Abstract: AIM: To construct an eukaryotic expression system pcDNA3/ESG HeLa cell and explore
the possibility of whether the eggshell protein might be used as potential targets for vaccine
development. METHODS: The eggshell protein gene(ESG)was amplified using PCR technique and
inserted into vector pcDNA3 to construct recombinant vector pcDNA3/ESG. The expression of the
eggshell protein was performed in HeLa cell line.SDS PAGE,dot ELISA and Western blotting were
used to identify the antigenicity of the expressed product. RESULTS: The amplification of ESG (618) bp was achieved and high level expression of the eggshell protein was obtained in HeLa cells and the amount of total expressed products was up to 24.4%. Dot ELISA and Western blot analysis demonstrated that the expressed protein could be recognized by sera from rabbits infected with S.japonicum and from female worm-or egg-immunized rabbits. In addition, the expressed protein could specifically stimulate proliferative response of the immunized BALB/c mouse spleen cells, the transformation rate being up to 44.57%. CONCLUSION: The eukaryotic expression system pcDNA 3/ESG was successfully established and high level expression of the eggshell protein of S.japonicum was achieved in HeLa cell line. The expressed recombinant protein exhibited immunological activities.

Key words: Schistosoma japonicum, eggshell protein, cloning, expression