Vaccination of guinea pigs with nutritionally impaired avirulent mutants of Mycobacterium bovis protects against tuberculosis

Four nutritionally impaired strains of Mycobacterium bovis produced by ille gitimate recombination were tested for their ability to protect guinea pigs against intratracheal challenge with virulent Al. bovis. All four strains and ill. bovis is BCG induced significant levels of protection as measured by the reduced spread of infection to the spleen and liver. In animals vacc inated with BCG or two of the other strains, the bacterial counts from the lungs were significantly lower than those of the nonvaccinated animals.