Development of a Recombinant Adeno-Associated Virus Vaccine Expressing PEDV S1 Protein: Enhanced Humoral and Cellular Immunity with Superior Neonatal Protection

The continuous spread of porcine epidemic diarrhea virus (PEDV) has highlighted the importance and necessity of developing accessible, safe, effective, and versatile vaccine platforms. While approved inactivated and attenuated vaccines have been instrumental in reducing the burdens of prevention and control and economic impacts, the induction of antibody level remains an unmet need. Here, we constructed a recombinant adeno-associated virus (rAAV-CMV-PEDV S1) expressing regions of the PEDV S1 subunit based on Adeno-associated virus serotype 2 (AAV-2) vector). We assessed its immunogenicity, durability, and protective efficacy. In mice, rAAV-CMV-PEDV S1 induced significantly more remarkable and persistent serum-specific IgG compared with the inactivated vaccine and accompanied by robust CD3 ⁺ CD8 ⁺ T cells activation within 4 weeks post-immunization. In pregnant sows, compared with commercially available inactivated and attenuated vaccines, the rAAV-CMV-PEDV S1 induced significantly higher serum and colostral IgG as well as neutralizing antibody titers, which provided piglets with abundant maternal antibodies. Crucially, challenge experiments demonstrated that rAAV-CMV-PEDV S1 conferred 80% clinical protective efficacy for piglets, accompanied by significantly reduced viral shedding loads, surpassing other vaccine groups These findings suggest that rAAV-CMV-PEDV S1 candidate could be a promising PEDV vaccine for enhancing antibody levels and could strengthen the protection of piglets against PEDV infection.