The Cultivation of Rickettsia diaporica in Tissue Culture and in the Tissues of Developing Chick Embryos

Abstract

Expts. are described in which R. diaporica was cultivated in a variety of tissue cultures consisting of various chick embryonic tissues in different suspension media. Both cotton-stoppered and rubber-stoppered flasks were used. The best results were obtained with rubber-stoppered flasks containing minced yolk-sac tissue suspended in filtered human ascitic fluid, transfers being made every 8 to 12 days. By this method a series of cultures was carried through 38 consecutive transfers with the infective titre being maintained rather consistently at 1 X 10-7 to 1 X 10-8. This Rickettsia apparently cannot be cultivated in an atmosphere of pure H2. A passage strain of R. diaporica has been readily maintained in serial passage in incubating fertile eggs for over 50 transfers. Yolk-sac suspensions are consistently more infectious than other tissues of the developing chick embryo and as a rule show infective titres ranging from 1:1 billion to 1:100 billion or 10 to 1000 times greater than the highest titres obtained with tissue-culture preparations.