Schistosoma bovis is a ruminant pathogen that is poorly known at a molecular level. With an aim of identifying the parasite proteins involved in host-parasite interplay, we studied two protein extracts that contain, respectively, the proteins excreted/secreted by the adult worm (ES) and the tegumental proteins exposed to the host (TG). The 2-DE, 2-D immunoblot and MS were employed to separate and identify the antigenic proteins and the most abundant non-antigenic proteins in each extract. There were some 400 and 600 spots detected in the ES and the TG extracts, respectively. Ninety-six spots were subjected to MS analysis and 64 of them were identified. Overall, we identified 18 S. bovis proteins located at the host-parasite interface, 16 of which have not been identified previously in this parasite, and one of which -lysozyme- has never been reported in a Schistosoma species. Of the proteins identified, at least 4 can counteract host defence mechanisms. The other proteins are also likely to play some role in the host-parasite relationships. Therefore, studies in grater depth on all these proteins will provide a better understanding of how this parasite interacts with its host and new strategies for anti-schistosome drug or vaccine design.

Schistosoma bovis is a ruminant haematic parasite that lives for years in the mesenteric vessels of the host. The aim of this work was to investigate the ability of adult S. bovis worms to interact with plasminogen, a central component in the host fibrinolytic system. Confocal microscopy analysis revealed that plasminogen bound to the tegument surface of the male-but not female-S. bovis worms and that this binding was strongly dependent on lysine residues. It was also observed that a protein extract of the worm tegument (TG) had the capacity to generate plasmin and to enhance the plasmin generation by the tissue-type plasminogen activator. Proteomic analysis of the TG extract identified 10 plasminogen-binding proteins, among which the major ones were enolase, glyceraldehyde-3-phosphate dehydrogenase and actin. This study represents the first report about the binding of plasminogen to Schistosoma sp. proteins.

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Schistosoma bovis is a parasite of wild and domestic ruminants that is broadly distributed throughout many tropical and temperate regions of the old world. S. bovis causes severe health problems and significant economic losses in livestock, but in contrast to human schistosomes, S. bovis has been little investigated at a molecular level. Since schistosome glycans and glycoproteins can play important roles in the host-parasite interplay, the aims of the present work were: (i) to characterize the glycans expressed by adult S. bovis worms on their excreted/secreted (ES) and tegumental (TG) glycoproteins and (ii) to identify their carrier protein backbones by mass spectrometry. Using a panel of lectins and monoclonal and polyclonal anti-glycan antibodies, we observed: (i) the absence of sialic acid in S. bovis; (ii) the presence of complex-type N-glycans and LDN antennae on ES glycoproteins; (iii) the presence of glycans containing the Fucalpha1-2Galbeta motif in many TG glycoproteins, and (iv) the presence of glycans containing the Fucalpha1-3GlcNAc motif on many ES and TG glycoproteins but, simultaneously, the absence of the F-LDN(-F) glycans from both the ES and TG glycoproteins. Interestingly, we also found the Lewis(X) and Lewis(Y) antigens co-expressed on several TG isoforms of ATP:guanidino kinase and glyceraldehyde-3-phosphate dehydrogenase. Finally, by ELISA we observed the presence of antibodies against Lewis(X), Lewis(Y) and F-LDN(-F) in the sera of sheep experimentally infected with S. bovis.