Figure 2.

General workflow for the purification of a herpesvirus. Extracellular virions are purified using centrifugation on density gradient, sometimes preceded by concentration on a sucrose cushion. As the purity is of major importance, electron microscopy observation is usually performed to confirm the absence of cell-derived organelles or membrane debris. The proteolysis of partially purified virions is often performed to remove contaminating proteins (dashed line, see also Figure 3).