A Modular Self‐Assembling and Self‐Adjuvanting Multiepitope Peptide Nanoparticle Vaccine Platform to Improve the Efficacy and Immunogenicity of BCG

Abstract After more than a century since its initial development, Bacille Calmette‐Guérin (BCG) remains the only licensed vaccine against tuberculosis (TB). Subunit boosters are considered a viable strategy to enhance BCG efficacy, which often wanes in adolescence. While many studies on booster subunit vaccines have concentrated on recombinant proteins, here we developed a novel modular peptide‐based subunit vaccine platform that is flexible, cold‐chain independent and customizable to diverse circumstances and populations. Each individual peptide building block consists of a linear arrangement comprising a 15‐leucine self‐assembly inducer moiety, a Mycobacterium tuberculosis (Mtb) target epitope and an human leukocyte antigen E (HLA‐E) binding moiety, with each moiety separated by a triple lysine spacer. The building blocks, in any combination, are able to form a multiepitope nanoparticle. Six Mtb epitopes were selected to produce the self‐assembling and self‐adjuvating peptide‐based TB nano‐vaccine candidate PNx6. In vivo vaccination‐challenge experiments demonstrated that subcutaneous boost of parenteral BCG immunization with PNx6 significantly enhanced its immunogenicity and improved its protective efficacy in a murine model of TB by more than 5‐fold. This study presents evidence that purely amphiphilic peptides self‐assemble into self‐adjuvating nanoparticles with appropriate size and morphology for TB vaccination with great potential for a multitude of other diseases.