Nucleoprotein (N) is ADP-ribosylated. The modification is maintained both in the cell and in virions (Grunewald et al, 2018). Members of the protein mono-ADP-ribosyltransferase (PARP) enzyme family are thought to catalyze this reaction (Fehr et al. 2020).
NAD+ ADP-ribosyltransferase activity of PARPs [cytosol]