IRF1 and viral infectious disease: This simplified framework omits the role of many other transcription factors (TFs) (such as IRF1) that also contribute to IFN expression, but has general explanatory power; for instance, the constitutive expression of IRF7 by plasmacytoid dendritic cells (pDCs) explains why these cells secrete 1000-fold more IFNα than other cells, on a per-cell basis, during the early phases of viral infections.