Purification and physicochemical properties of a unique Vero cell cytotoxin from Escherichia coli O157:H7.

A unique Vero cell cytotoxin has been purified to homogeneity from a strain of Escherichia coli O157:H7, using ultrafiltration with Pellicon membrane cassettes and chromatography with QAE Sephadex A-50. SDS-PAGE showed the molecular weight of the toxin to be 64,000 and the absence of subunits. Based on analytical isoelectric focusing, the toxin had pI of 5.2. This Vero cell toxin was lethal to mice and showed pathological abnormalities of the mouse colonic mucosa when administered intraperitoneally. Vero cell cytotoxicity of this toxin was not neutralizable with rabbit antiserum to Shiga toxin. Based on physicochemical and immunological properties, this toxin is different from the Shiga-like toxin previously found in this organism.