Intact IFN-γ/LPS signaling pathways in HHV-6–pretreated Mϕs. (A) Mϕs were incubated for 17 hours with HHV-6A (bold line) or mock infected (dashed line) and 48 hours later analyzed for CD14 levels by flow cytometry. Thin line indicates negative control. (B) Mϕs were pretreated or not with HHV-6A and then stimulated with IFN-γ and LPS as described in “Materials and methods.” After 3 hours of stimulation, Mϕs were harvested and analyzed for IL-1β mRNA levels by RPA. The data (mean from 6 donors ± SD) are shown as induction percentages, with the positive control set as 100%. (C) U937 cells were treated for 17 hours with HHV-6 GS (solid line) or mock infected (dashed line) and then analyzed for IFN-γRα and IFN-γRβ levels by flow cytometry. (D) Mϕs were isolated and treated with HHV-6A or left uninfected. After 17 hours, the cells were treated with IFN-γ for 30 minutes, after which they were harvested and analyzed for STAT-1 and phosphorylated STAT-1 levels.