Johnson, Arthur G. (The University of Michigan, Ann Arbor), and Alois Nowotny. Relationship of structure to function in bacterial O antigens. III. Biological properties of endotoxoids. J. Bacteriol. 87:809-814. 1964.-Endotoxin (somatic O antigen) was rendered much less lethal for mice and rabbits after treatment with boron trifluoride, potassium methylate, or pyridinium formate. In addition, the ability to induce the second fever peak of the biphasic febrile response characteristic of endotoxin was abolished. The capacity to prepare for the local Shwartzman reaction was also reduced after such treatments. On the other hand, stimulation of nonspecific resistance, and adjuvant action in mice was retained. The ability to elicit specific antibody was diminished after boron trifluoride treatment but only slightly retarded by the other two procedures.