Membrane Assembly during the Infection Cycle of the Giant Mimivirus
Figure 2
Cisternae and vesicles apposing viral factories at the onset of capsid assembly.
A. 10 nm digital slice derived from a 280 nm-thick STEM tomogram of a 7.5-hour PI viral factory. The slice reveal cisternae (arrows) and clusters of ∼70 nm vesicles (arrowheads) at close vicinity to the viral factory (VF). B. Magnification of the delineated regions in (A). C. A different digital slice from the STEM tomogram shown in (A), with 3-dimensional surface rendering of vesicles; numbers correspond to the regions delineated in (A) and (B). The insets depict magnified 3-dimensional surface rendering of the vesicles from region 2 at two different angles, demonstrating the spherical structure of the vesicles (Movie S3). D. 10 nm digital slice from a different 280 nm-thick STEM tomogram of a 7.5-hour PI viral factory, showing membrane structures surrounded by multiple vesicles near viral factories (Movie S4). The inset demonstrates that membrane structures apposing the factories are studded with ribosomes (black arrows). E, F. Two STEM tomogram slices of an 8-hour PI viral factory that are derived from serial sections and are located 480 nm apart. These tomograms reveal that as Mimivirus progeny are assembled, host cisternae are excluded from the membrane assembly zone (Movies S5, S6). Scale bars: 200 nm in A, D; 100 nm in B; 250 nm in E.