Formation of antibody against Mycobacterium leprae antigen 7 in armadillos.

A radioimmunoassay developed to measure antibody against Mycobacterium leprae antigen 7 in man was applied to the nine-banded armadillo (Dasypus novemcinctus). Normal armadillo sera had low but significant antibody activity in the test. Fourteen of 17 armadillos with systemic mycobacterial infection after inoculation with M. leprae showed increased antibody activity in the assay, and in some instances the activity was higher than in a pool of sera from patients with lepromatous leprosy. Crossed immunoelectrophoresis with armadillo serum in the intermediate gel revealed antibodies against five distinct antigenic components of M. leprae. Development of systemic mycobacterial infection after inoculation with M. leprae is thus associated with a distinct humoral immune response. The use of radioimmunosassay for selection of animals for inoculation and for following the development of the infection is discussed.