Isolation and Characterization of Surface Antigens from Schistosoma mansoni. I. Evaluation of Techniques for Radioisotope Labeling of Surface Proteins from Adult Worms

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Abstract
Radiolabeled surface proteins of adult S. mansoni [from mice] were prepared by in vitro labeling of whole worms, and by labeling freeze-thaw surface membrane extracts. Incorporation of 125I into surface proteins was attempted using the lactoperoxidase, chloramine-T, iodosulfanilic acid and Bolton-Hunter methods. Radiolabeling of whole worms with lactoperoxidase, chloramine-T and iodosulfanilic acid yielded a single protein peak (MW > 100,000) on SDS-PAGE [sodium dodecyl sulfate-polyacrylamide gel electrophoresis] and showed considerable incorporation of label in the lipid fraction. Bolton-Hunter labeling of whole worms yielded 4 major peaks with MW of 100,000, 60,000, 30,000 and 21,000 and minor peaks with MW of 26,000, 36,000, 43,000, 68,000 and 78,000; 3 of the 4 major peaks corresponded to prominent bands in Coomassie blue-stained gels. Although carbohydrate-labeling techniques were not successful, a single carbohydrate band, MW > 100,000, was detected with PAS [periodic acid Schiff] staining. Radiolabeling of freeze-thaw extracts yielded results similar to those obtained with whole worms. EM revealed the tegument to be left intact and undamaged after labeling with the Bolton-Hunter reagent.