Fig. 2.

ER stress was induced in HEK-293 T cells after overexpressing SARS-CoV-2 orf8. (A and C) HEK-293 T cells were co-transfected with firefly luciferase plasmids harboring the corresponding promoter of GRP78 (A) or GRP94 (C), pRL-null (Renilla plasmid), and either of orf8L, orf8S, orf8b or vector control. The ratio of the reporter (Firefly) to control (Renilla) in relative luminescence units were plotted. (B and D) mRNA levels of GRP78 (B) and GRP94 (D) were examined by qRT-PCR in HEK-293 T cells after treatment with orf8L, orf8S, orf8b and vector control. Orf8L and orf8S referred to SARS-CoV-2, orf8b referred to SARS-CoV * p < 0.05; ** p < 0.01; *** p < 0.001. p values were determined with two-tailed student’s t test. Error bars represent standard deviation S.D.