displaying Tetra-14, while no IgG antibodies against type 19F polysaccharide were elicited. This work is a step forward toward synthetic nanosystems combining synthetic carbohydrate antigens and immunogenic peptides as potential carbohydrate-based vaccines.