Expression and immunogenicity of recombinant porcine epidemic diarrhea virus Nsp9

Porcine epidemic diarrhea virus (PEDV) causes acute diarrhea, vomiting, dehydration, and high mortality in newborn piglets, which leads to significant economic losses. Coronavirus nonstructural protein 9 (Nsp9) is an essential RNA binding protein for coronavirus replication, which renders it a promising candidate for developing antiviral drugs and diagnosis targeting PEDV. In this study, PEDV Nsp9 protein fused with MBP protein and His-tag were expressed and purified in Escherichia coli. Furthermore, immunization of MBP-Nsp9 enhances both humoral and cellular immunity responses as compared with that of His-Nsp9 protein. Finally, the swine immunization showed that Nsp9 protein could stimulate the swine immunity system to carry out humoral immunity, and the generated antibody could inhibit the proliferation of PEDV in Vero cells. Altogether, our data provide direct evidence for the immunogenicity of PEDV Nsp9, which sheds light on the future developments of anti-PEDV drugs and vaccines for PED prevention.