Intracellular Behavior of Brucella Variants in Chick Embryo Cells in Tissue Culture. ∗

Abstract

Summary

1) Smooth brucellae were ingested by, and multiplied within, fibroblasts in tissue culture. Non-smooth variants and strain 19 neither multiplied nor survived long intracellularly unless the cells were massively infected. Brucellae remained viable intracellularly for over 30 days despite the presence of a bactericidal concentration of streptomycin in the tissue culture medium. Extensive cytopathogenicity was not evident except with Brucella suis which caused slow destruction of the fibroblasts. Under the same conditions of culture Salmonella typhosa multiplied rapidly intracellularly and caused complete cell destruction within several days. 2) Mixed infections of fibroblasts with smooth and non-smooth brucellae showed the intracellular environment to be highly selective for the smooth type. Mutation from I to S and M to S, followed by selection of the S type, occurred in several heavily inoculated tissue cultures. The addition of anti-S antiserum or DL-$aL alanine to the tissue culture medium did not affect the smooth-selective behavior of the intracellular environment.