Development of a Safe and Effective mRNA Candidate Vaccine Against PEDV G2c Genotype Infection

Porcine epidemic diarrhea virus (PEDV) is a highly contagious coronavirus that causes severe diarrhea, dehydration, and high mortality in piglets, leading to significant economic losses in the swine industry. The spike (S) protein of PEDV is the primary target for neutralizing antibodies and is critical for vaccine development. In this study, the pUC57-S01 and pUC57-S02 plasmids carrying the codon-optimized truncated S gene sequence were constructed. The mRNA S01 showed higher protein expression in vitro than mRNA S02, as confirmed by Western blotting. The safety and immunogenicity of mRNA S01 were evaluated in animal experiments. The results indicated that the mRNA S01 vaccine was safe for piglets and pregnant sows. Immunogenicity was assessed by a neutralization assay, which revealed that encapsulated mRNA S01 induced high levels of neutralizing antibody titers in pigs. Challenge protection efficiency tests showed that the mRNA S01 vaccine conferred immunity to newborn piglets, protecting them from a homologous PEDV strain challenge. This study provides a foundation for the clinical application of PEDV mRNA vaccines and offers a reference for the development of novel vaccines against PEDV.