The successful immunization of white mice against challenge with Bacterium tularense is described. The immunization procedure consisted of a single intraperitoneal injection of 0.1 ml of an ether-extracted vaccine. Four strains of B. tularense differing markedly in virulence were of equal potency when used as vaccines. The mice should be at least 40 days old when vaccinated.

Considerable immunity was apparent when the mice were subsequently challenged subcutaneously with serial 10-fold dilutions of a strain of B. tularense which possessed full virulence for mice but diminished virulence for rabbits. The protection conferred upon immunized mice was measured by the differences in LD50 titers of the control and vaccinated groups of mice.

This content is only available via PDF.
You do not currently have access to this content.