FIG 2.
DENV2 NS1 directly binds human vitronectin (VN). (A) Microtiter plates were coated with purified VN (100 nM), and increasing amounts of recombinant DENV2 NS1e were added. Bound NS1e was detected using an anti-NS1 polyclonal antibody. BSA was used as the negative control. Error bars indicate standard deviations for three independent experiments, and asterisks indicate significant differences from the control based on two-way ANOVA and the Bonferroni posttest. ***, P < 0.001. (B) Replicates (black solid lines) and 1:1 fitting (gray dashed lines) of the binding of recombinant DENV2 NS1e to immobilized VN as analyzed by surface plasmon resonance analysis. Increasing concentrations of NS1e (0.12 to 3.0 μM) were injected onto a VN-coated CM5 sensor chip. The amount of NS1 associated with VN was measured in response units (RU). (Inset) The equilibrium response units (Req) obtained for binding of NS1 to immobilized VN were plotted against the concentration of NS1e.