Introduction of the bacilli by the mtravenous route or by feeding gives rise to a disease predominantly localized in the lungs. Following intracerebral infection, the bacilli first multiply rapidly in the brain tissue, and then invade other organs, producing lesions especially in the lungs. Injection of the bacilli by the intraperitoneal route is less effective than by either the intravenous or intracerebral routes; however, admixture of the bacilli with some of the components of egg yolk increases both the infectivity and the pulmonary localization.
Different strains of mice differ markedly in their susceptibility to experimental tuberculous infection; the highest susceptibility was observed among the pigmented strains (line 1 dba and C57 black). Greater resistance does not appear to depend on the ability to prevent the establishment of infection, but rather corresponds to a slower rate of progression of the infectious process.
It is possible to produce in mice tuberculosis presenting any desired degree of acuteness or chronicity by controlling certain factors which condition the initiation and the progression of the infection.