FIG. 10.

Retention of UL20p within ER membranes causes a UL20-null defect in cytoplasmic virion envelopment. Vero (A, B, and C) or UL20-null complementing G5 (D) cells were infected with either parental wild-type KOS (A), control UL20p ER retention motif (B), or UL20p ER retention (C and D) virus. Cell monolayers were infected at an MOI of 5, incubated at 37°C for 20 h, and prepared for transmission electron microscopy. Nuclear (n), cytoplasmic (c), and extracellular (e) spaces are marked. Insets illustrate the inability of UL20p ER retention cytoplasmic capsids to attain an envelope and a transport vesicle.