[Quantitative analysis of sigma genes expression in Mycobacterium tuberculosis cultures exposed to rifampicin and isoniazid].
The aim of the study was quantitative analysis of five genes encoding Mycobacterium tuberculosis sigma factors sigA, sigE, sigF, sigH, and sigI as well as the 85B reference gene known as the mycobacterial viability marker, in cultures exposed to rifampicin and isoniazid. The mRN levels were assessed using QRT-PCR technique, in the automated system of real time quantification with the ABI PRISM 7700 Sequence Detector System (TaqMan). The number of each analyzed gene transcript copies was expressed as a number of mRNA per 1 eg of isolated total RNA. In cultures exposed to the tested chemicals the number of 85B mRNA copies declined as compared to the controls (without tested chemicals). There was no detectable expression of sigA and sigI in the control cultures. Both, rifampicin and isoniazid induced expression of sigA and sigI genes. The sigE gene expression increased during exposure to isoniazid and decreased under rifampicin exposure conditions. The sigF mRNA was detected neither in the control culture, nor in cultures exposed to rifampicin or isoniazid. Both tested chemicals caused decrease of sigH expression.