Chemical composition and biological properties of the endotoxin of Brucella abortus.

Baker, Phillip J. (University of Wisconsin, Madison), and J. B. Wilson. Chemical composition and biological properties of the endotoxin of Brucella abortus. J. Bacteriol. 90:895-902. 1965.-The ability of endotoxin to induce hypoferremia in mice was used to measure the specific activity of various endotoxin preparations of Escherichia coli and Brucella abortus and to determine the endotoxin content of several strains of B. abortus differing in virulence for guinea pigs. The endotoxin preparations from E. coli possessed greater biological activity than those from B. abortus. The same types of B. abortus endotoxin preparations, whether obtained from strains of high or low virulence, had about the same activity. Although differences in endotoxin content were noted among several strains of B. abortus of different virulence, there appeared to be no correlation between endotoxin content and virulence. Chemical analyses of B. abortus and E. coli endotoxins, based upon nitrogen, phosphorus, fatty acid ester, fatty acid amide, total fatty acids, hexose, and hexosamine content, revealed differences in chemical composition; however, these differences could not be correlated with differences in biological activity. The same types of endotoxin preparations, whether obtained from strains of B. abortus of high or low virulence, were similar in chemical composition and in biological activity. A correlation between the ability of endotoxin to induce hypoferremia and its lethal effects in mice is suggested. In general, endotoxin preparations of high hypoferremic activity had low mouse ld(50) values.