Fig. 4.

Immunogold detection of SARS-CoV-2 nucleocapsid protein in infected cells in the absence or presence of two doses of plitidepsin. Ultrathin sections of cells were incubated with anti-N primary antibody followed by a secondary antibody conjugated with 10 nm colloidal gold particles and visualized by TEM. (A) to (C) Ultrathin sections of cells infected for 48 h with SARS-CoV-2 at an MOI of 0.02. (A) Low magnification image of an infected cell with characteristic DMVs (asterisks) near the nucleus (N). (B) High magnification image of a group of intracellular viruses (arrowheads) inside a vacuole. Viral particles and areas of cytosol are labeled. (C) Labeled extracellular virions (arrows) on the cell surface. (D) to (F) Cells infected 48 h with SARS-CoV-2 at an MOI of 0.02 and treated with 0.05 μM plitidepsin. Low (D) and high (E) and (F) magnification images of cells show no labeling. (G) to (I) Cells infected 48 h with SARS-CoV-2 at an MOI of 0.02 and treated with 0.2 μM plitidepsin. Low (G) and high (H) and (I) magnification images of cells show no labeling. P, plasma membrane. Scale bars, 0.5 μm in A, D and G; 200 nm in B, C, E, F, H and I.