ELECTROPHORESIS OF DIPHTHERIA BACILLI I. SOME RELATIONS BETWEEN THE VIRULENCE, TOXIGENICITY AND ELECTROPHORETIC MOBILITIES OF DIPHTHERIA BACILLI

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Abstract
Toxigenicity and virulence must be considered separately. The qualitative distinction between virulent and avirulent diphtheria strains rests on a spurious basis. Three hundred and eighty strains of diphtheria bacilli were used. Forty-five virulent and 5 avirulent strains were indistinguishable in behavior on 36 different substances. The authors worked on the basis of the theory that all diphtheria strains can produce toxin but that only those with a certain surface permeability excrete it. Measurements of electrophoretic potentials were made on 48-hr. veal broth cultures of toxigenic strains. Expressed in velocity the average figure was 3.4 micra per second; for avirulent strains, 12.1 micra. Strains with intermediate values were typical diphtheria bacilli, but neither toxigenic nor virulent. The inverse parallelism between electrophoretic potential and minimum lethal dose exists for some strains but not for all. The Park No. 8 strain of diphtheria bacillus, with its high toxin production, has the lowest P. D. values.