Sedimentation coefficient of African swine fever virus

The sedimentation coefficient of the infective unit of African swine fever in tissue culture harvest fluids was measured in a preparative ultracentrifuge. The boundary locator method used also permitted making an estimate of heterogeneity. The sedimentation coefficient ranged from 3,000 to 8,000 Svedberg units, representing many classes of infective particles. Electron microscopy on culture fluids from infected cells showed many kinds of virus-containing units. Sucrose-CsCl gradient centrifugation was used to concentrate and to purify (partly) African swine fever virus for analytical ultracentrifugation. The optical patterns of the physical particles revealed a range of coefficients from 1,800 to 3,200 Svedberg units in tris-buffered saline solution at 20 C and buoyant densities from 1.19 to 1.24 g/ml in CsCl. The disparity of these values from those obtained by preparative ultracentrifugation indicates a change in the virus structure or a selection of viral populations on purification (or both).