FIG. 4.

Apparent stages in the envelopment of VZV in the TGN of cells infected with intact (Ellen) VZV. (A) An unenveloped nucleocapsid makes contact with a specialized C-shaped cisterna of the TGN. Electron-dense material that resembles tegument accumulates between the nucleocapsid and the concave face of the wrapping cisterna. (B and C) The arms of the “C” of the wrapping cisterna extend toward one another, eliminating the space open to the cytosol and gradually enclosing more and more of the nucleocapsid. The electron-dense material remains adherent to the concave face of the wrapping cisterna. (D) The opening to the cytosol has been closed. Two membranes surround the nucleocapsid. The inner membrane has electron-dense tegument-like material adherent to it. The structure is interpreted to be a newly enveloped virion enclosed in a transport vesicle. The inner membrane is in contact with tegument and is derived from the concave face of the original C-shaped cisterna. The outer membrane, that of the transport vesicle, is derived from the convex face of the C-shaped cisterna. Bars, 150 nm.