THE GROWTH OF COXIELLA BURNETII IN EMBRYONATED EGGS

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Abstract
Some of the character-istics in the growth of C. burnetii, the causative agent of Q fever, in embryonated eggs were described. The growth curve of C. burnetii in the living chick yolk sac exhibits, in terms of the complement fixation test, a lag phase and a period of exponential growth, but no sharp point of max. concn., nor a stationary phase. When chick embryos are infected with C. burnetii via the yolk sac, the infection appears to be wholly confined to the yolk sac and not to spread to other embryonic tissues. The growth rate of the chick embryo yolk sac is not greatly affected by a C. burnetii infection which is acutely lethal to the embryos. No evidence was found for the growth of C. burnetii in the tissues of dead embryos. The total number of rickettsiae in a population of living chick embryos is characterized, in the case of C. burnetii, by a rapid approach to a max., closely followed by a rapid decline. This phenomenon is important to the problem of securing max. rickettsial yield by yolk sac technic.