Repetitive DNA sequence of Mycobacterium tuberculosis: analysis of differential hybridization pattern with other mycobacteria.

In order to generate specific DNA probes for Mycobacterium tuberculosis, restriction fragment length analysis was carried out with some of the mycobacterial species that fall within the tuberculosis complex. The presence of specific bands of 5.6 kb and 4.8 kb was revealed in the AluI DNA digest of M. tuberculosis. The hybridization profile of the 5.6-kb AluI DNA sequence, as judged by the Southern blot and dot blot hybridization experiments, revealed the presence of this sequence in M. tuberculosis H37Rv, M. tuberculosis H37Ra, M. bovis BCG as multiple copy and M. kansasii as single copy but this sequence was not present in M. avium, M. smegmatis, or M. vaccae genomes. Genomic clones corresponding to the 5.6-kb AluI fragment from M. tuberculosis H37Rv library made in the lambda gt11 expression vector were isolated.