EM (A), and immuno-EM (B) analyses of Ad5R7Δknob-infected 293 cells at 48 h pi.

<p>In panel (A), an area of nucleoplasm shows small and twinned protein crystals seen in longitudinal, oblique and cross-sections. Virions are seen dispersed in the neighbourhood. Epon-embedded specimens. In panel (B), is shown a model of the crystal lattice derived from data obtained from as in (A). In panel (C), a section of metacrylate-embedded specimen was reacted with rabbit anti-penton base antibody followed by 10-nm colloidal gold-labeled anti-rabbit IgG goat antibody. Note the accumulation of gold-labeling in the protein crystalline inclusions. Some gold grains are also seen associated with virion clusters.