N-terminal Domain of the Spike Protein of Porcine Epidemic Diarrhea Virus as a New Candidate Molecule for a Mucosal Vaccine

Kim, Sae-Hae; Cho, Byeol-Hee; Lee, Kyung-Yeol; Jang, Yong-Suk

To induce gut mucosal immunity against pathogen infection, targeting vaccine materials to M cells is the ideal strategy, because the uptake of luminal Ags is tightly regulated in gut epithelial cells (13) . It has been suggested that targeting Ags to M cells can be enhanced by facilitating the interactions of Ag with M cell-specific molecules, such as GP2 protein, complement 5a receptor, and α (1,2)-fucose-containing carbohydrate moiety (14) (15) (16) . For example, tetanus toxoid can be targeted to M cells by complexing with an M cell-specific Ab (NKM 16-2-4), which interacts with α (1,2)-fucose-containing carbohydrate moiety, and oral administration of the complex with the mucosal adjuvant cholera toxin (CT) effectively induces tetanus toxoidspecific immune responses in the systemic and mucosal compartments (16) . In that sense, it is presumed that the NTD of the S protein of PEDV interacts with the mucosal surface based on its ability to interact specifically with 5-N-acetylneuraminic acid. In this study, we demonstrate that the partial NTD (NTD 231-501 ) of the PEDV S1 protein effectively interacts with M cells, and oral immunization of recombinant NTD 231-501 alone or together with the mucosal adjuvant CT induces Ag-specific immune responses in both the systemic and mucosal compartments. Consequently, we believe that recombinant NTD 231-501 of the PEDV S1 protein is a good candidate molecule for application in a mucosal vaccine against PEDV infection.