Abstract: 　Objective To obtain single chain variable fragment(ScFv) against the circulating antigen(CAg) from Schistosoma japonicum(Sj). Methods Metabolic antigen of adult worm of Sj (Sj-MAg) was used in the panning of phage library against Schistosoma japonicum. The activity of Sj-MAg-binding phage clones was assayed by ELISA. The specificity of expression products of the positive clones was analyzed by ELISA, SDS-PAGE and Western blotting. Results Seventy-two randomly selected clones were tested for the presence of anti-Sj-MAg ScFvs, 6 clones showed positive. The specificity of these 6 clones was confirmed by binding them to antigens of other four trematodes. Two clones (B04,C24) were found to bind to Sj-MAg but not to any of the antigens of other four trematodes and their expression products were about 31kDa in size. Conclusion ScFv antibodies against the circulating antigens from Schistosoma japonicum Sj-MAg can be selected and manufactured from the antibody library.

Key words: Schistosoma japonicum, phage display antibody library, screening, identification