Surface plasmon resonance analysis of FX-Ad interactions. AdCTL or AdKO1 was perfused over FX and FXI immobilized onto a CM5 sensor chip in 50 mM Tris (pH 7.4), 150 mM NaCl, 5 mM CaCl₂, and 0.005% Tween 20 at a flow rate of 20 μL/min at 25°C. Depicted are typical sensorgrams following injection of AdCTL (A) and AdKO1 (B) showing association with FX but not FXI, with undetectable dissociation of virus from FX following the end of the injection but ready dissociation upon injection of 3 mM EDTA. The differential sensorgrams, FXI signal subtracted from the FX signal (FX - FXI), showing the association of AdCTL (C) and AdKO1 (D) with FX at various concentrations (× 10¹¹ VP/mL) were superimposed, demonstrating the concentration dependence. The steady-state change in RU (δRU) was plotted against virus concentration (E), and affinity constants were determined by performing nonlinear regression fitting of the data (R²  values: AdCTL = 0.99 and AdKO1 = 0.99).