FIG 4.

In vitro passaging of M. tuberculosis cultures selects for the 350-kb duplication. Isolates representing the East Asian lineage were cultivated in vitro for up to 7 months with passages every week. Genomic DNA of these samples was purified every 4 weeks, and the presence of the 350-kb duplication was analyzed by PCR using primers JuntA-B and MR3128c-R3. DNA of isolate GB41.2 was included as a positive control for the presence of the duplication, and DNA from the 29th passage of isolate NHN5 was include as a negative control. The number of passages (pass) corresponding to each of the DNA samples is indicated.