STUDY ON THE GROWTH OF COXIELLA BURNETII IN THE L STRAIN MOUSE FIBROBLAST AND THE CHICK FIBROBLAST

Abstract

The L strain mouse fibroblast and chick fibroblast were susceptible to infection with Coxiella burnetii. Intracellular rickettsiae appeared in well-defined cytoplasmic vacuoles in the L cells. Multiplication of C. burnetii in L cells was demonstrated by a 3 log increase in egg LD50 which occurred between 2 and 72 hours incubation. No rickettsial multiplication was shown in cell-free Eagle''s medium or in L cell debris. Cell to cell spread of rickettsiae was demonstrated by the increased percentage of cells infected over a 9 day incubation period. A concentration of 0.5 mg per ml of streptomycin prevented both rickettsial penetration into the cells and medium to cell spread. C. burnetii has been maintained through numerous transfers in the L cells. Fluorescent antibody studies revealed the presence of intracytoplasmic rickettsiae 21 hours after initial invasion, whereas no intranuclear infection was observed.