The Endotoxin of the Cholera Vibrio

Abstract

Though it is generally agreed that the cholera vibrio contains a potent endotoxin, the nature of the toxin is by no means clear. The isolation of a toxic protein has been reported by some workers such as Galeotti, 1 Sanarelli, 2 and Hahn and Hirsch. 3 More recently the trichloracetic acid extraction method of Boivin 4 has been applied to the cholera vibrio by Checcacci, 5 Raynal, Lieou, and Feissole, 6

Damboviceanu and Barber 7 and Gallut, 8 all of whom have reported successful extraction of a toxic fraction. It has been assumed by these workers that the active material is a polysaccharide-lipid complex, though in no instance is this conclusion supported by unequivocal evidence.

In the course of a study of active immunity to infection with Vibrio cholerœ we have had occasion to isolate the toxic principle from both Inaba and Ogawa types and partially purify it. Toxic solutions of the vibrio cell substance have been prepared in the following ways: (a) The cells are readily disintegrated in 4-5 hours by high speed grinding with sand, and the cellular debris is spun off, leaving a toxic opalescent supernate. (b) The cells may be dissolved in 6 M urea to give a similar toxic solution, (c) The cells may be digested with pepsin 3-5 days without inactivation of the toxicity, and the insoluble material removed by centrifugation to leave a toxic supernate. (d) The intact cells may be extracted in the cold with M/2 trichloracetic acid, all the toxicity going into solution, (e) Lyophilized cells may be extracted with methyl alcohol, ethyl alcohol, chloroform, or ethyl ether in a Soxhlet apparatus to give toxic extracts. Attempts to extract the toxicity from the intact cells with glycols have not been successful.