Isolation and Biological Characterization of Pasteurella pestis Endotoxin.

Endotoxin containing 2.1% nitrogen, 1.6% phosphorus, 22.5% neutral hexose, 15% hexosamine, 25% esterified and amide-linked fatty acids, and 1.4% protein was isolated from Pasteurella pestis strain Alexander by slight modification of a method adapted by Tauber and Russell. The lipopolysaccharide exhibited classical endotoxic biological properties including: (i) toxicity in mice, guinea pigs, and rabbits; (ii) antigenicity in rabbits; (iii) capacity to evoke a biphasic pyrogenic response in rabbits; (iv) capacity to induce tolerance in mice to the lethal effect of endotoxin; (v) capacity to stimulate rapidly acquired resistance in mice to bacterial infection, and (vi) the capacity to produce the localized and generalized Shwartzman phenomena in rabbits. Findings obtained during the study concerning the occurrence, isolation, toxicity, and other biological properties of P. pestis endotoxin provide new evidence that endotoxin could contribute to death in plague.