Porcine epidemic diarrhea vaccine efficacy evaluation by vaccination timing and frequencies.

Porcine epidemic diarrhea (PED) virus is a causative agent of enteric disease characterized by watery diarrhea and dehydration. Because PED has high morbidity and mortality, especially in suckling piglets, it causes a great economic loss to swine farms worldwide. Although various PED vaccines have been developed and commercialized, their efficacies are still controversial. In particular, current PED vaccination protocol (vaccination at 2 and 4 weeks before farrowing) may cause stress in pregnant sows. In this study, we compared the effects of PED vaccination timing and frequency for its efficacy by measuring the PED virus-specific antibodies. We found that vaccination at early stages of pregnancy induces similar levels of serum and colostrum antibodies with those at late stages of pregnancy. As the number of vaccinations increased, the amounts of antibody in serum and colostrum, and neutralizing activities increased. Our results provide important information for establishing a more efficient PED vaccination protocol.