FIG. 6.

Formation of DMVs from ER membranes in vSinEAV(261-1677)His-infected BHK-21 cells. Epon sections (a and b) and cryosections (c and d) of cells fixed at 6 or 9 h p.i. were used. (a) Overview of an infected cell with the square indicating a region which shows abundant DMV formation and closely apposed ER membranes. (b) DMV formation from paired ER membranes. Note the electron-dense neck-like structures (small arrowheads) and the fact that the outer membrane of these DMVs is continuous with the ER membrane, whereas the inner membrane appears to be separated. In both models (see Discussion and Fig. 8), the DMV structure would wrap around a part of the cytoplasm, while the narrow lumen between the two closely apposed DMV membranes would be equivalent to the ER lumen. (c) Cryoimmunolabeling of DMVs using anti-EAV nsp3 serum. (d) Double labeling for EAV nsp3 (large arrowhead, 10-nm gold) and PDI (small arrowheads, 5-nm gold), demonstrating that DMVs and closely apposed ER membranes contain both nsp3 and PDI. PM, plasma membrane; M, mitochondrion. Bars, 200 (a) or 100 (b, c, and d) nm.