Genotyping of Mycobacterium leprae on the Basis of the Polymorphism of TTC Repeats for Analysis of Leprosy Transmission

Abstract

The polymorphism of TTC repeats in Mycobacterium leprae was examined using the bacilli obtained from residents in villages at North Maluku where M. leprae infections are highly endemic (as well as from patients at North Sulawesi of Indonesia) to elucidate the possible mode of leprosy transmission. TTC genotypes are stable for several generations of passages in nude mice footpads and, hence, are feasible for the genotyping of isolates and epidemiological analysis of leprosy transmission. It was found that bacilli with different TTC genotypes were distributed among residents at the same dwelling in villages in which leprosy is endemic and that some household contacts harbored bacilli with a different genotype from that harbored by the patient. Investigations of a father-and-son pair of patients indicated that infections of bacilli with 10 and 18 copies, respectively, had occurred. Genotypes of TTC repeats were found to differ between a son under treatment and two brothers. These results reveal the possibility that in addition to exposure via the presence of a leprosy patient with a multibacillary infection who was living with family members, there might have been some infectious sources to which the residents had been commonly exposed outside the dwellings. A limited discriminative capacity of the TTC polymorphism in the epidemiological analysis implies the need of searching other useful polymorphic loci for detailed subdivision of clinical isolates.Leprosy is a chronic infectious disease caused by Mycobacterium leprae infection. It has long being believed that the source of infection is untreated leprosy patients. It has also been predicted that multidrug therapy (MDT) with strong bactericidal antibiotics (such as rifampin) would reduce the source of infection and consequently interrupt further transmission to others. The number of new cases, however, has shown no substantial decline even though MDT with strong bactericidal drugs has been used in the past two decades. It is reported that about 600,000 to 700,000 new cases are continuously found in the world every year (20), which suggests that the transmission of leprosy bacilli still occurs, especially in countries of endemicity. Elucidation of the mode of transmission would be essential to help prevent new infection. The differentiation of strains of leprosy bacilli by genomic polymorphism might be of great value in efforts to understand the mode of transmission of the disease.The range of molecular techniques for epidemiological analysis has expanded in recent years, and there are now many genotypic methods that allow a high level of discrimination between bacterial strains. Restriction fragment length polymorphism analysis, which is the method most widely used for molecular epidemiology of tuberculosis, is not applicable for leprosy, since M. leprae cannot be grown in artificial medium, and almost no divergence was found by this fingerprinting assay (19). Shin et al. discovered a genomic divergence of M. leprae by the variation of TTC repeats (17) and subdivi...

Diversity of Potential Short Tandem Repeats in Mycobacterium leprae and Application for Molecular Typing

“…In light of the transmission mode, human-to-human direct contact was first generally accepted (6, 16), with time as airborne (23), as vector-borne (14, 25) and as vehicle-borne (3, 12) routes from evidence that has been obtained. All the progress in leprosy epidemiology was helpful in understanding the chain of transmission, yet at the same time was overwhelming.In the past few years, studies focusing on leprosy transmission by molecular genotyping have shed new light on it (8,10,11,22,24,27,28). The most recent one was the report from Groathouse et al (8).…”

“…In the past few years, studies focusing on leprosy transmission by molecular genotyping have shed new light on it (8,10,11,22,24,27,28). The most recent one was the report from Groathouse et al (8).…”

“…M. leprae templates from both strains and slit-skin smears were prepared by treatment with lysis buffer at 60°C overnight as described previously (13). PCR amplification of STR sites as well as sequencing analysis was performed under the same condition as described elsewhere using the listed primer pairs (10,11,12,13). Briefly, target loci were amplified using a G mixture and a FailSafe PCR system (EPICENTRE, Madison, Wis.).…”

Variation of TTC Repeat Pattern In The Dna of Mycobacterium Leprae Isolates Obtained from Archeological Bones and Leprosy Patients From East Nusa Tenggara

“…As is the case in several eukaryotic and prokaryotic genomes that have been sequenced, short stretches of DNA that occur in tandem repetitions are also found in M. leprae [6]. Matsuoka [7] first reported that 6-bp sequence (GACATC) was found as two alleles in the rpoT gene of M.leprae. This was followed by the recognition of variable number tandem repetitions (VNTRs) of the TTC triplet in a noncoding region of the M. leprae cosmid MLCB2407 (GenBank accession no.…”

Comparação entre microssatélites e o gene Ml MntH como alvos para a identificação do Mycobacterium leprae por PCR na hanseníase

“…6 The diagnostic primers tested in this study were previously used for epidemiological mapping of the M. leprae bacillus in inter alia India, Indonesia and the Philippines. 4,7,8 However, these primers have not been routinely used given the difficulty of obtaining samples of genomic DNA from clinical material.…”