E2 inhibit DC maturation triggered by 5′ triphosphate viral RNA. MCF-7 cells were transfected with IFNβ promoter reporter construct driving firefly luciferase(A) alone or (B) along with a plasmid expressing RIG-I (top panel), RIG IN (bottom panel), or an empty plasmid. Cells were then pretreated or not with 10 μg/mL E2 and 24 hours later and infected with NDV-B1 (MOI = 0.5) for 6 to 8 hours (top panel) or just pretreated for 24 hours with E2 (bottom panel). The Relative Luciferase Units (RLUs) were measured 6 to 8 hours after NDV-B1 infection and RIG-IN transfection, respectively. (C) Cells were cotransfected with NDV genomic RNA (50 ng, 100 ng, 200 ng), treated or not with CIAP, or transected with irrelevant human mRNA (50 ng, 100 ng, 200 ng) along with IFNβ promoter reporter. As a control for the activation of the IFNβ promoter, cells were also infected with NDV-B1 for 6 hours. Cells pretreated or not with E2 were: (D) cotransfected with 100 ng viral RNA along with IFNβ promoter reporter for 6 to 8 hours or (E) transfected with viral RNA (50, 100, 200 ng) treated or not treated with CIAP. RIG-I expression was measured by RTqPCR 6 hours after infection. Results are presented as mean plus or minus SD and are representative of 3 experiments.