E2 pretreatment is necessary for the antiviral response down-regulation in DCs. (A) Measurement of IFNα/β and IP-10 levels by ELISA. E2 (10 μg/mL) pretreatment kinetic (0, 2, 6, 12, 24 hours) of DCs later infected for 9 hours with NDV-B1 in the presence of E2. Data are presented as mean plus or minus SD from 4 independent experiments. *P < .05 versus NDV-B1–infected DCs. (B) Measurement of IFNα/β and IP-10 by ELISA. DCs pretreated with 10 μg/mL E2 and infected for 9 hours without E2 in the medium (E2 pretreatment only) or DCs with no E2 pretreatment but infected in the presence of E2 for 9 hours with NDV-B1 (E2 only during infection). Data are presented as mean plus or minus SD from 4 independent experiments. *P < .05 versus NDV-B1–infected cells. (C) Type I IFN and IFN-responsive gene expression measured by qRT-PCR. DCs pretreated for 24 hours and infected for 9 hours with NDV-B1 in the presence of E2 (E2 pretreatment) and DCs without E2 pretreatment infected with NDV-B1 in the presence of E2 (E2 only during infection). Data are presented as mean plus or minus SD from 4 independent experiments. **P < .001 or *P < .05 versus NDV-B1–infected DCs.