Characteristics of cytotoxin produced by Campylobacter jejuni strains

The cytotoxic activity against cultured cells of nineteen clinically isolated strains of Campylobacter jejuni was tested. These strains were found to have different profiles in cytotoxin and enterotoxin production, and the characteristics of cytotoxin were further investigated. The cytotoxin showed cell killing toxicity against CHO and HeLa cells. Vacuole formation was observed in the case of rat hepatocyte primary culture. Treatment with trypsin at 80 degrees C for 30 min inactivated the cytotoxin activity, suggesting that the toxin was protein. The toxin was produced in the culture supernatant with high specific activity per protein, followed by polymyxin and CHAPS treatment fractions in this order. This suggests that the cytotoxin was a cell-releasing toxin and that the active toxin was present as a membrane-associated form. The cytotoxin activity was separated from the enterotoxin activity by DEAE-cellulose column chromatography. The washed fraction contained enterotoxin and cytotoxin, whereas the KCl eluted fraction showed mainly cytotoxic activity.