Figure 3. G_M1 ganglioside ELISA demonstrates functional receptor binding by the TcpF-A2-CTB chimera and CTB.

Several dilutions from stock solutions containing equimolar amounts of TcpF chimera, CTB, or TcpF were loaded onto ELISA plates coated with G_M1 ganglioside and serially diluted. Plates were probed with either rabbit anti-CTB (A) or TcpF antibody (B) followed by secondary probing with HRP-goat anti-rabbit IgG. Plates were read at OD₄₉₀ and optical densities were recorded. As controls duplicate antigen samples were assayed on empty plates (−G_M1) to demonstrate that CTB binding to immobilized G_M1 ganglioside is required to generate a signal in this assay.