SRSF1 and viral infectious disease: Finally, bimolecular fluorescence complementation (BiFC) images showed association of NS1 and SF2 in transfected cells and immunostaining of SF2 and NS1 proteins in the early hours of virus infection showed spots of NS1 and SF2 co-localization in the nucleus, further confirming interaction of these proteins (Supplementary Fig. 5c,d).