The identification of affinity peptide ligands specific to the variable region ofhuman antibodies

Abstract

Of all potential biological therapeutics, monoclonal antibody (mAb)-based therapies are becoming the dominant focus of clinical research. In particular, smaller recombinant antibody fragments such as single-chain variable fragments (scFv) have become the subject of intense focus. However, an efficient affinity ligand for antibody fragment purification has not been developed. In the present study, we designed a consensus sequence for the human antibody heavy or light chain-variable regions (Fv) based on the antibody sequences available in the ImMunoGeneTics information system (IMGT), and synthesized these consensus sequences as template Fv antibodies. We then screened peptide ligands that specifically bind to the repertoire-derived human Fv consensus antibody using a 12-mer-peptide library expressed-phage display method. Subsequently, 1 peptide for the VH template and 8 peptides for the VK template were selected as the candidate ligands after 4 rounds of panning the phage display. Using peptide-bead-based immunoprecipitation, the code-4 and code-13 peptides showed recovery rates of the VH and VK templates that were 20-30% and 40-50%, respectively. Both peptides exhibited better recovery rates for trastuzumab scFv (approximately 40%). If it were possible to identify the best combination of VH and VK-binding peptides among the ligand peptides suitable for the human mAb Fv sequence, the result could be a promising purification tool that might greatly improve the cost efficiencies of the purification process.In recent years, advances in protein research have resulted in several monoclonal antibody (mAb) therapies for cancer, infections and immunological disorders, which have increasingly become the preferred choice out of the many available biological therapeutics. In the United States which is the largest market for mAb therapeutics worldwide, more than 20 mAbs have been approved for clinical use and over 200 mAb candidates are in the clinical pipeline (21,25). Monoclonal antibody therapeutics are playing an important role in the clinical field and recombinant antibodies are predicted to account for more than 30% of all revenues in the biopharmaceutical market (1,4,22

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