Copyright0 1980 by Academic Press, Inc. All rightsof reproduction in any form reserved 0014-4827/80/120361~~02.~/0 ~x~e~ime~taf Cell Research 130 (1980)361-369 THE INTERACTION BETWEEN SENDAI VIRUS AND CELL MEMBRANES A Quantitative Analysis of lz51-Sendai Virus Particles’ Association with Human Red Blood Ceils D. WOLF, I. KAHANA,’ S. NIRZ and A. LOYTER Deparfmenf of Biological Chemisfry, The Hebrew Universify of Jerusalem, insfifufe of Life Sciences, Jerusalem, Israel SUMMARY Intact Sendai virus particles were radiolabeled by the use of chlommine-T and Na 3251. The method described is rep~ucible, efficient and appropriate for the preparation of large quantities of biolo~~y active virus with relatively high specific activity. Gel eiect~pho~sis analysis of the radiolabeled virus revealed that approx. 50% of the total ‘9 incorporated in the virus are associated with the two viral envelope glycoproteins, while the remaining 50% are evenly distri- buted throughout the other viral polypeptides. The *a31-virus particles were used to study some of the kinetic parameters of the interaction between Sendai virus particles and human erythrocytes. Binding of virus particles at 4°C is irreversible, non-cooperative and exhibits a characteristic saturation curve. A maximum of 1-2~ 103virus particles bound per cell was derived from the saturation curve. Non-radioactive native virus particles as well as isolated glycophorin molecules competitively inhibit binding of the 12sI-virusparticles to human erythrocytes. Incubation at 37°C of the virus-erythrocyte complex resulted in the release of about 33 % of the bound virus to the surrounding medium. The fusogenic Sendai virus, which belongs to the paramyxovirus group [ 1,2], has been used extensively during the last few years to study different aspects of membrane- membrane interaction [3, 41. Binding of Sendai virus particles to cellular plasma membranesis selective and dependent upon the specific association between a specific viral envelope ~ycoprotein (hem~lutina- tion/neur~inidase protein, HN) and ex- posed cell membrane sialoglycoproteins or sialoglycolipids [3-51. Infection of cells by this virus necessitatesthe fusion of the viral envelope with the host cell membrane, re- sulting in the integration of the viral en- velope glycoproteins into the cell plasma membrane and to the intra-cytoplasmic in- 24-801808 jection of the viral nucleocapsid [4, 6f. A consequence of Sendai virus-cell fusion is the promotion of cell-cell fusion [6]. Ex- perimental evidence suggests that in addi- tion to the HN glycoprotein, a second viral envelope glycoprotein, the F protein (fusion protein) is a requisite for the fusion of virus envelope with the cell membrane and, therefore, for the induction of cell-cell fusion [3,7-91. Enveloped viruses are able to infect ani- mal cells also by other mechanisms. Elec- 1 Present address: Department of Biomembrane Re- search, Hadassah University Hospital, Jerusalem, Israel. * Present address: Roswell Park Memorial institute, N.Y. State Department of Health, Buffd~, NY 14203, USA. E.xp Cell Res I30 f1980)