A high-affinity recombinant antibody permits rapid and sensitive direct detection of myeloperoxidase

Over the past 10 years, a growing field of research supporting the value of myeloperoxidase (MPO) as a prognostic indicator in acute cardiac pathophysiologies has emerged. The availability of a rapid and disposable MPO detection platform would enable research clinicians to more readily assess MPO indications for guiding therapy and also facilitate clinicians at the patient interface to readily adopt MPO testing and potentially drive more informed prognoses. Here we describe the isolation of a high-affinity avian MPO-specific recombinant antibody panel using phage display. Rapid isolation of a suitable single-chain variable fragment (scFv) antibody was facilitated using a surface plasmon resonance (SPR)-based "off-rate ranking" screening process. The selected scFv was then successfully incorporated into a rapid, simple, and sensitive one-step lateral flow immunoassay (LFIA) for the detection of MPO. This "one-step" feature of the developed assay was made possible by the scFv's strong affinity for MPO, obviating the need for sandwich signal enhancement steps. The assay's rapid performance was also further enhanced by exploiting the intrinsic enzymatic properties of MPO in its final detection. Use of the optimized LFIA facilitated the sensitive detection of MPO in MPO-depleted serum within clinically relevant reference ranges.