FIG. 4.

WNV SVPs produced in human cells and containing native glycosylation patterns bind selectively to cells expressing DC-SIGNR. (A) Binding of WNV SVPs to K562 cells. The indicated cell lines were incubated with medium only (filled area) or with NY99-6480 SVPs (6 nM E protein). SVPs were produced in 293T cells under standard conditions (solid lines) to produce particles with native glycosylation patterns or in the presence of the Golgi mannosidase inhibitor 1-deoxymannojirimycin (dashed lines) to increase the incorporation of high-mannose N-linked glycans. Bound SVPs were detected by staining with anti-WNV MAb 4E1-647. (B) K562-SIGNR cells (circles) were incubated with serial twofold dilutions of SVPs produced under standard conditions and processed for FACS as described for panel A. The geometric mean 4E1-647 fluorescence was calculated at each concentration of SVPs, and the background fluorescence of cells incubated in the absence of SVPs was subtracted from each value. A one-site binding curve was fit to these data and is shown as a solid line, with the dissociation constant (Kd) indicated. For reference, the background-subtracted binding to K562 control cells (diamond) is shown at the highest SVP input.