ABSTRACT
Nine-banded armadillos were intravenously infected with 10(9) M. leprae. IgM antibodies to PGL-I were evaluated three times during the six months before and every two months after the infection. A thorough autopsy examination was done on animals that died or were sacrificed at intervals of 3, 4, 6, 12, 15 and 18 months after the infection. Three animals which had acquired the infection in the wild and one experimentally infected animal showed significant increases in antibody levels corresponding to their high bacterial load. In the other five experimentally infected animals, M. leprae infection was established in the cells of the reticulo endothelial system (RES) long before the IgM antibody levels to PGL-I became positive. It is possible that in human leprosy also M. leprae may enter and multiply in the RES initiating antibody production during the incubation period before clinical disease with neuritis becomes manifest.