FIG 6 .

phSP6-ProPol determined H37Rv susceptibility to first-line antitubercular antibiotics with a high signal-to-noise ratio. H37Rv was either left untreated or treated with rifampin, isoniazid, streptomycin, or ethambutol for 16 h or 40 h. Bacteria were then infected with phSP6-ProPol for 4 h. RNA was isolated, purified, and amplified using RT-PCR. The resultant product was separated by 2% agarose gel electrophoresis and was stained with ethidium bromide. Dilutions (1:10 and 1:100) of cDNA from the untreated controls were made prior to PCR amplification to provide a semiquantitative estimation of the effect of each drug on SML synthesis during infection of drug-susceptible M. tuberculosis. The locations and molecular weights of DNA size markers in lane M and the location of the SML signal are indicated.