IRFs and NF-κB directly bind the promoters of IFN-λ genes. PH5CH8 cells were stimulated with poly(I:C) (A and C) or infected with JFH-1 (B and D) for the indicated lengths of time. Chromatin was immunoprecipitated with anti-IRF-3, anti-IRF-7, anti-NF-κB antibody or control normal rabbit IgG. Purified ChIP and input DNA were analyzed by real-time quantitative PCR. The amount of ChIP DNA was normalized to that of input DNA. The mean value of control antibody before stimulation was arbitrarily defined as 1. Data are the mean ± SD of triplicate data points from a representative of five independent experiments. Statistical significance (p<0.01) is relative to IgG.