IRF protein expression after exposure to HIV. Day 6 MDDCs were treated with HIV-1_BaL (MOI, 3) or mock-treated for 6-120 hours. (A) IRF-1 intracellular expression levels were determined by flow cytometry; the isotype control is shown as filled curve, mock-treated cells are shown with a solid line and HIV-1–treated cells are shown with a broken line. (B) The percentage of HIV-1–infected cells was determined by flow cytometry with the use of a PE-conjugated p24 antibody and (C) peak IRF-1 expression was determined in p24⁻ cells and p24⁺ cells separately (means of 5 experiments shown with standard error bars). (D) IRF-1 expression was also determined by Western blot. (E) Panels A to C were repeated for IRF2, IRF-7, and IRF-8. Representative data are shown from 1 of 3 experiments.