Molecular identity of a major antigen of Schistosoma mansoni which cross-reacts with Trichinella spiralis and Fasciola hepatica

A glycoprotein cross-reactive among Schistosoma mansoni, Trichinella spiralis and Fasciola hepatica was identified and characterized by use of monoclonal antibodies prepared against S. mansoni glycoproteins. Four monoclonal antibodies recognized the same antigen which was one of the major S. mansoni glycoproteins precipitated by sera of hosts infected with either S. mansoni or T. spiralis. This antigen was expressed in S. mansoni cercariae, adult male and female worms, and eggs, and in S. haematobium but not in S. japonicum. Radio-immunoprecipitation and partial proteolytic digest mapping showed that the monoclonal antibodies each recognized a unique epitope. These epitopes were heat labile, sensitive to chaotropic agents, but resistant to reduction and alkylation or digestion with glycosidases, indicating that the recognition sites were amino acids and not carbohydrates. Epitopes recognized by the four monoclonal antibodies were expressed in F. hepatica, whereas only two were expressed in T. spiralis. Analysis by immunofluorescence microscopy showed that the antigen was expressed in S. mansoni in the parenchymal tissue and on the surface of the dorsal tubercles; in mature F. hepatica in the parenchymal tissue, vitelline glands and eggs; in immature F. hepatica only in the parenchymal tissue and in larval T. spiralis in the hypodermis.