Affiliations: *Thai National Institute of Health, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand
**Department of Microbiology, Immunology and Pathology, Colorado State
University, Fort Collins, Colorado, USA
Source: Proceeding: 40th US-Japan Conference on Tuberculosis 2005; 227
The genetic diversity of Mycobacterium leprae isolates from Thai leprosy patients was investigated using the TTC repeat and the tandem repeat in the rpoT gene as genetic markers. M. leprae DNA of clinical isolates was obtained from skin biopsies of multibacillary patients living in remote areas and in suburban Thailand where leprosy is in low prevalence. In M. leprae strains of 55 multibacillary patients, the TTC repeat region showed variations of 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 24 and 25 repeats. It was found that the most common repeats of TTC in Thai clinical isolates are 15, 16 and 19. All isolates contained three copies of GACATG repeat in the rpoT gene and no variation in copy number was found. The application of TTC repeats in tracking of leprosy transmission in one family where three leprosy patients were identified revealed a single strain of M. leprae harboring 15 copies of TTC repeat. This preliminary study indicates that the TTC region may be useful as a genetic marker for strain differentiation and for epidemiological investigation of leprosy.The application of other different genetic markers may enhance discrimination of M. leprae strains.