In immune-competent syngeneic hosts, intratumoural injection of 108 TCID50 VSV-GP-Luc resulted in comparable tumour-selective bioluminescence signals in parental LLC1 and LLC1-IFNAR1−/− tumours at 24 h post infection, indicative of similar first-round activity independent of the IFNAR status in the tumour. The gene discussed is IFNAR1; the disease is infection.