The DIs encompass genes that might affect several traits responsible for phenotypic difference between the marine and freshwater forms, including the well-known EDA gene responsible for body armor ([27],[41], DI IV-1), as well as genes likely to be important for adaptation to freshwater through their effects on osmoregulation, immunity, or morphology: Na+/K+ transporting ATPase (ATP1A1[42], DI I-1), neurotransmitter and hormone binding (SULT4A1[43], DI IV-4), and immunity response to viral infection (NLRC5[44], DI XIX-1). This evidence concerns the gene NLRC5 and viral infectious disease.