PROTECTION OF CATTLE FROM BOVINE TUBERCULOSIS BY VACCINATION WITH BCGBY THE RESPIRATORY OR SUBCUTANEOUS ROUTE, BUT NOT BY VACCINATION WITHKILLED MYCOBACTERIUM-VACCAE

Groups of cable were vaccinated either with BCG Pasteur by the intratr acheal or subcutaneous route or with killed Mycobacterium vaccae by th e intradermal route and challenged intratracheally 54 days later with Mycobacterium bovis. Vaccination with BCG resulted in fewer animals de veloping tuberculous lesions and in a reduction in the number of lesio ns in the diseased animals compared with the unvaccinated group and th e group vaccinated with M vaccae. None of the nine animals vaccinated intratracheally with BCG developed any tuberculous lung lesions after challenge with M bovis, but two of the nine animals from each of the g roups dosed subcutaneously with low and medium doses of sec developed lung lesions. There was little difference in protection against the M bovis challenge between the animals receiving the low dose (10(3) colo ny forming units, cfu) or medium dose (10(5) cfu) of subcutaneous BCG, but the medium dose of BCG produced stronger cell-mediated immune res ponses to bovine purified protein derivative (PPD) after vaccination. Vaccination intradermally with 10(9) heat-killed M vaccae did not prot ect cattle against an experimental challenge with M bovis and induced only weak cell-mediated immune responses to bovine PPD.