FIG. 5.

2G12 and cyanovirin do not block gp120 binding to DC-SIGN. (A) Either 2G12 or cyanovirin (CVN) was preincubated with gp120-Fc at the indicated final concentrations before the gp120-Fc was placed onto BC7-DC-SIGN⁺ cells. The MFI obtained by gp120-Fc binding in the presence of 2G12 or cyanovirin was normalized to the MFI obtained in the absence of these agents. In all cases, the background was substracted by using the MFI obtained from human IgG staining alone. 2G12 and cyanovirin inhibition was repeated four and three times, respectively. The results are shown as means (± the standard deviation). (B) gp120-Fc binding (with or without cyanovirin) was performed on untreated BC7-DC-SIGN⁺ cells or on cells treated overnight with 10 μg of tunicamycin/ml. Note that cyanovirin enhanced gp120-Fc binding was reduced after tunicamycin treatment. (C) DC-SIGN-transfected 293T cells were pulsed with 5 ng of the indicated virus in the presence or absence of cyanovirin (0.2 to 20 μg/ml), 2G12 (2 to 200 μg/ml), mannan (500 μg/ml), or EGTA (10 mM). The amount of virus bound was determined by a p24 ELISA and normalized to the amount of p24 bound in the absence of any reagent (UnRx). Virus-binding experiments were performed twice in quadriplicates and once in duplicates with similar results.