Transgenic mice expressing the diphtheria toxin receptor are sensitive to the toxin.

Whereas diphtheria and the mechanism of action of diphtheria toxin, the bacterial molecule that induces the disease, have been studied and understood for some time, the receptor that allows animal cells to bind the toxin escaped identification until recently. The receptor was identified by its ability to confer toxin-sensitivity to mouse cells, which are normally toxin-resistant. Although mice are also naturally resistant, we now demonstrate that transgenic mice expressing the diphtheria toxin receptor are as sensitive to the toxin as are humans and other toxin-sensitive animals. These transgenic mice provide a suitable model for studying modern antidotes for diphtheria.