Location: Virus and Prion Research
Project Number: 5030-32000-230-080-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Jan 15, 2024
End Date: Jan 14, 2026
Objective:
The specific objectives of this proposal are: I) Validate and invalidate immune antagonists and investigate the antagonism hierarchy of Porcine Epidemic Diarrhea Virus (PEDV). II) Identify an optimal combination of immune antagonists that profoundly attenuates PEDV upon inactivation but allow it to induce a strong antibody response. III) Evaluate the candidacy (antibody response, protective lactogenic immunity, genetic stability, etc.) of PEDV mutants as live-attenuated vaccines in porcine models.
Approach:
For Aim 1 a series of recombinant PEDV mutants (mutations in anti-host response genes) will be plaque-purified and validated with full-genome sequencing. Virus phenotypes (growth curves, mRNA synthesis, protein expression, etc.) in Vero cells will be characterized. Based on these assays, the hierarchical order of the single gene mutants' immune antagonist activity will be determined. To enhance safety, PEDV double-mutants that carry combinations of nuclease mutations will be evaluated for viral growth and immune phenotypes in vitro as just described.
For Aim 2, double mutant viruses selected from Aim 1 will be evaluated in vivo. Porcine models will be used to evaluate the pathogenicity, immunogenicity, and safety of PEDV mutant viruses. Model 1: Neonatal piglets, which are highly sensitive to PEDV-induced diarrhea, will be used to evaluate the pathogenicity of PEDV mutants. Model 2): Weaned pigs, which are more resistant to severe PEDV-induced diarrhea, will be used as surrogates for gilts and sows to evaluate the mucosal immune response, and the capacity of PEDV mutant viruses to induce protective immunity. Model 3): Pregnant gilts will be used in a pilot study to determine if oral vaccination during gestation is sufficient to elicit colostral immunity that protects their neonatal piglets from mortality during PEDV infection.
