Figure 1.

SARS-2-S and SARS-S Facilitate Entry into a Similar Panel of Mammalian Cell Lines

(A) Schematic illustration of SARS-S including functional domains (RBD, receptor binding domain; RBM, receptor binding motif; TD, transmembrane domain) and proteolytic cleavage sites (S1/S2, S2′). Amino acid sequences around the two protease recognition sites (red) are indicated for SARS-S and SARS-2-S (asterisks indicate conserved residues). Arrow heads indicate the cleavage site.

(B) Analysis of SARS-2-S expression (upper panel) and pseudotype incorporation (lower panel) by western blot using an antibody directed against the C-terminal hemagglutinin (HA) tag added to the viral S proteins analyzed. Shown are representative blots from three experiments. β-Actin (cell lysates) and VSV-M (particles) served as loading controls (M, matrix protein). Black arrow heads indicate bands corresponding to uncleaved S proteins (S0) whereas gray arrow heads indicate bands corresponding to the S2 subunit.

(C) Cell lines of human and animal origin were inoculated with pseudotyped VSV harboring VSV-G, SARS-S, or SARS-2-S. At 16 h postinoculation, pseudotype entry was analyzed by determining luciferase activity in cell lysates. Signals obtained for particles bearing no envelope protein were used for normalization. The average of three independent experiments is shown. Error bars indicate SEM. Unprocessed data from a single experiment are presented in Figure S1.