In the early phase of infection, plasmacytoid dendritic cells (pDCs) serve as the predominant IFN-I producers, sensing viral RNA through Toll-like receptor 7/8 (TLR7/8) and activating interferon regulatory factor (IRF)–mediated pathways to secrete large amounts of IFN-α and IFN-β (31, 32). Here, TLR7 is linked to infection.