Surface and species-specific antigens of Schistosoma haematobium

Of the surface antigens identified by radio-iodination, two-dimensional gel analyses showed no similarities between those of Schistosoma haematobium and Schistosoma mansoni, thus providing a basis for the species specificity of these antigens described previously (Simpson, Knight, Hagan, Hodgson, Wilkins & Smithers (1985) Parasitology 90, 499-508). The surface antigens of S. haematobium were glycosylated and comprised an acidic polypeptide of Mr 17,000 as well as a complex set of polypeptides of approximate pI 6-7, which resolved in the Mr range 20,000-30,000. At least one of the lower Mr forms of this complex is also present in the adult worm. Limited cross-reaction was observed with S. mansoni infection sera and this may be due to a shared carbohydrate epitope. In contrast, extensive cross-reaction was observed using sera from mice immunized with S. bovis. This pattern parallels the species-specificity of vaccine-induced immunity. Extensive cross-reaction was also observed within cell-free translation products of m-RNA from adult worms of S. haematobium and S. mansoni by use of heterologous human infection sera. The few antigens which were species-specific may represent surface antigens.