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

Fecal virus shedding of the inoculated 5-day-old piglets is summarized in Table 3 and Fig 2A. One pig each in groups 1, 2, and 3 (10 −3 , 10 −4 and 10 −5 dilutions) were PCR positive on rectal swabs at 1 DPI with Ct values 22.98-39.97. All 4 pigs in each of groups 1-5 (10 −3 -10 −7 dilutions) were PCR positive on rectal swabs by 2 DPI and remained positive through the necropsy day 4 DPI. One pig (pig ID 9) in group 6 (10 −8 dilution) shed virus in rectal swabs starting from 3 DPI with a Ct value of 14.2 ( Table 3 ). The quantitative genomic copies/ml of PEDV RNA in rectal swabs is shown in Fig 2A. The average virus shedding in groups 1-5 (10 −3 to 10 −7 dilutions) at 2-4 DPI and virus shedding in pig ID 9 from group 6 (10 −8 dilution) at 3-4 DPI were similar, having 10 7.6 to 10 9.2 genomic copies/ml. All rectal swabs from the 3 unaffected pigs (IDs 23, 13 and 8) in group 6 (10 −8 dilution) and all 4 pigs in the negative control group were negative by PEDV PCR. Cecum contents obtained at necropsy were also tested by PEDV PCR and the results were consistent with those of the rectal swabs collected on the corresponding necropsy days (data not shown).