Figure 3.

Correlation of CFU with the copy number of 16S rRNA from M. tuberculosis growing in the lungs of WT and IFN-γ^−/− mice. Lungs were harvested from M. tuberculosis-infected mice at selected times during infection. (A) Half the lung (attached to the right bronchus) was used to quantitate the number of copies of 16S rRNA by molecular-beacon real-time RT-PCR, and the other half (attached to the left bronchus) was used to determine the number of CFU. The data points shown in the figure represent mean (±SD) of data (expressed in log units) per lung obtained from four animals per time point per mouse strain. (B) Correlation curve for CFU and 16S rRNA copies (in log units) obtained with lungs from WT and IFN-γ^−/− mice pooled together. Correlation coefficients obtained separately with WT mice (R² = 0.9536) and with IFN-γ^−/− mice (R² = 0.9570) were similar to that shown in B.