Abstract: Objective To clone and express Schistosoma japonicum （Sj） calcyphosine gene， and purify the exp-ressed protein. Method The encoding sequence selected from Sj cDNA library was amplified by PCR. After subcloned into prokaryotic expression vector pET-28a， the expressed protein was purified with His·Tag affinity chromatography. Western blotting was used to detect the immunogenicity. The structure and functions of the protein were analyzed by bioinformatics method， and the phylogenetic tree of the protein was drawn. Result The recombinant protein was specifically recognized by the Sj infected rabbit serum. The bioinformatics analysis showed 4 EF-hand domains. Besides， it was predicted that Sj calcyphosine contains two phosphorylation sites for protein kinase C， eight phosphorylation sites for casein kinase II and one N-myristoylation site. The Sj calcyphosine belonged to type-II calcyphosine. Conclusion The calcyphosine gene is a calsium-binding protein and might be a potential candidate for diagnosis， vaccine or drug target.

Key words: Schistosoma japonicum, Calcyphosine, Prokaryotic expression