Inactivated Pseudomonas PE(III) exotoxin fused to neutralizing epitopes of PEDV S proteins produces a specific immune response in mice

Porcine epidemic diarrhea (PED) caused by the porcine epidemic diarrhea virus (PEDV), is a severe infectious and devastating swine disease that leads to serious economic losses in the swine industry worldwide. An increased number of PED cases caused by variant PEDV have been reported in many countries since 2010. S protein is the main immunogenic protein containing some B-cell epitopes that can induce neutralizing antibodies of PEDV. In this study, the construction, expression and purification of Pseudomonas aeruginosa exotoxin A (PE) without domain III (PE Delta III) as a vector was performed for the delivery of PEDV S-A or S-B. PE(Delta III) PEDV S-A and PE(Delta III) PEDV S-B recombinant proteins were confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis. The immunogenicity of PEDV S-A and PEDV S-B subunit vaccines were evaluated in mice. The results showed that PEDV-S-B vaccine could not only induce specific humoral and Th1 type-dominant cellular immune responses, but also stimulate PEDV-specific mucosal immune responses in mice. PEDV-S-B subunit vaccine is a novel candidate mucosal vaccine against PEDV infection.