FIG. 1.

(a) Relative binding affinity of MAb5 for TSST-1 and SEB by ELISA. MAb5 reacted strongly with TSST-1, with a relative binding affinity of 2.05 nM. MAb5 also reacted with SEB in a dose-dependent manner, with a relative binding affinity of 0.00216 nM (1,000-fold lower than for TSST-1). The IgG1 isotypic control MAb (63D3) did not bind to either TSST-1 or SEB. (b) Inhibition of maximum TSST-1 binding to a constant amount of MAb5 (10 μg/ml) by either TSST-1 or SEB. The dose of TSST-1 for 50% inhibition of maximum binding of TSST-1 to MAb5 was 0.041 μM. SEB was unable to inhibit TSST-1 binding to MAb5. The IgG1 isotype control did not bind to either TSST-1 or SEB.