lesion development in a new intestinal loop model indicates the involvement of a shared Clostridium perfringens virulence factor in haemorrhagic enteritis in calves.

Clostridium perfringens-associated enterotoxaemia is a fatal disease in fast growing suckler and veal calves. An intestinal loop model was developed to study the pathogenesis of the disease. Loops were injected with stationary and logarithmic C. perfringens cultures with or without, a milk protein-based commercial milk replacer for calves. Isolates tested were from cases of bovine enterotoxaemia and from calves without signs of enterotoxaemia, in addition to netB-positive and -negative isolates from poultry, a type C isolate from piglets and the human isolate JIR325. All isolates induced necrohaemorrhagic lesions in combination with milk replacer, while all control loops (i.e. medium plus milk replacer) remained histologically normal. In addition, time-course experiments were conducted using an isolate from an outbreak of bovine enterotoxaemia. Histological examination showed that the earliest lesion was congestion of the capillaries, starting within 30 min of inoculation. Haemorrhage and mucosal necrosis began at the tips of the villi 3-4 h after bacterial inoculation. These lesions are similar to those observed in natural cases of bovine enterotoxaemia. Therefore, in this model, necrohaemorrhagic lesions can be induced by C. perfringens isolates from diverse origins, suggesting that the lesions may be caused by one or more virulence factors that are shared by these isolates.