Effect of a soluble pseudo-receptor on verotoxin 2-induced toxicity.

To neutralize the toxicity of verotoxin (VT) produced by Escherichia coli type O-157, a soluble pseudo-receptor (Lyso Gb3) was synthesized with the deacylated form of the natural receptor, globotrisylceramide (Galalpha 1-4Galbeta1-4-glucosylceramide; Gb3). In this study, we evaluated the characteristics and pharmacological effects of Lyso Gb3, using VT2. It was confirmed that Lyso Gb3 specifically recognized VT2. Lyso Gb3 itself had little influence on the in-vitro growth of Vero cells, but markedly augmented VT2-induced cytotoxicity. In addition, the VT2-induced killing of mice was not decreased, but was, rather, increased by Lyso Gb3. These results indicate that the soluble pseudo-receptor Lyso Gb3 recognized VT2. However, it did not reduce, but, rather, enhanced, VT2-induced toxicity in the presence of the natural receptor, although Lyso Gb3 alone had no toxicity.