Highly Immunogenic Trimethyl Chitosan-based Delivery System for Intranasal Lipopeptide Vaccines against Group A Streptococcus

Background: Group A streptococcus (GAS) primarily colonizes the mucosal region of the upper respiratory tract, slowly leading to systemic infections. Thus, GAS-specific antibody responses are desirable at mucosal sites for early prevention against GAS colonization. Methods: Herein, we developed a potent nanoliposomes-based delivery system for mucosally active lipid core peptide (LCP)-based vaccines. Results: Trimethyl chitosan (TMC)-coated liposomes that bore a B-cell epitope derived from GAS Mprotein, stimulated potent epitope-specific mucosal and systemic antibody titres after only one boost following intranasal immunization in Swiss outbred mice. The immune responses were durable even at day 139 post-primary immunization. Conclusion: The enhanced vaccine efficacy, lowered dose, and simple and cost-effective process of producing the coated nanoliposomes should be particularly useful in developing potent peptide-based vaccines to prevent infections at the mucosal sites.