Shigella dysenteriae 1-like cytotoxic enterotoxins produced by Salmonella strains.

A Salmonella enteritidis strain produced a cytotoxin in addition to heat-labile (LT) and heat-stable (ST) enterotoxins. Two strains of serotypes Salmonella kapemba and Salmonella thompson were LT and ST negative, but exhibited a cytotoxic effect. After Sephadex G-100 fractionation of the crude S. enteritidis material, some high and low molecular fractions had both cytotonic and cytotoxic activities. Of the two other salmonellae, only some high molecular fractions contained the cytotoxic substance. Neutralization experiments revealed an antigenic relationship between the cytotoxins studied and Shigella dysenteriae 1 enterotoxin. On the basis of cross neutralization and other data, it seems that cytotoxic and LT-like characters are carried by the same molecule. In S. thompson and S. kapemba the LT fails to exert a biological effect, although it is antigenically related to the LT of Escherichia coli.