 Biotinylated, high-affinity Vβ proteins (Vβ-SEA, Vβ-SEB, Vβ-TSST-0, Vβ-SpeA and Vβ-SpeC) were immobilized on streptavidin-coated fluorescent beads (P00, P00, P0, P0 and P0 respectively, each having unique fluorescence in the FL-0 channel