[The effect of serial passage of Coxiella burnetii in chick embryos on pathogen phase variability]

Coxiella burnetii has been investigated in different egg passages (EP-17, 163). Coxiella in EP 163 was completely eliminated from the suspension during the purification but not that in EP 17. It means that the coxiella of the two EP with a seroreaction of phase II are different, and phase II positivity of EP 17 can't be the result of presence of two populations in the suspension or of one mutation during the multiplication in yolk sacs but of a change on the surface of C. burnetii.