Immunochemical and structural integrity of surface protein antigens of mycobacteria during separation from armadillo liver tissue.

Surface proteins of Mycobacterium smegmatis were iodinated using the lactoperoxidase method. Sodium dodecyl sulfate polyacrylamide gel electrophoresis demonstrated two major surface proteins in the radiolabelled M. smegmatis. Both surface proteins were released from M. smegmatis using the nonionic detergent Triton X-100. The major surface component was sensitive to pronase digestion and contained no detectable carbohydrate. The second radiolabelled component was found to be of low molecular weight, resistant to pronase digestion and stained positive for carbohydrate by the periodic acid/Schiff method. Triton X-100 solubilized radiolabelled surface proteins were antigenic as assessed by a radioimmune precipitation test. When surface labelled M. smegmatis was mixed with armadillo liver tissue and separated from tissue using a method formerly employed by the World Health Organization Immunology of Leprosy Program for the purification of M. leprae, as much as 50% of the surface proteins of M. smegmatis was either released or destroyed. In addition, another twenty distinct proteins were released from M. smegmatis after treatment with Triton X-100. Similar losses of proteins from M. leprae may also occur using this procedure for M. leprae purification. Separation techniques employing surfactants and enzymatic treatment should be carefully evaluated since proteins lost during these procedures may prove relevant to human immune responses to M. leprae.