[Identification of differential genomic genes of Mycobacterium tuberculosis H37Rv and attenuated strain H37Ra by suppression subtractive hybridization].

To study the virulence-related genes in Mycobacterium tuberculosis, we used suppression subtractive hybridization to clone the differential genomic genes between Mycobacterium tuberculosis virulence strain H37Rv and attenuated strain H37Ra. All of 54 different genes were cloned, sequenced and analyzed by Southern-blotting. Two different DNA fragments in H37Ra are new genes so far, and get the new Genbank number AY534505 and AY560011. Eight different DNA fragments in H37Rv were obtained. One is the fragment of a gene coding virulence factor mce; one fragment belongs to the gene coding for purC synthenzyme; one for PE family protein; the other 4 fragments for putative gene; and the last one is a non-coding fragment. PCR analysis indicated that 2 of the different genes were present exclusively in the clinical virulent strain and in H37Rv, but not in the clinical avirulent strain and in H37Ra. The novel differential genes may provide an important clue for studying the mechanism of M. tuberculosis pathogenesis.