An immunogenic Mr 23,000 integral membrane protein of Schistosoma mansoni worms that closely resembles a human tumor-associated antigen.

A Mr 23,000 Ag of the human trematode parasite, Schistosoma mansoni, has been identified by immunoscreening an adult worm cDNA library with antibody affinity purified on the Mr 23,000 to 25,000 integral membrane protein fraction of the parasite. This Ag is immunogenic in infected humans as well as in rabbits exposed to S. mansoni. The protein sequence of the Ag as deduced from cloned DNA sequences is 218 amino acids long and contains four putative transmembrane regions. Of particular significance, the Ag is strikingly similar, with respect to both amino acid sequence (36% identity) and putative domain structure to ME491, a human stage-specific melanoma-associated Ag.