Oral efficacy of Vero cell attenuated porcine epidemic diarrhea virus DR13 strain.

A Vero cell attenuated porcine epidemic diarrhea virus (PEDV) strain, DR13, was distinguished from wild-type PEDV using restriction enzyme fragment length polymorphism (RFLP). Cell attenuated DR13 was orally or intramuscularly (IM) administered to late-term pregnant sows, and mortality resulting from the highly virulent PEDV challenge was investigated in passively immunized suckling piglets of the two different groups. The mortality rate of the oral group (13%) was lower than that of the IM group (60%). In particular, the concentration of IgA against PEDV was higher in piglets of sows in the oral group, compared to the IM group. The attenuated DR13 virus remained safe, even after three backpassages in piglets. The findings of this study support the theory that the Vero cell attenuated DR13 virus may be applied as an oral vaccine for inducing specific immunity in late-term pregnant sows with a high margin of protection against PEDV infection.