Leprosy Vaccine Research Articles

Leprosy.

Leprosy affects over 10 million people in the world. The disease is a model of graded cell-mediated immunity, in this case to the causative organism, Mycobacterium leprae. The clinical manifestations are due to (i) bacterial progression, (ii) immunologic responses of the host, (iii) peripheral nerve damage due to either or both bacterial progression and immunologic responses of the host, and (iv) preventable secondary deformities following nerve damage, which account for most of the stigma of the disease. Treatment modalities are now available to control or minimize the effects of bacterial progression, harmful immunologic responses of the host, peripheral nerve damage, and secondary deformities. Unique biochemical characteristics of M. leprae reside in the cell wall and associated macromolecules. Some of these molecules are potent immunogens in humans, while others constitute the structural integrity of the bacillus. Proteins of M. leprae are currently under intensive investigation as a result of deoxyribonucleic acid cloning of M. leprae genes. Structure-function and antigenic relationships of M. leprae proteins should become available by using recombinant deoxyribonucleic acid procedures coupled with T- and B-cell cloning to advance our understanding of the immunologic reactions encountered in Hansen's disease. Until recently, the study of the immunology of leprosy has been stymied by the lack of immunologically specific M. leprae antigens. The definition of specific antigens and production of recombinant and synthetic immunologic reagents have fostered state-of-the-art research efforts into new immunodiagnostic procedures and development of a leprosy vaccine. Also discussed is progress in understanding of the mechanism(s) underlying the M. leprae-specific immunodeficiency associated with lepromatous leprosy, including the role of suppressor T cells and defective macrophage function. Metabolic studies of M. leprae suggest intact catabolic pathways and energy generation with purine bases and catalase as possible growth factors. Special attention may also need to be given to biophysical parameters for eventual in vitro cultivation. Rapid in vitro systems, using quantitation of bacillary metabolic activity, may soon replace the lengthy mouse footpad test for determining the viability and drug susceptibility of the leprosy bacillus.

Disputes delay development of leprosy vaccine for India

Disputes delay development of leprosy vaccine for India

Inactivation methods of Mycobacterium leprae as a leprosy vaccine

Convit used the mixture of heat-killed leprosy bacilli and live BCG as a leprosy vaccine. It seems that some devices could be applied to inactivate the bacilli instead of heat-killed bacilli of Convit's vaccine. When heat-killed bacilli were inoculated to mouse, many stainable acid-fast bacilli were detected in the injected site for a long time. However, in the case of live leprosy bacilli, stainable acid-fast bacilli disappeared comparatively ear-lier in the injected area. Leprosy bacilli of live but defected growth ability may be more efficient for vaccine than heat-killed bacilli.Purified leprosy bacilli were prepared from leproma produced in nude mouse foot pad infected with Mycobacterium leprae, Thai-53 strain, by ficoll gradient centrifugation me-thod and treatment of 1 N sodiumhydroxide. The bacillary counts were 1.6×1010 in 16.3ml of 0.1M P. B. (pH 6.4). The first group of nude mice were inoculated with live bacilli into their right hind foot pads, the second group were injected with heat killed bacilli, the third group were injected with formalin treated bacilli, the fourth group were inoculated with rifampicin treated bacilli, the fifth group were injected with Co60 irradiated bacilli and the sixth group were injected with bacilli cultivated on Ogawa egg yolk medium for 4 months. The first to the third groups consisted of 5 mice and the fourth to sixth groups consisted of 8 mice. Bacterial suspension of 0.05ml were injected in right hind foot pad. For the first to the third groups, observation was carried out at 14 months after inocula-tion and for the fourth to the sixth groups, one mouse was killed every 2 months. Bacterial numbers in the foot pad were counted. In the first group injected with live bacilli, all 5 mice produced lepromas in the injected sites of right foot pads. In the second group injected with heat-killed bacilli, bacterial count was not done because of some trouble. In the third and fifth groups injected with the formalin treated and Co60 irradiated bacilli respectively, bacterial counts were almost the same in the 0 time and after 14 months as seen in Table 1. In the sixth group injected with the cultivated bacilli, the bacillary counts after 14 months were less than that of 0 time and their acid-fastness were weak. In the fourth group, the bacilli treated with rifampicin grew gradually in the foot pads at 8 months after injection and reached to 10 times growth after 14 months.Leprosy bacilli kept in the ordinary medium at 33°C for 4 months may be regarded as dead bacilli. Moreover, if they have been treated with rifampicin, they are probably inactive in growth. If nude mice could not produce leproma in foot pad after injection of leprosy bacilli kept in culture media for a long time, the cultivation method would be hopeless.

