Modification of HVJ Envelopes Integrated in Fused Cell Membrane Structure during the Course of Cell Fusion

Abstract

The fate of HVJ envelopes fused with Ehrlich ascites tumor cells was examined. On culture at 37°, the hemadsorption (HA) activity of the cells, which depended on the fused envelopes, disappeared within 4 hrs without liberation of the viral hemagglutinins into the medium. The viral antigens detectable on whole surface of fused cells also disappeared on culture. During this period a specific projection developed on the fused cells. Development of this projection was maximal after 4 hrs, when viral antigens had accumulated on it like a "cap". On further incubation, the fused cells became HA-positive again for 6 hrs and viral antigens reappeared on the whole of the cell surfaces. These were due to new growth of viral glycoproteins in the cells.Both disappearance of HA and cap formation of viral antigens were dependent on temperature and pH. They occurred in cultures in Eagle's minimum essential medium with or without serum. In cultures in a buffered salt solution, decrease in the HA-activity was about 80 % of that in cultures in MEM, but the accumulation of viral antigens was very low. Sodium azide inhibited HA-disappearance and the cap formation. Monosaccharides had most effect and inhibited all these changes completely.