Abstract: 　Objective To construct single chain Fv (scFv) gene of anti idiotypic monoclonal antibody NP30 of Schistosoma japonicum . Methods The heavy and light chain variable region genes of anti idiotypic monoclonal antibody NP30 of Schistosoma japonicum were inserted into two corresponding sites of expression vector pTHA90,and a scFv gene was constructed with a short peptide (Gly 4Ser) 3 linker gene. The recombinants were determined by digesting with Xho I/ Spe I, Xba I/ Eco RI and Xho I/ Eco RI,and then were introduced into E.coli Top10. The antigen binding activity of expressed product was detected with ELISA. Results The recombinants were determined by digesting with endonucleases and expected bands were identified. The value of expressed scFv was 3 times higher than negative control by ELISA(OD 492 =1.06). Conclusion The scFv gene of anti idiotypic monoclonal antibody NP30 of Schistosoma japonicum was successfully cloned, and the expressed scFv fragment could interact specifically with antigen NP48.

Key words: Schistosoma japonicum, anti idiotypic monoclonal antibody, single chain Fv(scFv), cloning, expression