Studies on Sendai Virus Cell Fusion Factor∗

Summary Induction of high levels of cell fusion by UV inactivated Sendai virus depends both on the virus preparation and the types of cells being fused. Studies on the optimal UV dose reveal a biphasic effect on the viral cell fusion factor (CFF). Other studies show that the CFF is very labile, is separate from both the hemagglutinin and the virion itself, and, therefore, is partially lost by the usual methods of viral concentration. Optimal conditions for inducing cell fusion by Sendai virus are described.