[Production of an Anti-PIVKA-II Recombinant Single-Chain-Antibody in Escherichia Coli].

Protein induced by vitamin K absence or antagonist-II (PIVKA-II) is an abnormal prothrombin lacking gamma-carboxylation of the 10 glutamic-acid residues in the N-terminal region. PIVKA-II has been used as an effective biomarker of hepatocellular carcinoma (HCC) since the PIVKA-II level is not correlated with that of alpha-fetoprotein (AFP), which is another effective biomarker for HCC. Monoclonal antibodies for the clinical biomarker test are usually expensive because of their high production costs. Recently, many studies involving the expression of the recombinant globulin molecules in bacterial cells and plants have been con- ducted. These studies have enabled us to produce recombinant monoclonal antibodies at much lower costs. In this study, we first produced a hybridoma expressing a monoclonal antibody against PIVKA-II, and then we constructed and produced a single-chain fragment-variable antibody (scFv), created by the linking of variable regions of light- and heavy-chains of the PIVKA-II monoclonal antibody with a peptide linker of triplicated GGGGS. The scFv was expressed in E. coli and exhibited high specificity for PIVYKA-II binding, while its binding titer was low. [Review].