Skip to main content
. 2023 Jan 23;19(1):e1011128. doi: 10.1371/journal.ppat.1011128

Fig 2. SARS-CoV-2 ORF8, rather than SARS-CoV ORF8, has an unconventional secretion pattern.

Fig 2

(A) Structures of SARS-CoV-2 ORF8 and its signal peptide-deleted mutant. (B, C) Full-length SARS-CoV-2 ORF8 or its signal peptide-deleted mutant was transfected into Calu-3 cells or HEK-293FT cells. The secretion of ORF8 was detected by western blotting (B) and ELISA (C). (D, E) Brefeldin A (3 μg/mL) or Monensin (2 μM) was used to pretreat Calu-3 cells (D) or HEK-293FT cells (E) for 2 hours. Full-length SARS-CoV-2 ORF8 was transfected into pretreated cells. After 12 hours, the secretion of ORF8 was detected by western blotting. (F) Structures of SARS-CoV ORF8a and its signal peptide-deleted mutant. (G) Full-length SARS-CoV ORF8a or its signal peptide-deleted mutant were transfected into Calu-3 cells or HEK-293FT cells. The secretion of ORF8a was detected by western blotting. (H, I) Brefeldin A or Monensin was used to pretreat Calu-3 cells (H) or HEK-293FT cells (I) for 2 hours. Full-length SARS-CoV ORF8a was transfected into pretreated cells. After 12 hours, the secretion of ORF8a was detected by western blotting. (J) Structures of SARS-CoV-2 ORF8 mutant with signal peptide from SARS-CoV ORF8a (with SARS-Signal), and SARS-CoV ORF8a mutant with signal peptide from SARS-CoV-2 ORF8 (with SARS-CoV-2-Signal). (K) Brefeldin A or Monensin was used to pretreat Calu-3 cells for 2 hours. SARS-CoV-2 ORF8 with SARS-CoV-Signal and SARS-CoV ORF8a with SARS-CoV-2-Signal were transfected into pretreated Calu-3 cells. After 12 hours, the secretion of ORF8 was detected by western blotting. Representative images from n = 3 biological replicates are shown (B, D, E, G-I, K). Data are shown as the mean ± s.e.m. of n = 6 biological replicates (C). Unpaired two-tailed Student t test (C) was used for data analysis. **, p < 0.01.