ABSTRACT
The mycobacteria are a clearly defined group of bacteria, widespread in soil and fresh water, but including a number of pathogenic species. The pathogenic mycobacteria are capable of growing intracellularly, particularly within macrophages, in susceptible hosts. The two most important pathogens are Mycobacterium leprae and Mycobacterium tuberculosis, the causative agents of leprosy and tuberculosis, respectively. In the study of all infections of importance to man, experimental animals have been used in order to gain a greater understanding of the host-parasite relationship. In leprosy, the use of experimental animals has assumed even greater importance because of our inability to grow M. leprae in vitro. The genetics of susceptibility to mycobacterial infection has been extensively studied in experimental animals. Much interest in this respect has focused on “innate resistance” genes, which are phenotypically expressed at the level of the host macrophage and are independent of an acquired T-cell response.
