Circumoval precipitin antigens for the diagnosis of schistosomiasis. I. Development of an antiserum reactive with Schistosoma mansoni eggs by the circumoval precipitin test.

A serum was developed which reacts with Schistosoma mansoni eggs by the circumoval precipitin (COP) test. This antiserum to COP antigens was prepared by coupling the COP immune complexes to protein A-Sepharose, isolating the complex with acid buffer, and immunizing rabbits with the eluate. The antiserum reacted with S. mansoni eggs, forming globular bleb and septate precipitates. It also reacted in gel diffusion with a soluble egg antigen preparation of S. mansoni (SEA). Of four SEA antigenic components precipitated one was clearly MSA1. The antiserum to the COP antigens had anti-parasite antibodies absorbable with lyophilized cercariae or eggs. Three human immunoglobulins (IgG, IgM, and IgA) were involved in the COP reaction.