Fig. 1

The expression of the SARS-CoV-2 E protein is restricted to intracellular compartments of the cell. COS-7 cells were transfected with the vector expressing the SARS-CoV-2 E-HA protein. At 24 h, cells were processed for immunostaining. The cells on coverslips were reacted with a mouse monoclonal antibody against HA-tag and with rabbit antibodies against ERGIC53, Golgin-97, or LAMP-1. The cells were washed and reacted with a secondary goat anti-rabbit antibody conjugated to AlexaFluor488 and with a chicken anti-mouse antibody conjugated to AlexaFluor594 for 1 h. Cells on coverslips were counterstained with DAPI and mounted on glass slides with a glycerol-containing mounting medium. To examine the intracellular localization of the E protein with the RER, cis-medial Golgi, or trans Golgi network (TGN), COS-7 cells were co-transfected with the plasmid expressing the E-HA protein, and vectors expressing ERMoxGFP, mNeonGreen-Giantin, or TGN38-GFP. Cells were prepared as above and immunostained with an anti-HA antibody and mounted as above. Coverslips were viewed with a Leica TCS SP8 Confocal Microscope with a 100X objective and a 2X digital zoom using the Leica Application Suite X (LASX) as previously described. A 405 nm filter was used to visualize the DAPI, a 594 nm filter to visualize HA staining, and a 488 nm filter to visualize the cellular markers. A. Cells co-transfected with vectors expressing SARS-CoV-2 E-HA and ERMoxGFP and immunostained with an anti-HA antibody. Scale bar = 20 µm. B. Cells transfected with a vector expressing SARS-CoV-2 E-HA and immunostained with anti-HA and anti-ERGIC53. C. Cells co-transfected with vectors expressing SARS-CoV-2 E-HA and mNeonGreen-Giantin and immunostained with an anti-HA antibody. D. Cells transfected with a vector expressing SARS-CoV-2 E-HA and immunostained with anti-HA and anti-Golgin97. E Cells co-transfected with vectors expressing SARS-CoV-2 E-HA and TGN38-GFP and immunostained with an anti-HA antibody. F Cells transfected with the vector expressing SARS-CoV-2 E-HA and immunostained with an anti-HA and anti-LAMP1