Polymer-peptide hybrids as a highly immunogenic single-dose nanovaccine.

Aim: To explore four-arm star poly(t-butyl)acrylate (P(t)BA)-peptide and linear P(t)BA-peptide conjugates as a vaccine-delivery system against Group A Streptococcus.

Materials & Methods: P(t)BA nanoparticles bearing J14 peptide epitopes were prepared via alkyne-azide 1,3-dipolar cycloaddition 'click' reaction. The conjugated products were self-assembled into small or large nanoparticles. These nanoparticle vaccine candidates were evaluated in vivo and J14-specific antibody titers were assessed.

Results & Discussion: Mice vaccinated with the nanoparticles were able to produce J14-specific IgG antibodies without the use of an external adjuvant after a single immunization. We have demonstrated for the first time that the immune responses against self-assembled P(t)BA nanoparticles are stronger for the smaller sized (~20 nm) nanoparticles compared with the larger (~500 nm) P(t)BA nanoparticles.

Conclusion: PtBA analogs have the potential to be developed as potent carrier systems for single-dose synthetic vaccines.