Susceptibility of severe combined immunodeficient (SCID) mice to Mycobacterium leprae: multiplication of the bacillus and dissemination of the infection at early stage.

Inoculation of M. leprae were made into the both hind feet at a dose of 4.8 x 10(6) bacilli per foot in order to determine the susceptibility to M. leprae of SCID mice which is severely deficient in both T- and B cell immunity. SCID mice was found to have an extremely high susceptibility to M. leprae, and the progress of infection observed in the SCID mice were shown a rapid systemic spread of infection at the all over the tissues as well as the growth of the leprosy bacilli at the site of inoculation. Therefore, SCID mice can be used as a suitable multibacillary model for the study of leprosy.

The experimental inoculation with Mycobacterium leprae in autoimmune mice: results of MRL/lpr mice inoculated into the right hind foot (continued).

Using MRL/lpr, NOD and Crj:CD-1 (ICR) mice, inoculations of M. leprae were made into the right hind foot at a dose of 5.8 x 10(6) bacilli per foot in order to study the influence of the immunobiological characteristics of their mice on the growth of M. leprae. To summarize of the results, MRL/lpr mice showed the high susceptibility to M. leprae, while that of NOD mice were poor. In conclusion, the immunobiological characteristics of MRL/lpr, autoimmune mice bearing lpr gene had effect on the multiplication of M. leprae, this mouse is a suitable multibacillary model for the study of leprosy.

Failure to validate the growth of Mycobacterium leprae on M-Y 14b agar medium.

Confirmation experiments on colony formation of M. leprae on the M-Y 14b agar medium developed by Murohashi and Yoshida were carried out for two years independently by individual members of an organized research group, according to the method described by Murohashi and Yoshida. The results obtained can be summarized as follows: a) No colony production by M. leprae on M-Y 14b agar medium was seen. b) No increase in the number of cells of M. leprae on M-Y 14b agar medium during cultivation was seen. c) Light and electron microscopic observation indicated that there was an increase in the number of non-solid bacterial cells and ghost cells with time of cultivation. d) It was found by mouse foot pad inoculation that four of six samples of M. leprae used as inocula were definitely viable. e) By means of mouse foot pad inoculation, it was shown that viability of M. leprae inoculated onto M-Y 14b agar medium was lost within approximately seven weeks of cultivation. From these results, can be definitely concluded that there is no evidence indicating that multiplication of M. leprae took place on M-Y 14b agar medium.

The nude mouse as an experimental lepromatous leprosy model: the enhancing effect of thymus cells in infected / ?

In sumary, it may well be conculuded that the nude mouse with thymus cell grafting as a severe lepromatous leprosy model was developed in C57BL/6-nu/nu as well as CF#1-nu/nu, comparing with untreated nude mice. In addtion, comparison of sex in treated group, susceptibility to M. leprae in the some males were higher than in foot swelling of the females, also, difference of individuality occured in both sex at a latter stage after infection, therefore, further investigation is under way to look for preferable nude mouse and hairless-athymic mouse which they are established by ourselves