Intranasal administration is an effective mucosal vaccine delivery route for self-adjuvanting lipid core peptides targeting the group A streptococcal M protein

Abstract

Background: We investigated the lipid core peptide (LCP) system for mucosal vaccine delivery against infection with group A streptococcus (GAS)--the causative pathogen of rheumatic fever and rheumatic heart disease.

Methods: An LCP vaccine formulation containing 2 different peptide epitopes of the antiphagocytic M protein of GAS--a conformational epitope from the carboxyterminal conserved C-repeat region and an aminoterminal serotypic epitope--was intranasally administered to mice with cholera toxin B subunit or without additional adjuvant.

Results: Our data demonstrate that the LCP vaccine formulation induced the elicitation of antigen-specific systemic immunoglobulin G responses when administered with or without cholera toxin B subunit, whereas cholera toxin B subunit was required for the induction of antigen-specific mucosal immunoglobulin A responses. Immune serum samples from vaccinated mice were capable of opsonization of a homologous GAS strain, as well as opsonization of a heterologous GAS strain. Furthermore, mice were protected from GAS challenge following immunization with the LCP vaccine formulation, even in the absence of additional adjuvant.

Conclusions: These data support the potential of the LCP system in the development of a self-adjuvanting, synthetic, peptide-based mucosal GAS vaccine for the prevention of diseases caused by GAS.