A non-toxic recombinant protein rSUMO-CPBm4 as a potential vaccine candidate against Clostridium perfringens type C beta enterotoxemia

Beta toxin (CPB) is a lethal toxin and plays a key role in enterotoxemia of ruminants caused by Clostridium perfringens type C strain.The existing vaccines based on crude CPB need time-consuming detoxification and difficult quality control steps.In this study, we synthesized the rCPB m4 of C. perfringens type C strain and small ubiquitin-like modifier (SUMO)-tag CPB m4 (rSUMO-CPB m4 ) by introducing four amino acid substitutions: R212E, Y266A, L268G, and W275A.Compared with rCPB m4 , rSUMO-CPB m4 was expressed with higher solubility in Escherichia coli BL21 (DE3).Neither rCPB m4 nor rSUMO-CPB m4 was lethal to mice.Although rCPB m4 and rSUMO-CPB m4 were reactogenic with polyclonal antibodies against crude CPB, rabbits vaccinated with rSUMO-CPB m4 developed significant levels of toxin-neutralizing antibody (TNA) titers that conferred protection against crude toxin challenge.These data suggest that genetically detoxified rSUMO-CPB m4 is a promising subunit vaccine candidate for C. perfringens type C beta enterotoxemia.