APPLIED GENETICS AND MOLECULAR BIOTECHNOLOGY Construction of helper plasmid-mediated dual-display phage for autoantibody screening in serum

Abstract M13 filamentous bacteriophage has been used in displaying disease-specific antibodies, biomarkers, and pep-tides. One of the major drawbacks of using phage in diagnos-tic assays is the aspecific adsorption of proteins leading to a high background signal and decreasing sensitivity. To deal with this, we developed a genetically pure, exchangeable dual-display phage system in which biomarkers and streptavidin-binding protein (SBP) are displayed at opposite ends of the phage. This approach allows for sample purifica-tion, using streptavidin-coated magnetic beads resulting in a higher sensitivity of signal detection assays. Our dual-display cassette system approach also allows for easy exchange of both the anchor protein (SBP) and the displayed biomarker. The presented principle is applied for the detection of anti-body reactivity against UH-RA.21 which is a good candidate biomarker for rheumatoid arthritis (RA). The applicability of dual-display phage preparation using a helper plasmid system is demonstrated, and its increased sensitivity in phage ELISA assays using patient serum samples is shown