On a Specific Substance of the Cholera Vibrio.

Abstract

Differences in opinion (Levaditi, 1 Prausnitz 2 ) as to the alcohol solubility of the specific substances of the cholera Vibrio called for an experimental investigation of the subject.

While we were unable to detect such substances in extracts made with ether or hot absolute alcohol, they were present in 75 per cent alcoholic extracts of the bacilli, previously washed with saline, and extracted with ether and hot absolute alcohol. On cooling, a sediment separated from the solution which reacted with anti-cholera immune serum, up to dilutions of 1-500,000 of the antigen. This product in a 1 per cent solution gave distinct protein reactions. On hydrolysis with dilute hydrochloric acid, the solution reduced Fehling's reagent and gave a crystalline osazone. During the hydrolysis the fluid became turbid, and an insoluble product settled. The hot 75 per cent alcoholic extract was put through a Berkefeld filter, and the solution of the sediment, which appeared on cooling, was injected into rabbits. After 3 injections of 2 mg. each of the substance, precipitating and agglutinating antisera were obtained.

For further separation of the specifically reacting substance, the extraction was made first with a smaller, and then a larger volume of hot 75 per cent alcohol, and the sediment from the second extract only was used. To a 10 per cent solution, four volumes of N/10 NaOH were added, and after centrifuging, the solution was precipitated with alcohol. The precipitate was then redissolved in water, neutralized, some Na₂CO₃ added, centrifuged, and the solution precipitated with alcohol, after acidifying with acetic acid.

The precipitate obtained is a white powder, soluble in water. That the specific substance contains carbohydrates is indicated by the formation of reducing sugar upon hydrolysis.