Selection and Characterization of Human Serum Albumin-specific Porcine scFv Antibodies Using a Phage Display Library

Abstract

A new single-chain variable fragment (scFv) antibody library was generated and human serum albumin (HSA)-specific clones were characterized to investigate the usefulness of porcine antibodies. Phage libraries were developed from pigs immunized with the model antigen HSA. The library size was 1.5×10⁷ for kappa (V_L) and 1.4×10⁷ for lambda fragments. Eight HSA-specific clones from the kappa library and one clone from the lambda library were isolated using affinity selection. The binding specificity of these clones was confirmed using a phage enzyme-linked immunosorbent assay (ELISA). The scFvs were expressed in Escherichia coli and purified from the periplasm fraction for further investigation. Based on the results of ELISA and Western blot analysis, four scFv clones with high activity and high yield were selected and purified. The purified scFvs from four of the nine clones exhibited an approximate K _D of 10⁻⁸ M. This is the first report describing isolation of HSA-specific porcine scFv antibodies from an antibody phage library and characterization of their binding properties.