Susceptibility to murine leprosy bacilli of nude mice.

Comparative observations were made on the development of experimental murine leprosy in various inbred strains of mice, including nude mice of congenital thymic aplasia. The susceptibility of these strains of mice to murine leprosy bacilli was evaluated by the development of leproma at the subcutaneous infection site and also by the involvement of visceral organs. Nude mice developed a much more severe disease than C3H mice which is the representative of the malignant type. Their high sensitivity was also demonstrated in the case of intraperitoneal infection. The observations in nude mice and other mouse strains confirmed our concept that experimental mouse leprosy can be classified into three clinical types, benign, intermediate and malignant, and suggested that such mouse strain differences are related with their cell-mediated immunity.