ON THE CATALASE-PEROXIDASE GENE, KATG, OF MYCOBACTERIUM-LEPRAE AND THE IMPLICATIONS FOR TREATMENT OF LEPROSY WITH ISONIAZID

The toxicity of the potent tuberculocidal agent, isoniazid, is mediate d by the heme-containing enzyme, catalase-peroxidase, encoded by the k atG gene. Although isoniazid has been used for the treatment of lepros y, it is shown here that the katG gene of Mycobacterium leprae-is a ps eudogene, which has probably been inactivated by multiple mutations. I nactive genes were detected by the polymerase chain reaction in severa l isolates of M. leprae, of different geographical origins, and attemp ts to complement an isoniazid-resistant strain of Mycobacterium smegma tis with the katG pseudogene were unsuccessful. Isoniazid is thus like ly to be of no therapeutic benefit to leprosy patients.