Importantly, efficient depletion of PDCA-1+ cells including the entire pDC population (Fig. 6e and Supplementary Fig. 6) in 129 mice led to lower amounts of IFNα, a trend for less IFNβ and markedly decreased weight loss and morbidity while not affecting virus clearance (Figs 6b–e and 7a), demonstrating that morbidity was mediated by IFNαβ derived from pDCs or other cells upregulating PDCA-1 during infection. Here, IFNB1 is linked to infection.