TYPHUS FEVER STUDIES: 1. TOXIN IN RICKETTSIA EGG CULTURES (RICKETTSIA MOOSERI)
ARMY BIOLOGICAL LABS FREDERICK MD
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It was found the Rickettsia mooseri, the causative agent of murine typhus fever, could be bred without difficulty in incubated chicken eggs. A poison was demonstrated to be in the rickettsia-containing vitelline membranes of such egg cultures, which, are used in the production of typhus fever vaccines. This poison kills mice with 24, or at most 48 hours following intraperitoneal injection. The toxin is very easily destroyed it becomes ineffective through the addition of Formalin or by heating to 60C, or after being stored for seven days. The resistance of the toxin, therefore, is no greater than that of the rickettsia. Typhus fever serums of the murine as well as of the classic typhus fever neutralize the poison. This can also sometimes be done with serums from persons who have been immunized with vaccines made from rickettsia mooseri or rickettsia prowazekki. Serum from normal humans or rabbits does not neutralize the poison. It is noteworthy that serum obtained from retroplacental blood Homoseran promptly neutralizes the poison. The demonstrated rickettsia toxin is apparently an endotoxin. The characteristic symptoms of a clinical case of typhus fever -- exanthema, disturbance of the circulatory organs and the central nervous system -- may be due to a toxin effect.