Because IRF-7 has previously been shown to act together with IRF-3 to induce later-phase production of high levels of type I IFN in fibroblasts during viral infections (35), we hypothesized that in macrophages, which produced higher levels of IFN-β compared with DCs, IRF-7, in addition to IRF-3, induces IFN-β production after LPS stimulation. This evidence concerns the gene IRF3 and viral infectious disease.