Proteomic analysis of the tegument and excretory-secretory products of adult Schistosoma bovis worms

Abstract

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.

Excretory/Secretory Proteome of the Adult Developmental Stage of Human Blood Fluke, Schistosoma japonicum

“…However, our study indicated it may be excreted or secreted into host serum (Table I); this result strongly argues against the possibility that SjFABP is unlikely to be accessible to the immune system (52). Furthermore the presence of FK506-binding protein in the adult worm ES proteome was also observed in Fasciola hepatica (29,30), S. bovis (33), and S. mansoni (34,35), suggesting that its secretion is conserved among trematodes. FABP from F. hepatica induces an immune response in mice that is protective to challenge infection with S. bovis cercariae (62), whereas FABP from S. mansoni induces immune protection against challenge with F. hepatica metacercariae and S. mansoni cercariae (62).…”

“…As shown by immunoblotting, there were fewer immune antigenic proteins in ES product than in whole worm protein extracts, which is contrary to the notion that ESPs are exposed to the host immune system and enriched in antigenic proteins. This was also true for the ES and tegument proteome of S. bovis adult worms (33). One explanation for this phenomenon is that the challenged sera contained antibodies against ES proteins from eggs or schistosomula but minimal antibodies against the adult worms.…”

“…Importantly this information can be expected to facilitate the discovery of vaccines and new therapeutic drug targets as well as new diagnostic reagents for schistosomiasis control. Proteomics approaches encompass the most efficient and powerful tools for identification of protein complexes and have been widely used to decipher the ES components of the filarial parasite Brugia malayi (19), Leishmania (Trypanosomatidae) (20), nematodes (21)(22)(23)(24)(25)(26), and Trematoda (27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37). For the genus Schistosoma, the ES compositions of S. mansoni have been identified in many developmental life stages, including sporocyst (34), cercaria (35,36), and egg (37) but have not been characterized in the adult worm.…”

Schistosomes—proteomics studies for potential novel vaccines and drug targets

“…Studies were also performed to explore the protein content of the tegument of the ruminant parasite S. bovis [50]. One of these studies used 2D immunoblots with infected sheep serum to identify the most antigenic proteins in the tegument preparation.…”

“…The spots from a parallel 2D electrophoresis corresponding to those regions identified in the 2D immunoblot were excised and 5 different proteins were determined by mass spectrometry. All of those proteins are soluble and include orthologs of S. mansoni vaccine candidates glutathione-S-transferase and GAPDH [50]. Considering that the approach that has been utilized shows a very limited recovery of integral membrane proteins, it is understandable that only soluble proteins have been sampled.…”