[Genomic polymorphism in Mycobacterium tuberculosis strains]

Different genomic fingerprinting techniques (universal probes, such as rRNA genes, phage M13 DNA, IS 6110 probe) have been used to investigate the genomic polymorphism of Mycobacterium tuberculosis strains isolated in different geographical regions of Russia and in some CIS countries. As shown with the use of these techniques and a specially developed PCR-mediated system for genetic typing, M.tuberculosis strains are genotypically heterogeneous in regions with a sporadic level of tuberculosis morbidity and genotypically homogeneous in regions with elevated morbidity and mortality levels. The evaluation of the effectiveness of the genetic typing of M.tuberculosis with the use of different genomic fingerprinting techniques has made it possible to propose the optimum 3-stage scheme for the differentiation of M.tuberculosis strains: (1) the typing of all isolated strains of the PCR-mediated test system; (2) the typing of several selected M.tuberculosis strains with the use of 1S 6110 probe (2-3 strains of each detected PCR-RFLP [correction of PLRF] genotypes); (3) the typing of M.tuberculosis strains, containing 1 copy of 1S 6110 or not containing such sequence, with the use of probes (phage M13 DNA) detecting hypervariable sequences in M.tuberculosis genomes.