r-Sm14 - pRSETA efficacy in experimental animals

Previous studies carried out with Sm14 in experimental vaccination against Schistosoma. mansoni or Fasciola hepatica infections were performed with re combinant Sm14 (rSm14)produced in Escherichia coli by the pGEMEX system (Pr omega). The rSm14 was expressed as a 40 kDa fusion protein with the major b acteriophage T7 capsid protein. Vaccination experiments with this rSm14 in animal models resulted in consistent high protective activity against S. ma nsoni cercariae challenge and enabled rSm14 to be included among the vaccin e antigens endorsed by the World Health Organization for phase I/II clinica l trials. Since the preparation of pGEMEX based rSm14 is time consuming and results in low yield for large scale production, we have tested other E. c oli expression systems which would be more suitable for scale up and downst ream processing. We expressed two different 6XHis-tagged Sm14 fusion protei ns in a T7 promoter based plasmids. The 6XUis-tagfusions allowed rapid puri fication of the recombinant proteins through a Ni+2-charged resin. The resu lted recombinant 18 and 16 kDa. proteins were recognized by anti-Sm14 antib odies and also by antiserum against adult S. mansoni soluble secreted/excre ted proteins in Western-Blot. Both proteins were also protective against S. mansoni cercariae infection to the same extent as the rSm14 expressed by t he pGEMEX system.