Growth, purification and characterization of Semliki Forest virus in Ehrlich ascites tumor cell suspensions

The growth of Semliki Forest Virus (SFV) in suspension cultures of Ehrlich Ascites (EA) cells and its purification is described. Large volumes of virus material were concentrated by filtration with DIAFLO XM-300 membrane and precipitation with ammonium sulfate. A combination of protamine sulfate treatment, centrifugation of the virus onto a 50 per cent sucrose cushion, and sedimentation through a 5--30 per cent sucrose density gradient was employed. The purified virus particles were homogeneous as revealed by electron microscopy, by moving boundary electrophoresis, and by polyacrylamide gel electrophoresis. Virus suspensions containing 1 mg/ml of protein had a hemagglutinin titer of 1:12,000 when measured with 0.25 per cent goose red blood cells.