An association between schistosomes and contrapsin, a mouse serine protease inhibitor (serpin).

An antigen in homogenates of adult Schistosoma mansoni worms grown in mice, and immunoprecipitated by polyspecific rabbit antiserum, has been identified as contrapsin, a mouse serine protease inhibitor (serpin). In the serum of some mice infected with S. mansoni contrapsin was found with altered immunoelectrophoretic characteristics when compared with contrapsin from uninfected mice.