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

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

the N protein and the core neutralizing epitope (COE) could stimulate the intestines to produce local immune responses, as well as systemic immune responses, after oral immunization [13, 14] . Liu et al. constructed recombinant lactobacilli expressing the PEDV N gene or the S1 region of the S gene, and an oral inoculation showed that lactobacilli expressing the N protein could enhance the mucosal and systemic immune responses mediated by recombinant lactobacilli expressing the S1 fragment of the S protein [25] . The S protein of PEDV is a peplomer glycoprotein that is located on the surface of viral particles, and it can mediate the production of neutralizing antibodies; therefore, it is a target for vaccine research. However, the S protein is a highly glycosylated protein, and in vitro expression of recombinant S protein usually results in the loss of immunogenicity. To produce a highly effective PEDV vaccine, Meng et al. used a eukaryotic expression vector to construct a DNA vaccine expressing the PEDV S gene. This vaccine was able to effectively activate cell-mediated immunity and mediate the production of high levels of antibodies in immunized animals [28] . Liang et al. used a eukaryotic expression vector to construct a recombinant plasmid expressing the S1 region of the PEDV S gene, and they further constructed an attenuated Salmonella enterica serovar Typhimurium strain that carried a recombinant plasmid expressing the S1 region of the S gene [23] . Currently, although PEDV oral vaccines and DNA vaccines are still at the research stage and have not been applied in Chinese pig populations, these studies have broadened our understanding of PEDV vaccines, and they have provided a foundation for the future development of highly effective PEDV vaccines.