Plays a role in the escape of host innate immune response by promoting the degradation of host EIF2AK2/PKR and inhibiting host transcription (PubMed:19751406, PubMed:19211744, PubMed:19197350). Cytoplasmic NSs interacts with host FBXW11 to degrade PKR whereas nuclear pool binds to host FBXO3 to target TFIIH subunit GTF2H1 for proteasomal degradation with the help of the linker protein SKP1 (PubMed:19211744, PubMed:21543505, PubMed:23063407, PubMed:26837067). Removes FBXO3 isoform 1 from the nucleus (PubMed:24403578). Forms nuclear amyloid-like filaments of about 12 nm in width that may sequester NSs binding partners, causing cell cycle arrest (PubMed:10233964, PubMed:28915104, PubMed:32612175). Also aggragates in the cytosol as short fibrils late after host cell infection (PubMed:32612175). Plays a role in cell morphology and/or motility, reduction of lamellipodia, cell spreading, and dissolution of adherens junctions (PubMed:33087469). Multimerizes; forms 0.5-1 mm thick proteinaceous filaments in the nucleus (PubMed:28915104, PubMed:10233964). Interacts (via omegaXaV motif) with host FBXW11; this interaction is important for EIF2AK2/PKR degradation (PubMed:21543505, PubMed:26837067). Interacts (via omegaXaV motif) with host GTF2H1 (PubMed:25918396). Interacts with the host E3 ubiquitin ligase component FBXO3; this interaction is important for GTF2H1 degradation (PubMed:24403578). The C-terminus disordered region is involved in multimerization, filament formation, but not nuclear localization (PubMed:10233964). OmegaXaV motif is required for both nuclear filament formation and degradation of host GTF2H1 (PubMed:25918396). This motif also mediates FBXW11 binding (PubMed:26837067). Phosphorylated. Belongs to the phlebovirus NS-S protein family.