For example, viral infection and poly(I:C) treatment activate the expression of the ISG15 of Atlantic cod [28], [29], [31], Atlantic salmon [27], [32], black rockfish [21], channel catfish [23], crucian carp [26], and Japanese flounder [25], while bacterial challenge activates ISG15 expression in Atlantic cod [25], goldfish [22], and red drum [30]. The gene discussed is ISG15; the disease is viral infectious disease.