FIG 5.

Confirmation by Southern blotting of the rapid in vitro selection of the 350-kb duplication in East Asian M. tuberculosis isolates. DNAs obtained after being passaged in vitro for different amounts of time (Fig. 4) were digested with HindIII and SspI, and Southern blots were hybridized to either dosR (A)- or alr (B)-specific probes. In each case, the presence of two bands is indicative of the presence of the 350-kb duplication. DNA of isolate GB41.2 was included as a positive control for the presence of the duplication and from H37Rv as a negative control. The number of passages (pass) corresponding to each of the DNA samples is indicated.