Separation of B and C Type Virions by Centrifugation in Gentle Density Gradients

Murine type B particles were separated from type C (Rauscher leukemia virus) by means of gentle (low-increment rate) density gradients. The best separation was obtained when the density ranged from 1.13 to 1.20 g/cm(3) when sucrose was used and from 1.12 to 1.28 g/cm(3) with CsCl. The buoyant densities of the B and C particle bands in sucrose were 1.18 and 1.16 g/cm(3), respectively. The CsCl gradient gave a better separation with the B particles banding at a density of 1.20 g/cm(3) and with the C particle density little different from its value in sucrose.