Second, the vast majority of IFN-I expressing cells in vivo in the spleen of infected mice were demonstrated to be pDCs, using intracellular staining with specific antibodies on cell suspensions or tissue sections at 30–36 hours post-infection [43] or YFP-IFNb reporter knockin mice at 12–24 hours post-infection [44]. The gene discussed is IFNB1; the disease is infection.