MAGPIX Assay for Influenza A Using Single Domain Antibodies

Single domain antibodies (sdAbs) provide versatile binding reagents that offer advantages over conventional antibodies for use in immunoassays. SdAbs consist of the ~15 kDa variable heavy domain from the heavy chain-only antibodies found in camelids and can be engineered for integration in a variety of immunoassay formats. The Luminex MAGPIX instrument is a high-throughput platform that uses color-coded MagPlex beads to enable multiplexed immunoassays and is relatively fast and simple. We developed a MagPlex bead-based assay for the detection of influenza A virus (IAV), using sdAbs against IAV nucleoprotein (NP). To provide sensitive detection, the sdAbs were formatted into bivalent constructs; and the capture reagent was tailored to provide oriented immobilization on the bead. Using the best capture and reporter pair, we achieved detection of recombinant NP down to 1 ng/mL. Finally, we demonstrated that the developed immunoassay showed promise in detecting IAV in clinical samples.