Design of novel chiral self-assembling peptides to explore the efficiency and mechanism of mRNA-FIPV vaccine delivery vehicles

The enhancement of conventional liposome and lipid nanoparticle (LNP) methodologies in the formulation and deployment of messenger RNA (mRNA) vaccines necessitates further refinement to augment both their effectiveness and biosafety profiles. Additionally, researching these innovative delivery carrier materials represents both a prominent focus and a significant challenge in the current scientific landscape. Here we designed new chiral self-assembling peptides as the delivery carrier for RNA vaccines to study the underlying mechanisms in the feline infectious peritonitis virus (FIPV) model system. Firstly, we successfully transcribed mature enhanced green fluorescent protein (EGFP) mRNA and feline infectious peritonitis virus nucleocapsid (FIPV N) mRNA in vitro from optimized vectors. Subsequently, we developed chiral self-assembling peptide-1 (CSP-1) and chiral self-assembling peptide-2 (CSP-2) peptides, taking into account the physical and chemical characteristics of nucleic acid molecules as well as the principles of self-assembling peptides, with the aim of improving the delivery efficiency of mRNA molecule complexes. We determined the optimal coating ratio between CSP and mRNA by electrophoretic mobility shift assay. We found that the peptides and mRNA complexes can protect the mRNA from RNase A enzyme and efficiently deliver mRNA into cells for target antigen proteins expression. Animal experiments confirmed that CSP-1/mRNA complex can effectively trigger immune response mechanisms involving IFN-γ and T cell activation. It can also stimulate CD4