514G3 antibody binds to WT SpA with specificity and picomolar affinity.

<p>A. Antigen binding profiles of 514G3 captured on an active flow cell on a Biacore 3000. The colored lines on the sensogram represent the recorded binding response signals at different antigen concentrations from 2-0nM, and the overlaid black lines represent the fitted curves. Binding of SpA to 514G3 was monitored in real time to obtain on (ka) and off (kd) rates. The equilibrium constant (K_D) was calculated from the observed Ka and Kd and found to be 46.7pM. B. A graph showing the relative binding of 514G3 to SpA, MabSelect and MabSelect SuRe ligands. The three different SpA domain variants were coated on the wells of an ELISA plate, and then probed with biotinylated 514G3 or VH3/IgG3-k isotype control at 4μg/ml, and detected with streptavidin-HRP. The graph shows OD at 450nm on the y-axis and the different SpA domain variants on the X-axis. The error bars show the standard deviation from three replicates.