The syndecan-Fc hybrid molecule blocks HSV infection. Vero cells (250,000 cells) were exposed to HSV-1-GFP or HSV-2-GFP (MOI of 0.1) together with control Fc, syndecan-1-Fc, heparinase-treated syndecan-1-Fc, or Δ3HS syndecan-1-Fc lacking HS chains (5 μg/ml). After 2 days, Vero cell infection was scored by FACS by quantifying the percentage of GFP+ cells. Data are expressed in percentage of GFP+ cells. The points are median values, and error bars represent standard errors of triplicates. The P values were calculated using a one-sided t test assuming equal variances. (B) The experiment is as described in the legend of Fig. 2B.