Title : Mapping virulence attenuation sites in PEDV genome: Implications for rational vaccine design
Abstract:
Porcine epidemic diarrhea virus (PEDV) continues to cause substantial economic losses in the global swine industry, highlighting the urgent need for rationally designed attenuated vaccines. This study systematically characterizes specific virulence-attenuating mutations in both the spike (S) and envelope (E) proteins, providing a molecular blueprint for precision vaccine development.
Utilizing reverse genetics systems, we generated a series of recombinant PEDV mutants with specific abolishments of key N-linked glycosylation sites on the S protein (rPEDV-Smut62, rPEDV-Smut381, rPEDV-Smut722). The replication kinetics of these mutants were characterized in Vero cells. Our results demonstrate that the loss of specific glycans (rPEDV-Smut62 and rPEDV-Smut722) significantly attenuated viral replication efficiency, while the replication kinetics of rPEDV-Smut381 was comparable to the wild strain. Mutations at S protein glycosylation sites Smut62 and Smut722 significantly attenuated viral pathogenicity while maintaining robust immunogenicity. In contrast, the Smut381 mutation caused attenuation but significantly compromised immunogenicity, as demonstrated by reduced neutralizing antibody titers in immunized piglets. Parallel studies revealed that the E protein contributes to virulence through dual mechanisms: triggering inflammatory responses and suppressing IFN production. Both the rPEDV-EΔaa23-aa29 and rPEDV-EN13A represent defective replication efficiency. Deletion of residues 23-29 partially attenuated the viruse by enhancing IFN responses and protected against wild virus challenge in pigs, while the EN13A point mutation markedly attenuated inflammatory and virulence.
Our findings identify S protein glycosylation sites (N62 and N722) and E protein functional domains (residues 13 and 23-29) as precise genetic targets for virulence attenuation. This study provides a strategic framework for developing next-generation PEDV vaccines through rational modulation of viral immunomodulatory elements.
