Interestingly, MHV-A59 stimulated TNF production in Smurf1−/− BMDMs as early as 12 h post-infection, and the levels of TNF produced by Smurf1−/− BMDMs at 48 and 72 h post-infection were five times higher than those in MHV-A59-infected wild-type BMDMs (Figure 1a). This evidence concerns the gene TNF and infection.