ISG15 and infection: For our studies on NSDV and its effects on host ISGylation during infection we made use of the fact that ISG15ylation can also be generated by transfecting expression constructs for ISG15 along with plasmids encoding the core components of the ISG15 conjugation system, the E1 activating protein (mUBE1L), E2 conjugating protein (UbcM8) and E3 ligase (mHerc6) into cells in the absence of IFN [39].