Schistosoma japonicum: efficient and rapid purification of the tetraspanin extracellular loop 2, a potential protective antigen against schistosomiasis in mammalian.

The extracellular loop 2 of a tetraspanin from Schistosoma japonicum (Sj-TSP-2) is homologous to Schistosoma mansoni TSP-2. In our initial study, Sj-TSP-2 is an identical antigen against schistosomiasis caused by S. japonicum. Through the pET32 vector system and nickel (Ni)-absorbed chelating Sepharose, Sj-TSP-2 was expressed and purified as a soluble fusion constructed with an N-terminal thioredoxin-His(6)-EK protease site tag (Trx-TSP-2). In phosphate buffer (PB) with a low concentration of imidazole, the Trx-TSP-2 fusion protein was efficiently cleaved by enterokinase (EK). Sj-TSP-2 was isolated and enriched using cobalt (Co)-absorbed chelating Sepharose and HiTrap SP column. Character of the protein was analyzed via animal experiments and then clinical trials. The purification approach yielded pure Sj-TSP-2, which will provide feasible advices for discovering vaccines against schistosomiasis.