Group A Streptococcal vaccine candidate: contribution of epitope to size, antigen presenting cell interaction and immunogenicity.

Objective: Utilize lipopeptide vaccine delivery system to develop a vaccine candidate against Group A Streptococcus.

Methods: Lipopeptides synthesized by solid-phase peptide synthesis-bearing carboxyl (C)-terminal and amino (N)-terminal Group A Streptococcus peptide epitopes. Nanoparticles formed were evaluated in vivo.

Results: Immune responses were induced in mice without additional adjuvant. We demonstrated for the first time that incorporation of the C-terminal epitope significantly enhanced the N-terminal epitope-specific antibody response and correlated with forming smaller nanoparticles. Antigen-presenting cells had increased uptake and maturation by smaller, more immunogenic nanoparticles. Antibodies raised by vaccination recognized isolates.

Conclusions: Demonstrated the lipopeptidic nanoparticles to induce an immune response which can be influenced by the combined effect of epitope choice and size.