TLR7 and infection: While rapid type I IFN production in pDCs was observed following infection with mouse hepatitis virus (MHV), a betacoronavirus, its induction was abrogated in TLR7−/− or MyD88−/− MHV-infected mice, indicating that MHV-mediated type I IFN induction in pDCs was triggered via the TLR7/MyD88 pathway.