Figure 2

SARS-CoV-2 N protein, but not S protein, induced IL-6 production. The levels of IL-6 were measured by ELISA 2 days after treatment (A, C, and F). (A) K-ML2 cells were stimulated with the lysate of 293 T cells transfected with plasmids encoding each of the SARS-CoV-2 proteins. (B) The expression of each viral protein confirmed by western blot using the anti-Strep tag. The images from three membranes were combined. The original images with different exposure time are shown in Fig. S3. (C) K-ML2 cells were stimulated with serially diluted S or N protein produced using a baculovirus expression system. The mean and standard deviation of triplicate samples are shown. (D) A schematic diagram of full-length and truncated N proteins. (E) Anti-NTD (N2) antibody and anti-CTD (C2) antibody were used to visualize the full-length and truncated N proteins by western blot. The images from two membranes transferred from a single gel were combined. A blue vertical dividing line of two membranes is shown. The original images with different exposure time are shown in Fig. S3. (F) K-ML2 cells were stimulated with the cell lysates of 293 T cells expressing the full-length or truncated N proteins. Data are expressed as the mean and standard deviation of triplicate samples. The representative results of three independent experiments are shown.