Investigation on the Polymorphisms of the RD's Region in Mycobacterium Tuberculosis Subtypes

Tuberculosis epidemiology is valuable for control of TB by understanding the transmission dynamics. A potential molecular epidemiology method to distinguish the origins of Mycobacterium tuberculosis is region of differences (RDs) polymorphisms. Worldwide, 68 RDs have been specified, so far. By studying deletion and polymorphisms in the RD regions of RD1, RD150 and RD181, this study focused on the molecular diversity of Mycobacterium tuberculosis in Iran for the first time. One hundred ninety Mycobacterium tuberculosis strains were isolated from patient’s clinical samples in Mycobacteriology Research Center (MRC). DNA was extracted and spoligotyping was performed by using DR region PCR. The spoligotyping patterns were obtained from SPOLDB4 database. Drug susceptibility tests were performed for all isolates and finally, three regions of RD1, RD150 and RD181 loci were amplified by PCR. Out of 190 M. Tuberculosis strains, 70% of isolates were susceptible to Isoniazid, Rifampin and Etambutol drugs and the remaining (30%) were drug resistant. The spoligotyping patterns demonstrated H4 (127) and CAS families were more prevalent than other families by 37.5% and 20% respectively. Other prevalent families were T1 (9.5%), Beijing (11%) and unknown families (27%). The RD181 loci had deletion in Beijing strains, and RD1 showed deletion in BCG strains. The RD150 loci showed deletion in none of the strains. The RD1 and RD181 are appropriate to identify BCG and Beijing strains respectively. Whereas, RD150 loci is not efficient to show polymorphisms in various strains. As a result RD1 and RD181 polymorphism detection can be used effectively for molecular epidemiology studies to determine ongoing transmission clusters.