iNOS gene-deficient DBA/2 mice showed reductions in IL-1β and TNF-α mRNA expression in both macrophages and β-cells, β-cell apoptosis, and the incidence of VID, indicating that NO plays an important role in the activation of macrophages and apoptosis of β-cells in the model with infection by a low dose of EMCV-D [88]. Here, TNF is linked to infection.