Generation and protective efficacy of a cold-adapted attenuated genotype 2b porcine epidemic diarrhea virus

Won, Hokeun; Lee, Dong-Uk; Jang, Guehwan; Noh, Yun-Hee; Lee, Seung-Chul; Choi, Hwan-Won; Yoon, In-Joong; Yoo, Han Sang; Lee, Changhee

A PEDV Aram-P5 stock with a known cell culture infectious titer of 10 5.0 TCID 50 /mL was serially diluted 10-fold with cell culture medium, giving rise to theoretical infectious titers of 10 3 to 10 −1 TCID 50 /mL for the 10 −2 to 10 −6 dilutions, respectively, which were later used to determine the outcomes of infection in 5-day-old piglets ( Table 1) . Each group (groups 1-5) of five piglets was challenged orally with the 10-fold serially diluted (10 −2 -10 −6 ) Aram-P5 virus, while control animals in group 6 were fed cell culture medium. All five piglets in the groups 1 to 3 (inoculated with virus dilutions 10 −2 to 10 −4 ) and three piglets in group 4 (inoculated with virus dilution 10 −5 ) developed moderate to watery diarrhea (scores 2-3) by 3 DPI and it lasted through the study period ( Table 1) . By 5 DPI, 100% pigs of group 1, 60% (3/5) pigs of groups 2 and 3, and 20% (1/5) pigs of group 4 died from PED-related clinical signs. In contrast, all five pigs in groups 5 (inoculated with virus dilution of 10 −6 ) and the negative control group remained active and clinically unaffected throughout the 5-day experimental period. The PDD 50 and LD 50 of the Aram virus were determined as 5.2 log 10 PDD 50 /mL and 4.0 log 10 LD 50 / mL, indirectly corresponding to theoretical cell culture infectious titers of 10 0.2 TCID 50 /mL and 10 1 TCID 50 /mL, respectively.