Epidemiology and vaccine of porcine epidemic diarrhea virus in China: a mini-review

SUN, Dongbo; WANG, Xinyu; WEI, Shan; CHEN, Jianfei; FENG, Li

Conventional vaccine: Wang et al. reported that a tissueinactivated PEDV vaccine was prepared using PEDV strain S [38] . Through Houhai acupoint immunization, the active immunization protection rate of the prepared PEDV tissueinactivated vaccine in three-day-old piglets was 77.28%, and the passive immunization protection rate was 97.06%, while the immunization protection period was six months. Improving the tissue-inactivated PEDV vaccine involves a complicated preparation process, high production cost, high time requirement and quality control problems. Ma et al. adapted PEDV strain CV777 to Vero cells and successfully performed continuous passages by adding trypsin to the culture medium [27] . An inactivated PEDV vaccine was prepared using the cultures of 28th passage viruses [27] . Through Houhai acupoint immunization, the active immunization protection rate in piglets was 85.19%, and the passive immunization protection rate was 85.0%. However, inactivated PEDV vaccines still exhibited some limitations, including the need for high immunization doses and multiple booster immunizations, as well as short immunity durations. Tong et al. reported that an attenuated PEDV vaccine strain (a 90th generation cloned virus strain) was successfully prepared by serial passage in vitro [36] . Through Houhai acupoint immunization, the attenuated PEDV vaccine had a 95.52% active immunization protection rate and a 96.2% passive immunization protection rate in three-to six-day-old piglets.