Quantitation of the various species of intracellular capsids. Electron micrographs of Vero cells infected for 24 h with WT or ΔUL16S virus (MOI, 1) were obtained, and the DNA-filled capsids were counted and classified as either free capsids (not near membranes), membrane-associated capsids, multicapsid virions (2 or more capsids fully wrapped with a single envelope), or mature virions (completely wrapped with a single capsid). Micrographs from 3 independent experiments were used, yielding a total of 1,008 WT capsids and 607 ΔUL16S capsids.