An explanation of the protective effects of LDV infection on GVHD would thus be that massive viral replication, which peaks within the first 20 h after infection, induces strong viral RNA‐mediated activation of TLR7 which in turn elicits a strong but very transient production of type 1 IFN which affects antigen presentation by cDC and partly T cell alloresponsiveness. The gene discussed is TLR7; the disease is infection.