Rabbit anti s2 antibody

293T-S cells express the wild-type S glycoprotein from a SARS-CoV-2 Wuhan-Hu-1 strain (Nguyen et al., 2021 ). 293T-S cells were seeded in 6-well plates at a density of 1×106 cells per well on day 0. On day 1, cells were either induced with 1 μg/ml doxycycline or mock treated as a control. Two days after induction, cells were lysed with lysis buffer (1× PBS, 1% NP-40, 1× protease inhibitor cocktail (Roche)). Cell lysates were subjected to Western blotting using the CV3–1 or CV3–25 antibodies; mouse anti-S1 antibody (Sino Biological) and rabbit anti-S2 antibody (Sino Biological) were used as controls. The Western blots were developed with horseradish peroxidase (HRP)-conjugated secondary antibodies (anti-human IgG, anti-mouse IgG or anti-rabbit IgG, correspondingly). To evaluate antibody recognition of S glycoproteins lacking N-linked glycans, 293T-S cells expressing the wild-type SARS-CoV-2 S glycoprotein were lysed with lysis buffer, as described above. Lysates were treated with PNGase F (NEB) following the manufacturer’s instructions or mock treated as a control. The lysates were then Western blotted with the CV3–25 antibody, as described above.