Screening trematodes for novel intervention targets: a proteomic and immunological comparison of <i>Schistosoma haematobium</i>, <i>Schistosoma bovis</i> and <i>Echinostoma caproni</i>

With the current paucity of vaccine targets for parasitic diseases, particularly those in childhood, the aim of this study was to compare protein expression and immune cross-reactivity between the trematodes &lt;i&gt;Schistosoma haematobium&lt;/i&gt;, &lt;i&gt;S. bovis&lt;/i&gt; and &lt;i&gt;Echinostoma caproni&lt;/i&gt; in the hope of identifying novel intervention targets. Native adult parasite proteins were separated by 2-dimensional gel electrophoresis and identified through electrospray ionisation tandem mass spectrometry to produce a reference gel. Proteins from differential gel electrophoresis analyses of the three parasite proteomes were compared and screened against sera from hamsters infected with &lt;i&gt;S. haematobium&lt;/i&gt; and &lt;i&gt;E. caproni&lt;/i&gt; following 2-dimensional Western blotting. Differential protein expression between the three species was observed with circa 5% of proteins from &lt;i&gt;S. haematobium&lt;/i&gt; showing expression up-regulation compared to the other two species. There was 91% similarity between the proteomes of the two S &lt;i&gt;chistosoma&lt;/i&gt; species and 81% and 78.6% similarity between &lt;i&gt;S. haematobium&lt;/i&gt; and &lt;i&gt;S. bovis&lt;/i&gt; versus &lt;i&gt;E. caproni&lt;/i&gt;, respectively. Although there were some common cross-species antigens, species-species targets were revealed which, despite evolutionary homology, could be due to phenotypic plasticity arising from different host-parasite relationships. Nevertheless, this approach helps to identify novel intervention targets which could be used as broad-spectrum candidates for future use in human and veterinary vaccines