Genetic relationships among Mycobacterium leprae, Mycobacterium tuberculosis, and candidate leprosy vaccine strains determined by DNA hybridization: identification of an M. leprae-specific repetitive sequence

Abstract

DNA hybridization studies of genomic DNA indicated that, while different isolates of armadillo-derived Mycobacterium leprae have a high degree of homology, binding of M. leprae genomic DNA to DNA of other species of mycobacteria or to corynebacteria was low, establishing that M. leprae is only remotely genetically related to any of the species examined. Several candidate leprosy vaccine mycobacterial strains were similarly found to have little genetic similarity to M. Ieprae. In contrast, the DNAs of the slow-growing mycobacteria M. tuberculosis, M. africanum, M. bovis, and M. microti were found to be very closely related. In the course of these studies, an M. keprae-specific repetitive sequence, greater than 15-fold per genome equivalent, was identified that might be useful for diagnostic and epidemiological studies. Percent binding of probe DNA Sample DNA M. leprae M. tuberculosis, Low stringency High stringency high stringency M. leprae grown in armadillos Single inoculum Mixed inoculum Leprosy-associated Corynebacterium strains 2628 L.B. Shep IV Other Corynebacterium strains C. diphtheriae type gravis C. diphtheriae type mitis Corynebacterium sp. strain 813 Candidate leprosy vaccine strains ICRC bacillus Mycobacterium strain w R1-7 FMR bacillus M. tuberculosis complex strains M. tuberculosis (Erdman) M. tuberculosis H37Rv M. bovis (TMC 409) M. bovis BCG (Pasteur) M. africanum (TMC 5122) M. microti (TMC 1601) Other mycobacteria M. avium (TMC 724) M. chelonei (TMC 1544) M. fortuitum (TMC 1529) M. gordonae (TMC 1324) M. intracellulare (TMC 1406) M. kansasii (TMC 1204) "M. Iufu" M. marinum (TMC 1218) M. nonchromojenicum (TMC 1481) M. phlei (TMC 1548) M. scrofulaceum (TMC 1320) M. smegmatis (TMC 1515) M. vaccae (TMC 1526

DNA hybridization analysis of mycobacterial DNA using the 18-kDa protein gene of Mycobacterium leprae

“…The blots were washed with light agitation for 90 min either under low stringency conditions (60°C, 3 x SSC and 0.1% SDS) or under high stringency conditions (75°C, 0.3 x SSC and 0.1% SDS). The low and high stringency conditions selected for hybridization and washing, with the 611-bp probe (G + C content 52.38%) were similar to the conditions employed for other mycobacterial DNA hybridization-based studies [16,19,20]. Hybridization signals were detected by autoradiography with an exposure time of at least 24 h. The blots were exposed for up to 5 days to evaluate those negative and weakly-positive hybridization signals observed by autoradiography at 24 h.…”

A family of dispersed repeats in Mycobacterium leprae

“…Mycobacterium teprae, the aetiologic agent of leprosy, is one of the few obligate pathogens that cannot be grown in synthetic medium. It was recently reported that this important, but poorly understood, bacterium contains repetitive DNA (Clark-Curtiss and Docherty, 1989;Grosskinsky et al, 1989), As repetitive sequences, although useful diagnostic tools, can considerably complicate hybridization analysis and genome mapping projects such as the one underway in this laboratory, it became critical to characterize this element further. In the present study, a detailed molecular analysis is reported.…”

Antimycobacterial activity of methdilazine (Md), an antimicrobic phenothiazine

“…terrae 1450, M. tuberculosis H,,Ra 16 and H,,Rv (102,KI,K2). Two other strains known as the 'ICRC' (Grosskinsky et al 1989) and 'Skinsnes' bacillus (Dharmendra 1985), which had been isolated from human leproma and found to be members of the M . avium-intracellulare-scrojiulaceum complex, were also included in the study.…”

“…The 'Skinsnes' bacillus was, moreover, related to M. marinum (Dharmendra 1985). The rapidly growing strains comprised M. fortuitum 1529, M. smegmatis 798, 1546, and M. flavescens 1541(Harboe 1985Grosskinsky et al 1989;Parker & Duerden 1990). The minimum inhibitory concentration (MIC) of Md, Sm, Rf and m-D with respect to different strains was determined by tube dilution in Kirchner's liquid medium (KLM;Kirchner 1932).…”