STUDIES ON PLAGUE

Abstract

By means of various chemical procedures and continuous paper electrophoresis a toxin was isolated from Pasteurella pestis in a state of considerable, purity. The LD50 of the purest preparation is 1 [mu]g or 222 LD50/kg of mouse/mg of toxin N when injected intravenously and 5 [mu]g or 44 LD50/kg of mouse/mg of toxin N by the intra-peritoneal route. The toxin contains 14% N, 1.9% S and not more than 0.2% P. It is free of nucleoproteins, carbohydrate and capsular material. It behaves as a homogenous protein in the ultracentrifuge and electrophoresis cell, having a molecular weight of the order of 74,000. The puridied toxin is anti-genic and gives rise to a specific antitoxin when injected into rabbits.