Figure 4.

Transcription of M. tuberculosis H37Rv genes during growth in Middlebrook 7H9 broth (A) or human macrophages (B) as detected by cDNA probes prepared by SCOTS. Bacterial cDNA probes prepared by three rounds of SCOTS (see text) from broth cultures grown to an OD (A₆₀₀) of 0.4 or from intracellular bacteria 48 h after infection were hybridized to PCR-amplified plasmid fragments containing the indicated H37Rv genes (lanes 1–4) or cloned bacterial cDNA fragments isolated from macrophage-grown bacilli. mig (150 bp) is an M. avium DNA fragment not present in M. tuberculosis. The H37Rv genome coordinates of specific sequences are available on request.