FIG. 10.

Growth of an aerosol inoculum of virulent M. tuberculosis in the tissues of both vaccinated and unvaccinated mice. Unvaccinated BALB/cJ mice were challenged by the respiratory route with approximately 300 CFU of virulent M. tuberculosis or were challenged 9 weeks postvaccination with either BCG-P or M. tuberculosis H37Rv ΔleuD strain mc²3032. At various times postchallenge, the mice were sacrificed and their organs were collected and homogenized. The bacterial burdens in the livers (A), spleens (B), and lungs (C) were determined by serial dilution and plating of the homogenates as described in Materials and Methods. The error bars represent the standard deviations for the means of four to five mice per experimental group.