The field isolate of porcine epidemic diarrhea virus (PEDV) was serially passaged in Vero cells. The cell passaged PEDV, designated KPEDV-9, was tested for its pathogenicity in the neonatal pigs, immunogenicity and safety in the pregnant sows. The result indicated that KPEDV-9 at the 93rd passage revealed reduced pathogenicity in the neonatal pigs. Pregnant sows inoculated with the attenuated virus showed increased immune responses by ELISA. In addition, delivered piglets were protected from challenge of wild type PEDV. The safety test in pregnant sows indicated that all inoculated animals farrowed the average numbers of litters of piglets. The results of this study supported that the attenuated virus derived from serial passage could be applied as vaccine for protecting suckling piglets against PEDV infection.

Vector-borne arboviruses produce mild to severe symptoms in domestic animals. Bovine ephemeral fever (BEF), Akabane, Aino, and Chuzan virus have been primarily attributed to reproductive disorders or febrile diseases in cattle, and Japanese encephalitis virus (JEV) is mainly associated with reproductive failures in swine. We investigated antibody titers from domestic swine against four bovine arboviruses (BEF, Akabane, Aino, and Chuzan virus) and from cattle against JEV in Korea. While the positive rates for Akabane and BEF were 37.4% and 15.7%, the positive incidence of Chuzan and Aino were relatively low, with positive rates of 3.04% and 0.4%, respectively, based on a virus neutralization assay. Antibody titers against more than one virus were also frequently detected in domestic swine. The incidence of JEV was 51.3% among domestic cattle. In addition, one positive case was detected in the thoracic fluids from 35 aborted calves, based on the hemagglutination inhibition test. Our results indicate that swine are susceptible hosts of bovine arboviruses without showing clinical symptoms in a natural environment. Moreover, we confirmed that JEV could be associated with reproductive failure in pregnant cattle, as were other vector-borne bovine arboviruses assessed in this study.

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