Leprosy vaccine: Large-scale trials begin in India

Leprosy vaccine: Large-scale trials begin in India

Leprosy vaccine: Malawi trial to be launched

Leprosy vaccine: Malawi trial to be launched

Leprosy vaccine: Clinical trials begin in Norway

Leprosy vaccine: Clinical trials begin in Norway

Leprosy Vaccine Trials to Begin Soon

Leprosy Vaccine Trials to Begin Soon

New Push for Tropical Medicine

One billion persons, mostly in the world's poorer countries, suffer from intestinal parasite infections; half a billion people have malaria; a quarter of a billion carry parasitic worms in their blood or lymphatic system or both. Leprosy affects more people today, because of population growth, than in biblical times, when it was one of the most widely described and dreaded diseases. These and other ailments, usually lumped together as diseases, have not benefited as much from the recent triumphs of biomedical research as those illnesses more frequent in developed countries, and the World Health Organization (WHO) is preparing to launch a major new attack on these ancient scourges. The reason behind the lag of tropical medicine is not hard to find: Only one percent (some $25 million annually) of all the money spent on medical research is devoted to diseases of tropical and subtropical countries-though more than half the world's population lives in these areas. Increasingly, research in industrialized countries is directed toward the chronic diseases that afflict a population that lives longer than most inhabitants of poorer countries-heart disease, cancer and mental disorders. Even the potentially useful spin-offs of such research are often not applied to improving health in tropical areas because trained personnel and local facilities are missing. After looking into the problem, WHO's Advisory Committee on Medical Research concluded that radical measures are needed to remedy this deplorable situation. The proposed cure is as ambitious as it is radical. Noting the success of internationally sponsored, regional agricultural research laboratories-which produced the Green RevolutionWHO iS planning a similar network of regional medical institutes that would conduct basic research, apply the results to practical health problems of an a!rea, coordinate the work of national labs and train local personnel from technicians to postdoctoral-level researchers. The annual cost of the new program, when operational, will probably run between $10 million and $15 million, far more than the present WHO budget will allow, so outside donors, including governments and foundations, are. being asked to help. A meeting of potential donors is tentatively for March. In an interview with SCIENCE NEWS at WHO headquarters in Geneva, medical officer Howard Goodman described the first step in implementing the program: establishment of a multidisciplinary research and training institute for the study (primarily) of parasitic diseases in N'dola, Zambia. The Zambian government has donated two upper floors of a new, seven-story hospital for the project and officials hope to get the institute operating next year. Goodman emphasizes that this is to be no ivory tower science, but rather a directed effort to develop drug therapy and possibly vaccinations against a specific set of diseases. Recent advances in the study of how the body's immune system recognizes the agents of infection and mobilizes antibodies to attack them may lead to new methods of treating and even preventing diseases involving protozoa, such as malaria and trypanosomiasis (sleeping sickness). The one-celled, animallike protozoans are recognized in the body by certain surface substances called antigens, and research will concentrate on how to strengthen the immune response triggered by these substances. The main problem is that protozoa continually change their antigens and so evade the defending antibodies. Scientists at the new institute will thus concentrate on enhancing immunity by determining the pattern of antigen variations and finding out how various drugs affect these variations. Their research will also involve studies of cell membranes-now a popular topic in Western laboratories because of its importance to understanding the mechanism of cancer. Thus the flow of information between N'dola and established centers of research in developed countries should not be one-sided. A WHO panel setting up research goals for the new program concluded that rapid progress towards a leprosy vaccine is now possible, and recommended a major effort in this direction. Here, research will be concentrated on N'dola hospital, Zambia: Home of new institute for study of parasitic diseases.

The initiation of a trial of B.C.G. vaccine for leprosy

The initiation of a trial of B.C.G. vaccine for leprosy