[Isolation of the core of Dane particles from donor blood]

Ultracentrifugation in a flow rotor was used for partial purification and concentration of Dane particles from the plasma of donors, carriers of HBsAg. Subsequent purification was achieved by centrifugation in sucrose and cesium chloride density gradients. The iodinized inner component of Dane particles formed a peak in the zone of density typical of HBsAg localization. The specificity of the antigen was confirmed by the radioimmunologic method.