TYK2 and diabetes mellitus: These observations, taken together, suggest that enhanced production of IFN in Tyk2 KO mice was induced by strong stimulation for the innate immune system to produce IFN, due to extensive proliferation of EMC-D virus (Fig. 2c), and also indicate that the increased IFN-α in Tyk2 KO mice did not possess any biological significance to destroy β-cells or to resist against virus-induced diabetes.