IFI16 and infection: Using a FISH assay, they demonstrated that during HSV-1 (strain 17+) infection of U2OS cells (5 PFU/cell) containing transfected IFI16-EGFP construct, virion DNA colocalized only with full length IFI16-EGFP with intact NLS and not with mutated NLS-IFI16-EGFP that were localized in the cytoplasm.