Field trials evaluating the efficacy of porcine epidemic diarrhea vaccine (Harrisvaccine) in the Philippines

Porcine epidemic diarrhea (PED) is an economically devastating enteric disease characterized by vomit and diarrhea. Currentcontrol method including oral administration with PED infected intestine has been used with some degree of success. However, this management protocol provide potential risk of pathogen recontamination into the herd. Porcine Epidemic Diarrhea Vaccine, RNA (Harrisvaccines, IA, USA) is the first USDA conditionally licensed PEDV vaccine. Therefore, the study was conducted to evaluate the efficacy of the PEDV vaccine in the induction of antibody in colostrum and milk samples.

The study was conducted in two sow herds (herds A and B) located in the Philippines. In each herd, 50 sows were randomly selected based on the stratification of parity into 2 treatment groups including Control and Trial. Sows in Control group were left with no vaccination and sows in Trial group were intramuscularly injected once with PEDV vaccine (Porcine Epidemic Diarrhea Vaccine, RNA (Harrisvaccines, IA, USA) at 7 days prior to farrow. Blood samples were collected from sows at -7, 0, 7 and 14 days post farrow (DPF). Colostrum was collected within 3 hours after labor and milk samples were collected at 7, 14 and 21 DPF. Two piglets from each litter were randomly selected and ear-tagged and blood samples were collected at 14 and 21 days of age. Serum, colostrum and milk samples were assayed for the presence of PEDV specific antibody by viral neutralization (VN) assay, and ELISA IgA and IgG, specific to spike protein.

The results from 2 herds demonstrated that sows vaccinated with Porcine Epidemic Diarrhea Vaccine, RNA (Harrisvaccine, IA, USA) had significantly higher VN titer, ELISA IgA and ELISA IgG compared to the non-vaccinated sows. PED outbreak was occurred in one herd following the implementation of vaccine. The effects of the outbreak including the number of pigs weaned and pre-weaning mortality was determined. The results demonstrated that sows vaccinated with PEDV vaccine weaned significantly higher number of weaned pigs, although slight clinical diarrhea was observed. This suggested the protective efficacy provided by the vaccine.

The results show that sows intramuscularly injected with Porcine Epidemic Diarrhea Vaccine, RNA had significantly higher antibody as determined by VN titer, ELISA IgG and IgA in colostrum and milk samples compared to non-vaccinated sows. In addition, vaccinated sows weaned significantly higher number of weaned pigs following the outbreak.

Disclosure of Interest: None Declared.