Inhibits post-transcriptional processing of cellular pre-mRNA, by binding and inhibiting two cellular proteins that are required for the 3'-end processing of cellular pre-mRNAs: the 30 kDa cleavage and polyadenylation specificity factor (CPSF4) and the poly(A)-binding protein 2 (PABPN1). This results in the accumulation of unprocessed 3' end pre-mRNAs which can't be exported from the nucleus.
In uninfected, transfected cells, NS1 is localized in the nucleus. Only in virus infected cells, the nuclear export signal is unveiled, and a fraction of NS1 is exported in the cytoplasm
has not yet been referenced specifically in any publications.