Effect of Porcine Epidemic Diarrhea Virus Infectious Doses on Infection Outcomes in Naïve Conventional Neonatal and Weaned Pigs

Thomas, Joseph T.; Chen, Qi; Gauger, Phillip C.; Giménez-Lirola, Luis G.; Sinha, Avanti; Harmon, Karen M.; Madson, Darin M.; Burrough, Eric R.; Magstadt, Drew R.; Salzbrenner, Holly M.; Welch, Michael W.; Yoon, Kyoung-Jin; Zimmerman, Jeffrey J.; Zhang, Jianqiang

A, B, & C) by virus-specific PCRs on rectal swabs and negative for PEDV by a virus-specific indirect fluorescent antibody assay. All pigs were administered an intramuscular injection of Excede 1 (Zoetis) per label instructions. Pigs were randomized by weight into 7 groups of 6 pigs each, one group per room, with the 6 pigs within each group housed together in one room on a solid floor. After 3 days acclimation (pigs were 24 days old), pigs in groups 1-7 were orogastrically inoculated with 10 −3 , 10 −4 , 10 −5 , 10 −6 , 10 −7 , and 10 −8 dilutions of the PEDV stock and the virus-negative cell culture media, respectively, using a size 10 French feeding tube and 60ml syringe (10ml/pig) ( Table 2 ). Pigs were evaluated for clinical signs of vomiting, diarrhea, lethargy, and body condition daily for the first week, every other day for the second week and then once weekly until 28 DPI. Rectal swabs were collected at 0-7, 10, 14, 21, and 28 DPI. Serum was collected and body weight was recorded on 0, 7, 14, 21, and 28 DPI. Three of the six pigs in each group were randomly selected for necropsy at 7 DPI with the remaining 3 pigs being necropsied at 28 DPI. Sample collections at necropsy and post-mortem diagnostics were identical to those in the neonatal pigs study. In addition, serum samples were tested for PEDV antibody using virus-specific IFA assay, virus neutralization (VN) test, and a whole virus-based enzyme linked immunosorbent assay (ELISA).