Schistosoma mansoni: antigenic characterization of malate dehydrogenase isoenzymes and use in the defined antigen substrate spheres (DASS) system.

Immunoelectrophoresis of Schistosoma mansoni homogenates against mouse antisera resulted in only one precipitation line, which showed malate dehydrogenase activity. Immunoprecipitins against schistosomal malate dehydrogenase were also demonstrated in sera from individuals with schistosomiasis. Analysis by the double-diffusion method showed that malate dehydrogenase antigens in S. mansoni, S. haematobium, and S. bovis are immunologically indistinguishable. Immunoelectrophoresis of isolated mitochondrial and cytoplasmic malate dehydrogenase, showed that only the mitochondrial enzyme is able to form a malate dehydrogenase active precipitation line. Rabbit antisera directed against purified mitochondrial malate dehydrogenase showed a reaction with the enzyme as judge by immunoelectrophoresis. A purified mitochondrial malate dehydrogenase preparation, coupled to Sepharose 4B, was used in the defined antigen substrate spheres (DASS) test. Sera from experimentally infected mice contained considerably higher levels of antibodies against the mitochondrial malate dehydrogenase preparation than sera from infected individuals.