Objective   To express and identify the phage antibodies against circulating antigen ofClonorchis sinensis, (Cs-CAg).

  Methods   B05、C10 and E38 positive clones were incubated with IPTG respectively, Fab antibodies were observed by SDS-PA GE and Western blot. Moreover, Ag of Paragonimus westermani (Pw), Fasciola hepatica (Fh), Fasciolopsis buski (Fb), clonorchis sinensis (Cs), schistosoma japonicum (Sj) and Cs-CAg were separated in SDS-PA GE, then bound with B05、C10 and E38 phage antibodies respectively in Western blot.

  Results   By Western blot analysis of 3 positive clones, two molecular masses of 50kDa and 27kDa could be found under reducing condition in supernatant and lysed cell pellet of 3 positive clones. The former was an intact Fab molecular, the latter was heavy chain Fd fragment and light chain. The results of immunoblotting showed that both B05 and E38 could bind to Cs-MAg specifically, former at a molecular weight of 25kDa and latter at 16kDa respectively, both of them did not react with any other four trematode antigens. While C10 bound to not only Cs-MAg, but also Sj-Ag at a molecular weight of 38kDa, and did not react with any other three trematode antigens.

  Conclusion   Three positive clones can express the phage antibodies against clonorchis sinensis CAg.B05 and E38 can bind Cs-CAg specifically.