A Novel Inactivated Vaccine Based on an Emerging PEDV GIIc Variant Provides Broad Cross-Protection Against Heterologous Strains

Porcine epidemic diarrhea virus (PEDV), particularly the emerging GII genotype, poses a severe threat to the global swine industry. Current vaccines based on classical strains often provide limited cross-protection against these heterogeneous variants. In this study, a novel PEDV GIIc strain, designated as PEDV-HeN2024, was successfully isolated and identified through cell culture, immunofluorescence assay (IFA), genetic sequencing, and phylogenetic analysis. Animal challenge studies demonstrated that this isolation exhibited high pathogenicity, causing severe diarrhea in both 3-5-day-old piglets. Furthermore, an inactivated vaccine was developed by emulsifying the purified virus with ISA 201 VG adjuvant (1:1, v/v). In contrast to the commercial vaccine, the PEDV-HeN2024 inactivated vaccine induced significantly higher titers of neutralizing antibodies and virus-specific total immunoglobulins in immunized animals. Crucially, these antibodies elicited broad cross-neutralizing activity against homologous GIIc, as well as heterologous GIIa and GIIb strains in vitro and in vivo. Our findings indicate that the inactivated vaccine candidate developed from the emerging PEDV-GIIc variant is a promising broad-spectrum vaccine for controlling the prevalent PEDV strains.