FIG. 4.

Models of the tomogram shown in Fig. 3. A. Thick slice through the center of the virion. The nucleocapsid shell (purple) and virion envelope (green) are modeled by computationally fitting surfaces to densities in the tomogram, while the ONM (blue), INM (green), and bridging rods (yellow) are modeled by manual tracing. The DNA within the core is not shown. B. Side view of the nucleocapsid surface (purple) and the attached bridging rods (yellow). The horizontal elongation of the rods is an artifact due to the limited tilt range of the tomogram. C and D. Cutaway views of the enveloping nucleocapsid shown as a surface-rendered model after manual tracing. The nucleoplasm is on the bottom and cytoplasm on the top. The near portion of the model has been cut away for illustration. The nucleocapsid (purple), bridging rods (yellow), virion envelope (green), INM (green), and ONM (blue) are shown. As only the surfaces were rendered, the nucleocapsid and nascent virion envelope appear as hollow shells in this cutaway view. Note that the virion envelope is more than twice as thick as the neighboring INM.