Purification and physicochemical characterization of Schistosoma mansoni egg allergen recognized by mouse sera obtained at an acute stage of infection.

A major allergenic component recognized by mouse sera obtained at an acute stage of infection was purified from soluble egg antigen preparation (SEA) of Schistosoma mansoni by anion-exchange chromatography on DE52 and gel chromatography on Sephadex G-150. The purified allergen showed homogeneity by immunoelectrophoresis and by polyacrylamide gel electrophoresis. Its apparent molecular weight was 210,000 by gel chromatography on Sephadex G-200. This purified allergen could bind to Con A-Sepharose 4B, indicating its glycoprotein nature. After amino acid analysis, aspartic acid, glutamic acid, serine and theonine were found as the major amino acids. The allergenic activity was destroyed by heating at 100 degrees C for 60 min and by pronase or periodate treatment. By double diffusion in agar gel, this purified allergen gave a strong single band against acute (8 w) stage serum, which fused to the major band formed by crude SEA. On the other hand, it showed a very faint band against chronic (22 w) stage serum, which is apparently different from the main band formed between crude SEA and the chronic stage serum. When specific IgE or IgG antibody titers in the serum of human schistosomiasis mansoni cases were measured by ELISA using this purified allergen, the results showed good correlation with those obtained by using crude SEA. Thus, this purified allergen is not only a major allergen in the acute stage of murine schistosomiasis but also an allergen in human schistosomiasis mansoni.