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. 2015 Aug 25;10(8):e0135986. doi: 10.1371/journal.pone.0135986

Fig 3. Sensitivity of toxin detection by Vβ-immobilized beads in singleplex assays.

Fig 3

Each biotinylated, high-affinity Vβ protein (Vβ-SEA, Vβ-SEB, Vβ-TSST-1, Vβ-SpeA and Vβ-SpeC) immobilized on individual streptavidin-coated fluorescent beads was subjected to cognate, toxin binding titration (SEA, SEB, TSST-1, SpeA and SpeC respectively). Toxins captured by the Vβ-immobilized beads were detected with rabbit polyclonal anti-toxin antibodies (anti-SEA, anti-SEB, anti-TSST-1, anti-SEB and anti-SpeC respectively) followed by goat-anti rabbit IgG labeled with Alexa fluor 647. Flow cytometry histograms for each binding titration are shown, with fluorescence arising due to toxin binding on X-axis. Fluorescence in the absence of toxin is represented by gray (filled) trace on each histogram. Median fluorescence units from the histograms were used to generate binding curves, shown on the right. Red, dashed line indicates fluorescence in the absence of toxin. Data shown are representative of experiments performed in triplicate.