Non-toxic perfringolysin O and α-toxin derivatives as potential vaccine candidates against bovine necrohaemorrhagic enteritis

PFOL491D showed no haemolytic effect on horse red blood cells and no cytotoxic effect on bovine endothelial cells. Furthermore, calves immunised with PFOL491D raised antibodies against perfringolysin O that could inhibit the perfringolysin O-associated haemolytic activity on horse red blood cells. Antisera from calves immunised with PFOL491D had a significantly higher neutralising capacity against the cytotoxic effect of C. perfringens culture supernatant to bovine endothelial cells than serum from control calves (P <0.05). Immunisation of calves with PFOL491D in combination with GST-cpa247-370 elicited antibodies against perfringolysin O and α-toxin and consequently inhibited both the perfringolysin O-associated haemolytic activity and the α-toxin-associated lecithinase activity in vitro. Additionally, the neutralising ability of these antisera on the cytotoxic effect of C. perfringens culture supernatant to bovine endothelial cells was significantly higher than that from calves immunised with PFOL491D (P <0.001). In conclusion, perfringolysin O derivative PFOL491D is an immunogenic antigen that can potentially be used to produce vaccine against bovine necrohaemorrhagic enteritis. Including α-toxin derivative GST-cpa247-370 has an additional protective effect and therefore vaccination of calves with a combination of both antigens seems even more promising.