An experimental biological model is proposed for purification of ricke
ttsiae-infected cell cultures from mycoplasma contamination using intr
avenous mouse infection and subsequent passages on Vero cell monolayer
s. Mycoplasma-free rickettsial cultures were obtained in mouse brain o
r spleen suspension within 3 hrs or 3 days, respectively, after mouse
inoculation. Ten strains of spotted fever group rickettsiae were purif
ied from mycoplasmas by this procedure.