[The 69th annual meeting special lecture. Present situation of leprosy].

Many leprosy patients have deformity or disability owing to the characteristics of Mycobacterium leprae i.e. M. leprae affects skin and peripheral nerve. Optimum growth temperature of M. leprae was estimated by clinical manifestations and animal experiments, and it was concluded that the optimum temperature is 33 degrees C, and this characteristic of M. leprae may be one of the reason why M. leprae affects skin tissue. There was no reliable treatment of leprosy before 1943, but effectiveness of promin against leprosy was proven in 1943, and chemotherapy of leprosy was gradually improved especially since 1960 after the discovery of mouse footpad inoculation of M. leprae. In vitro cultivation technique of M. leprae is still unestablished, but susceptibility of ninebanded armadillo to M. leprae was discovered in 1970. Supply of M. leprae collected and purified from M. leprae infected armadillo tissue became available, then biochemistry, immunology and molecular biology of M. leprae was improved significantly. Ridley-Joppling's classification of leprosy i.e. two types (tuberculoid and lepromatous) and two groups (indeterminate and borderline) classification is being adopted at present. Rifampicin, DDS (dapsone) and clofazimine (lamprene) are widely used for chemotherapy of leprosy. WHO is recommending Multidrug Therapy (MDT) of leprosy i.e. administration of rifampicin and DDS for paucibacillary group, administration of rifampicin, DDS and clofazimine for multibacillary group. About 2.4 million leprosy patients are registered and under chemotherapy in the world at present, and about five hundred thousand new patients are being registered every year. Target of leprosy elimination by WHO is prevalence rate of leprosy should be less than one per ten thousand in every country.(ABSTRACT TRUNCATED AT 250 WORDS)

Joint chemotherapy trials in lepromatous leprosy conducted in Thailand, the Philippines, and Korea.

Chemotherapy trials in lepromatous leprosy using various combinations of existing antileprosy drugs were conducted jointly by Korea, The Philippines, and Thailand. The general objective of these trials was to determine the most effective and practicable regimen or regimens for field application. Lepromatous patients were divided into two groups: Group I was comprised of new, untreated patients infected with dapsone-sensitive Mycobacterium leprae and Group II consisted of relapsed patients with dapsone-resistant disease. Four different regimens were administered to each group for 5 years. Comparison among the regimens was based on antileprotic efficacy, drug safety, acceptability, field practicability, and economic feasibility. No significant differences were noted among the various regimens as judged by the reduction in the bacterial index (BI), clinical response, and change in biopsy index. Toxicity was seen only in the regimens containing prothionamide and rifampin. The regimens were acceptable to the patients and all were found practical for field use. Clofazimine, even in low doses, was found to suppress the frequency and severity of erythema nodosum leprosum. A multidrug regimen effective against both new and relapsed cases of lepromatous leprosy, whether dapsone sensitive or dapsone resistant, is recommended for field use. Given priority, the cost of the regimens is affordable in the three countries.

Overproduction, affinity purification and characterization of 65-kDa protein of Mycobacterium leprae in Escherichia coli.

The 65-kDa protein of Mycobacterium leprae was produced in an Escherichia coli strain carrying a plasmid harboring the recloned gene coding for the protein. The protein was purified through affinity chromatography prepared with the IgG fraction of a monoclonal antibody which was prepared against the 65-kDa protein. The purified 65-kDa protein also reacted immunologically with the monoclonal antibody IIIE9, which recognizes the epitope for M. leprae, prepared by Buchanan, et al. BALB/c mice were inoculated with M. leprae and 4 months later were skin tested with the purified 65-kDa protein. Gross changes were observed at the skin-test site. The role of the protein in protective immunity against M. leprae foot pad infection in mice was also studied.

Multiplication of Mycobacterium leprae in the nude mouse, and some applications of nude mice to experimental leprosy.

Two aspects of the immune deficiency of nude mice make these animals particularly useful tools for leprosy research. Nude mice are capable of supporting multiplication of M. leprae to levels approaching 10(10) per g in peripheral body tissues. In addition, nude mice may be inoculated with greater than 10(4) (in fact, with as many as 10(8) organisms per foot pad, without provoking an immune response that prevents multiplication of the organisms. Thus, the nude mouse should be particularly suitable for detecting persisting M. leprae in treated patients, and as a model of the patient for evaluating chemotherapeutic regimens.

Restored pathogenicity of attenuated Mycobacterium lepraemurium in mice.

The ability of Mycobacterium lepraemurium (Mlm) to adhere to A31 cells in culture decreased with the number of passages of the bacilli on Ogawa egg-yolk medium. Pathogenic Mlm consistently grew in tissue culture cells but growth was not seen with attenuated Mlm isolated from a smooth colony. After prolonged incubation, attenuated Mlm became adapted to tissue culture growth. The pathogenicity of the attenuated bacilli was restored partially by the adaptation to tissue culture cells and restored almost completely by passage in mice. After restoration of pathogenicity by these methods, the Mlm formed rough-type colonies on Ogawa egg-yolk medium although the colonies were not completely of the rough type. Attenuated Mlm did not interfere with the growth of in vivo-derived Mlm in tissue culture or in mice.

Prophylactic/therapeutic effects and induction of reversal reactions with thymus transplantation in Mycobacterium leprae-infected nude mice.

The study results indicated that thymus transplantation was effective in suppressing the growth of Mycobacterium leprae in the nude mouse, and also suggested that thymus transplantation was effective as immunotherapy of experimental leprosy in nude mice. The histopathological findings revealed the induction of reversal reactions in those animals receiving thymus transplants.

Negative observations on immunological side effects of rifampin and dapsone in mice.

The in vivo effects of rifampin and dapsone on immunological responses were investigated using mice immunized with sheep erythrocytes. The number of cells producing antibody was not affected by a clinical (1 CD) or a threefold excess dose (3 CD) of the drugs administered for ten days. A similar result was obtained in an experiment using a mouse strain known to be low responders to the antigen. Induction of suppressor cells acting on antibody production was not influenced by 3 CD or 6 CD of the drugs. Neither delayed-type hypersensitivity nor induction of the suppressor cell population acting on delayed hypersensitivity was affected by 3 CD of the drugs. Phagocytosis of sheep erythrocytes by peritoneal cells and the growth of a tumor were not altered by 6 CD of the drugs.

Collection method for Mycobacterium leprae from infected armadillo liver.

Leprosy bacilli were separated from infected armadillo liver almost free from tissue contaminants by a Percoll gradient centrifugation. The yield of bacilli was 46.7%. This is a very simple and effective method without enzyme treatment.

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.