FIGURE 4.

V_HH heterodimers in vitro toxin-neutralizing activity. To assess toxin-neutralizing activities of select V_HH heterodimers (F5/B7, D10/B7, E5/B7, G5/B7, and G5/B9) and compare them with their monomeric constituents and equimolar mixtures of those monomers, the V_HHs were tested in a Vero cell cytotoxicity assay, as described in the legend of Fig. 2. V_HHs (at indicated concentrations, nm) were mixed with ricin (10 ng/ml) and applied to Vero cells in triplicate. A–E show a single pair of monomeric V_HHs (open symbols) and their corresponding heterodimers (solid symbols). Each panel represents one heterodimer and its corresponding monomers, as indicated in the legends embedded within the graphs. Shown are representative experiments with error bars indicating S.D. All experiments were replicated at least three times.