Efficacy of inactivated variant porcine epidemic diarrhea virus vaccines in growing pigs

Lee, Seung Heon; Yang, Dong-Kun; Kim, Ha-Hyun; Cho, In-Soo

Twenty growing pigs (6 weeks old) were purchased from a PEDV-free pig farm and housed at the laboratory animal facility of the Animal and Plant Quarantine Agency in accordance with Institutional Animal Care and Use Committee protocols (ethics approval number: 2017-573). Before the start of the experiment, all pigs were verified as serologically negative for PEDV. After 1 week of acclimatization, pigs were randomly divided into four vaccination groups of four pigs each and comingled in two separate rooms for the duration of the experiment. Pigs in the vaccination groups were immunized twice intramuscularly at a 2-week interval with 2 mL of the experimental PEDV vaccine. The four remaining contact pigs were not vaccinated and were used as controls. At 42 days after the first vaccination, all pigs were challenged orally with PEDV QIAP1401-11p (1 mL 10 4.0 TCID50/mL). Clinical signs of PEDV infection were observed daily for 15 days, and the clinical score was determined based on diarrhea severity: 0, no clinical signs, healthy; 1, moderate diarrhea; and 2, severe diarrhea, vomiting and dehydration. Fecal samples were collected daily for the duration of the challenge to monitor viral shedding in feces. Serum samples for immunoserological analysis were collected at 0, 14, and 28 days post-vaccination (dpv) and 15 days post-challenge (dpc), i.e., 43 dpv.