Expression and Characterization of Single-chain Fv-Fc Fusion Protein
against Human P185erbB2

XIE Zhi-Gang, GUO Ning*, SHI Ming, FENG Jian-Nan, YU Ming, SUN Ying-Xun, SHEN Bei-Fen

( Institute of Basic Medical Sciences, Academy of Military Medical Sciences, Beijing 100850, China )

Abstract In order to increase therapeutic effects and decrease immunogenicity of mouse McAb, the single-chain Fv (scFv) created by fusing the light and heavy chain variable region genes of anti-human P185erbB2 McAb was conjugated to the Fc gene of human IgG₁ to construct a scFv-Fc fusion gene. The scFv-Fc fusion gene was cloned into the expression vector pCIDN. The scFv-Fc fusion protein was synthesized as secreted two-chain molecules in CHO cells, and purified by affinity chromatography on recombinant protein A. A special 185 kD P185^erbB2 protein was immunoprecipitated by the scFv-Fc fusion protein. The fluorescence-activated cell sorting (FACS) using SK-BR-3 cells as the target indicated that the fusion protein could bind to the extracellular domain of P185^erbB2. The affinity of the scFv-Fc fusion protein, determined by ELISA, was K=7.5´10^-10 (mol/L)^-1. This work laid basis for further studies on the anti-P185^erbB2 scFv-Fc fusion protein.

Key words Her2/neu; scFv; fusion protein

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