Influence of T-2 toxin on BCG vaccine efficacy against murine pulmonary tuberculosis

Unvaccinated mice were treated with T-2 toxin either 6 days before or 1 day after exposure to aerosols of virulent Mycobacterium tuberculosis. Mice were also treated with T-2 toxin 6 days before vaccination with Mycobacterium bovis (BCG). There was a T-2 toxin mediated increase in the number of viable vaccine organisms recovered from the spleens of toxin-treated mice at 3 weeks after vaccination, and splenomegaly at post-vaccine weeks 3 through 5. At the seventh week after vaccination, toxin-treated vaccinated, toxin-treated non-vaccinated, vaccinated, and untreated mice were exposed to aerosols of viable M tuberculosis. The number of viable mycobacteria in the lungs was determined at weeks 3, 5, 7, and 9 after pulmonary infection. The number of viable tubercle bacilli recovered from the lungs of vaccinated mice was significantly lower than from unvaccinated mice. However, T-2 toxin-treatment did not alter the vaccine efficacy.