Interaction of Sendai (HVJ) Virus with Human Erythrocytes: A Morphological Study of Haemolysis Cell Fusion

Wellcome Research Laboratories, Beckenham, Kent, England June D. Almeida Royal Postgraduate Medical School, London, England The morphology of Sendai virus envelope is described in detail. The interaction of the virus envelope and erythrocytes is examined by negative staining and ultrathin sectioning. In this morphological study haemolysis is seen to progress in the following sequence: attachment of virus to cell membrane; dissolution of cell membrane at the site of attachment; dissolution of spikes opposite the dissolved cell membrane; fusion of the innermost virus (nanogranular) layer with the cell membrane proper; extension of this fused area with annular formation and extrusion of the virus internal components into the lumen of the cell; finally integration of the virus envelope into the cell envelope and detachment of the spikes. This stage could then lead to haemolysis and fusion. Haemolysis could occur through breaks in the unstable virus part of the integrated membrane and cell fusion could occur when this area is stabilized. Cell fusion of two or more cells is achieved by bridging with interspersed virus envelopes. Received 16 November 1971; accepted 27 January 1972.