Abstract: 　AIM: To obtain a large amount of purified 22.6 kDa antigen of Schistosoma japonicum ( Sj 22.6) in large quantity.METHODS: The sequence of the gene fragment encoding Sj 22.6 was reformed by PCR and subcloned into plasmid vector pGEX-1λT that coded for the 26 kDa GST antigen of Schistosoma japonicum ( Sj 26 GST). The recombinant plasmid was transformed into E.coli TG 2 and then the positive recombinant clone was expressed by induction with IPTG. RESULTS: The recombinant Sj 22.6/ Sj 26 GST fusion protein was expressed in 5.1% of total bacterial protein and was easy to be purified with glutathione sepharose 4B. Moreover, the purified recombinant Sj 22.6 antigen could be cut off easily from the fusion protein with thrombin and had high immunogenicity. CONCLUSION: The purified recombinant Sj 22.6 protein and Sj 22.6/ Sj 26 GST fusion protein had the same immunological activity as the native Sj 22.6 kDa protein .

Key words: Schistosoma japonicum, 22.6kDa antigen, recombinant antigen, fusion expression