ISG15 and parasitic infectious disease: Validation of gene expression differences was obtained by qRT-PCR for several ISG genes (MX1, OAS1Y, ISG15, RSAD2 [Viperin], IFI6, IFI44 and HERC5), and a number of ISG genes (HERC6, ISG15, IFI6, IFI44, IFIH1, IFI35, MX1, MX2, OAS2 and ZBP1) were identified as modulated by parasite infection, supporting the previous report on ISG15 [20].