Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Antibody responses to the apparently species specific phenolic-glycolipid-1 (Phen-Gl-1) antigen of Mycobacterium leprae were examined in humans and armadillos using enzyme-linked immunosorbent assays (ELISA). Statistical definitions for the interpretation of positive and negative reactions were derived. A retrospective serological survey of armadillos indicated that leprosy in the wild armadillo is a naturally acquired zoonosis. Presently 12.5% of the armadillos in 2 parishes in south central Louisiana have detectable IgM antibodies to Phen-Gl-1. Approximately 2.7% of these histologically exhibit clinical disease. Antibodies were not detected in Florida armadillo sera. Variations in prevalence rates were noted, and may be due to environmental conditions, population characteristics or some intricacies in the transmission of leprosy. Naturally acquired leprosy in the armadillo may be used as a model to study transmission and baseline data have been derived. The ELISA was shown to have application in the management of experimental leprosy infections in armadillos. Resistant armadillos were noted to have an irregular or absent antibody response to the Phen-Gl-1 antigen over the course of an experimental infection. Armadillos infected in the wild also had an irregular IgM response. Susceptible armadillos appeared to have a long-term IgM antibody response to Phen-Gl-1 becoming detectable some 186 days post-experimental infection. This antibody remained detectable for up to 1140 days post-infection. Antibody responses of susceptible armadillos correlated with the harvestable load of M. leprae in liver tissues and ELISA absorbances successfully predicted a harvest result 97% of the time. IgM antibodies to Phen-Gl-1 were earlier and more reliable than other indicators of infection previously applied. IgM, IgA, and IgG antibodies to Phen-Gl-1 were detected in leprosy patients and contacts. IgM appeared to be the predominate isotype detectable. Human patients showed no significant correlation of antibody relative their clinical status. IgM antibodies to Phen-Gl-1 were depressed as a result of therapy with thalidomide. Monitoring Phen-Gl-1 antibodies in human patients is not predictive of patient status or reaction and does not seem indicated for clinical management.