Figure 2.

In vitro expression of the S1 domain of the spike protein, the nucleocapsid protein, and the receptor-binding domain in HEK293 cells. The recombinant proteins (A) S1, (B) N, and (C) RBD were subjected to SDS-PAGE and Western blot at day 5 and 7 after transfection. Lane 1, molecular weight marker (MW); lane 2, supernatant of cells transfected with parental plasmid (PP); lane 3, supernatant of cells obtained on day 5 after transfection; and lane 4, supernatant of cells obtained on day 7 transfection. The left of each panel shows the Coomassie blue staining, while the right shows the corresponding Western blot detected with anti-His antibodies.