Lepromatoid Lesion Developed in Nude Mouse Inoculated with Mycobacterium leprae

Animal Transmission of Leprosy

Abstract

Eight of 5 weeks old nude mice (BALB/c-nu/nu) were infected with Mycobacterium leprae obtained from a case of the relapse lepromatous leprosy patient, and they were kept under SPF (specific pathogen free) condition in Vinylplastic-isolator to prevent wasting disease and other microbial infection. All of 3 mice survived for more than 17 months after the infection showed swelling of foot pad at the inoculation site. These 3 mice were sacrificed at 17th, 19th and 22nd month after inoculation respectively, and histopathological and bacteriological examinations were carried out. Histopathologically, lepromatoid lesions were observed not only in the foot pad of the infected site but also in low temperature parts of the body such as eyelid, earlobe, tail and nose. Invasion of acid-fast bacilli into peripheral nerves was remarkable. The acid-fast bacilli increased in lepromatoid lesions were identified as M. leprae by following identification tests: 1) Failure to growth on artificial media, 2) No granuloma formation in normal mouse, 3) Loss of acid-fastness by pyridine extraction, 4) Positive D-dopa oxidase activity, and 5) Results of lepromin reaction with patients.