Design of multi-epitope vaccine based on G2c genotype PEDV antigen and its immunogenicity and protective effect in piglets

Abstract

Porcine epidemic diarrhea virus (PEDV) remains a clinically important enteric virus, causing diarrhea, vomiting, dehydration, and high mortality in piglets. As the currently available vaccines may provide inconsistent protection against genetically heterogeneous field strains, particularly G2c variants, improved immunization strategies are still needed. In this study, a multi-epitope vaccine candidate was designed from the PEDV S, M, and N proteins using an immunoinformatics-based workflow. The final construct incorporated 8 linear B-cell epitopes, 1 CTL epitope, and 5 HTL epitopes, and was predicted to contain 6 discontinuous B-cell epitopes; porcine β-defensin-1 (PBD-1) was used as an adjuvant component and attached to the N-terminus. Computational analyses indicated favorable antigenicity, solubility, and structural stability. In vivo evaluation showed that the SMN peptide vaccine elicited PEDV-specific IgG, IgA, cytokine, and neutralizing-antibody responses. Following challenge with a virulent G2c PEDV strain, all five piglets in each peptide-vaccinated group survived, compared with three of five piglets in the commercial inactivated-vaccine group and none of the five piglets in the PBS group. These results indicate that the MEV candidate induced immune responses and improved protective outcomes in piglets, supporting its further development as a PEDV vaccine.