Inoculation and immunity experiments on calves with the vole strain of acid-fast bacillus

Extract

Both controls became infected, the glands of the alimentary tract showing widespread lesions and some dissemination, slight in one, a little more extensive in the other.

Of the nine vaccinated calves, five were found to have trivial tuberculous lesions in the glands adjoining the alimentary tract and four showed no macroscopic lesions, either in the glands of the alimentary tract or elsewhere.

Living bovine tubercle bacilli were not present in emulsions of mesenteric or thoracic glands of two of the four no-lesion calves and were demonstrated in the mesenteric glands but not in a bronchial gland of a third. The pooled glands of the fourth no-lesion calf caused general tuberculosis in two guinea-pigs.

Living bovine bacilli were very sparse in the thoracic glands of two of the calves with trivial lesions in the head or mesenteric glands and were not present in a bronchial gland of a calf which showed a few foci in the mesenteric glands.

Living bovine bacilli were present in lymphatic glands of one calf, but which were the glands that contained them could not be stated, as these were pooled before injection. The mesenteric glands only of the remaining calf were tested and proved infective.

No lesions were found after single vaccinations in three instances (two intravenous and one subcutaneous) and after two vaccinations in one instance, the periods between the single vaccinations and the resistance tests ranging from 2 to 6 months. There seems no advantage, therefore, in giving more than one dose of vole bacilli. The intravenous is, however, preferable to the subcutaneous method, because the former method does not produce an unsightly local lesion.