ISG15 and viral infectious disease: Consistent with results obtained from the virus-infected HINAE cells, until 6 h after viral infection, the expression of ISG15 (Fig 6D) and Mx (Fig 6E) was down-regulated in the kidney, spleen, and liver of rVHSV-P-infected fish, whereas their expression was up-regulated in rVHSV-wild-infected fish.