Evidence for the induced nature of the change from nontoxigenicity to toxigenicity in Corynebacterium diphtheriae as a result of exposure to specific bacteriophage.

Genetic Factors in Corynebacterium Diphtheriae Conversion1

The conversion to toxigenicity of nontoxigenic Corynebacterium diphtheriae strain C4 requires the active and continued participation of a specific bacteriophage (Groman, 1953, 1955). The facts supporting this statement are: (1) lysogenization with 3 phage results in a simultaneous change to toxigenicity, and (2) reversion of toxngemnc cells to the nonlysogenic state results in a return to the n...

Evidence for the active role of bacteriophage in the conversion of nontoxigenic Corynebacterium diphtheriae to toxin production.

In a previous report (Groman, 1953a) it was concluded that toxigenic Corynebacterium diphtheriae which are recovered following exposure of a nontoxigenic strain to specific bacteriophage result from a direct conversion to toxigenicity' rather than from selection of toxigenic mutants. This conclusion was supported and strengthened by the work of Barksdale and Pappenheimer (1954) in their study o...

A modified toxigenicity test for Corynebacterium diphtheriae.

Determination of Corynebacterium diphtheriae toxigenicity by a colorimetric tissue culture assay.

Chinese hamster ovary (CHO) cell cultures in microtiter wells are sensitive to growth inhibition and killing by picogram quantities of diphtheria toxin. In the absence of biologically active toxin, the CHO cell culture produces sufficient acidic metabolites to change the phenol red pH indicator from pink to yellow within 56 h. In the presence of 10 pg of toxin per well, growth inhibition can be...

Effect of antiphage serum on the virulence of Corynebacterium diphtheriae.

There is little doubt that the toxigenicity of diphtheria cultures is associated with the lysogenic state. Blair (1924) noted that filtrates from toxigenic cultures lysed atoxic cultures of the diptheria bacillus but not the toxigenic cultures, but later investigators were able to isolate certain phages which could lyse toxigenic strains. We now know that, in general, lysogenic cultures are res...