Fig. 3

Transmission EM of a thin section through the sediment of swab sample 7 (Epon embedding). A Overview of ciliated cell which shows several cilia (ci) in this profile and which is surrounded by vesicular material and gold colloid (*). Membrane-bound inclusions (arrows) with virus particles and double-membrane vesicles (DMVs; rectangle) are visible in the cytoplasm. The inset shows a magnified view of the cytoplasmic region marked with the rectangle which contain a group of DMVs (See also Additional file 7: Fig S4B). B-E Another ciliated cell than in A which shows virus particles at the surface (C) and in membrane-bound compartments (D, E). Note that the overall spike visibility in this sample is sufficient. Scale bar in A = 2 µm, inset and B = 0.5 µm, C-E = 100 nm