Figure 2. Distribution of core particles in CsCl density gradient centrifugation analysis in 0.25 M histidine, 1 M MgCl2, 1mM DTT solution. (a) Aliquots were analysed by 7.5 % SDS-PAGE and stained with silver. (b) Aliquots were analysed by 1 % agarose gel electrophoresis and stained with 0.5 ug/ml ethidium bromide and visualised under UV light. Core particles were identified in fractions 6 to 8. Purified virus was loaded in the V lane as a marker.