FIG. 4.

The inner nuclear membrane and the perinuclear space early in infection at an MOI of 1 (A and B) or 10 (C to G). (A) At the left is a capsid close to completion of budding at the inner nuclear membrane containing a dense envelope that is in close apposition to the outer nuclear membrane (o). At the right is a capsid with about three-fourths of the entire envelope acting as part of the outer nuclear membrane. The tegument is only present between the capsid and the membrane, which is turned almost 180° at one side. This process is described in the legend to Fig. 5. (B) Virion with a dense envelope in the perinuclear space that continues into RER cisterna. (C) Initial phase of a budding capsid at the inner nuclear membrane. Slight thickening of the nuclear leaflet and the course of the membrane underneath the capsid are demonstrated because of underfocusing. (D) Intermediate phase of budding with distinct thickening of the inner nuclear membrane that is sharply bent at one side. Some tegument is deposited around the capsid. To form an enveloped particle, the membrane must be pulled into the nucleus behind the capsid for fusion. (E) Virion within the perinuclear space, probably shortly after budding was completed because of the large indentation of the inner nuclear membrane. (F) Virion within the perinuclear space with a dense layer at the envelope that is in close apposition to both the inner and the outer nuclear membrane. (G) Virion within a cisterna contiguous to the perinuclear space, implying an intracisternal transport. Bars, 100 nm.