Here we demonstrate a novel homogeneous one-step immunoassay, utilizing a pair of recombinant antibody antigen-binding fragments (Fab), that is specific for HT-2 toxin and has a positive readout. Advantages over the conventional competitive immunoassay formats such as enzyme-linked immunosorbent assay (ELISA) are the specificity, speed, and simplicity of the assay. Recombinant antibody HT2-10 Fab recognizing both HT-2 and T-2 toxins was developed from a phage display antibody library containing 6 * 107 different antibody clones. Specificity of the immunoassay was introduced by an anti-immune complex (IC) antibody binding the primary antibody-HT-2 toxin complex. When the noncompetitive immune complex assay was compared to the traditional competitive assay, an over 10-fold improvement in sensitivity was observed. Although the HT2-10 antibody has 100% cross-reactivity for HT-2 and T-2 toxins, the immune complex assay is highly specific for HT-2 alone. The assay performance with real samples was evaluated using naturally contaminated wheat reference material. The half-maximal effective concentration (EC50) value of the time-resolved fluorescence resonance energy transfer (TR-FRET) assay was 9.6 ng/mL, and the limit of detection (LOD) was 0.38 ng/mL (19 µg/kg). The labeled antibodies can be predried to the assay vials, e.g., microtiter plate wells, and readout is ready in 10 min after the sample application.
Arola, H. O., Tullila, A., Kiljunen, H., Campbell, K., Siitari, H., & Nevanen, T. K. (2016). Specific Noncompetitive Immunoassay for HT-2 Mycotoxin Detection. Analytical Chemistry, 88(4), 2446-2452. https://doi.org/10.1021/acs.analchem.5b04591