[Isolation of nuclei from influenza virus infected chick fibroblast cells]

Three methods of nuclei isolation from influenza virus-infected chick fibroblast cells are characterized comparatively. The purity of the nuclear preparations was evaluated by hemagglutinin determination in them in hemagglutination test or hemagglutinin and membrane protein determination by polyacrylamide gel electrophoresis of labeled proteins. The purest nuclei were prepared by the method using citric acid--MgCl2--triton X-100.