pDC IFN-I production has been shown to be tightly regulated in vivo during several viral infections, with a sharp peak confined to less than 24 h, and restricted to a small proportion of the cell population in mice during infections with NDV [96], MCMV [81] or LCMV [88] and in macaques during the acute phase of SIV infection [98]. This evidence concerns the gene PDC and infection.