Shreya Sharma, VIDO, University of Saskatchewan

Shreya Sharma1,2, Brittany Thivierge1, Qiang Liu, PhD1,2,3. 1. Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, Saskatchewan, Canada 2. Vaccinology and Immunotherapeutics, School of Public Health, University of Saskatchewan, Saskatoon, Saskatchewan, Canada 3. Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada

Suppressing & Conquering

Porcine epidemic diarrhea virus (PEDV) remains a critical threat to the global swine industry causing diarrhea, vomiting, and dehydration in swine and up to 100% mortality in neonatal piglets. The major circulating strains of PEDV in North America are divided into two genogroups based on the spike (S) protein, and their virulence in young pigs, G1b, "S INDEL", and G2b "non-S INDEL. The current commercial vaccines are strain specific and target only one genogroup at a time. To address this gap, we developed a bivalent subunit vaccine containing the S1 protein from G1b and G2b variants. In this study, we evaluated immunogenicity in mice to optimize antigen dosage and vaccine formulation with three Montanide adjuvants: IMS 1313 VGN, Gel 02 PR, or ISA 61 VG. The results demonstrate that all adjuvanted formulations induced robust IgG and IgA responses against S1 proteins of both genogroups. Further immunotyping of IgG subclasses (IgG1 and IgG2a) indicated that Gel 02 adjuvanted subunit vaccine induced balanced immune responses. More importantly, the ISA 61 VG group achieved the highest neutralizing antibody titers (>1:64) against both viral strains. These findings demonstrate that the bivalent subunit vaccine is a promising vaccine candidate. Based on these results the most promising adjuvant formulation will be used to evaluate the immune responses in piglets. In the future, the candidate with stronger immune responses will be used to vaccinate pregnant sows to test the protective efficacy against virus challenge in newborn piglets, offering a potential solution for controlling PEDV epidemics.