Intriguingly, the adoptive transfer of TLR7-competent pDCs to TLR7−/− mice in early-life is sufficient to reconstitute the antiviral response, as highlighted by the restoration of type I and III IFN production and accelerated viral clearance, suggesting that TLR7 signalling in pDCs is critical for protection against severe bronchiolitis. Here, TLR7 is linked to bronchiolitis.