A genomic study on the cultivable and nerve invading Mycobacterium HI-75 after the recovery 3 months of the inoculation to nude mice.

The sequence of the polymerase chain reaction (PCR) product of 16S ribosomal RNA (16S rRNA) of the leproma-derived and cultivable Mycobacterium HI-75 (M. HI-75) which was obtained from the infected regions of inoculated mice, was examined and compared with that of the cultured bacteria by the direct sequencing techniques. The sequence was completely consistent with the cultured bacilli in the comparable 837 bases of 16S rRNA. The mycobacterium examined in this study was originally isolated as M. leprae (ML) by Skinsnes, et al. in 1975 from leproma of a lepromatous type Hansen's disease patient and therefore named as Mycobacterium leprae HI-75 by them, and was maintained from 1984 using either Ogawa's or Sauton's media in the beginning and Ogawa's medium enriched with glucronic acid and N-acetyl-D-glucosamine recently. Sasaki and Hamit reported the nerve invasion and the growth of the inoculated bacilli either to the nude mice or the I131 treated immunocompromised Swiss mice. We previously reported that cultured HI-75 was most similar to M. scrofulaceum by the direct sequencing of the gene of 16S rRNA. The 16S rRNA obtained from the mouse tissue in the present study indicated that M. HI-75 would be a variant of M. scrofulaceum possessing an ability to invade into peripheral nerve. The results suggest that the HI-75 strain claims a nature as a pathogen to develop a leproma-like lesion.