FIG. 5.

EB binds to HA. (A) Increasing concentrations of rHA (Vietnam/1203) were incubated with microtiter plates coated with EB (▪) or EBX (□) and washed, and binding was determined by enzyme-linked immunosorbent assay. Relative binding (n-fold) over nonspecific binding to BSA was determined by recombinant HA in wells that had been precoated with blocking buffer alone. All samples were tested in triplicate, and results are representative of at least three separate experiments. *, statistical significance (P < 0.01). (B) Competition of HA binding to EB was accomplished by adding a 1:1 molar ratio of free HA immediately prior to addition to a well containing immobilized EB or BSA. Data are expressed as relative absorbances and are presented as the mean values ± standard errors of A_{405 nm}/A₆₀₅ (n = 3). *, statistical significance (P < 0.01).