FIG 1.

(A) Size exclusion chromatograms postpurification of FL-NP, FL-S, CR3022, RBD, and ACE2. All proteins were run individually with chromatograms overlaid. Asterisks indicate the fractions run on SDS-PAGE. (B) Nonreducing (NR) and reducing (R) Coomassie blue-stained SDS-PAGE protein gels of 1 μg of protein from the asterisk-indicated fractions. (C) Freeze-thaw stability of FL-S and RBD. Reducing and nonreducing SDS-PAGE protein gel of 1 μg FL-S (red outline) and RBD (orange outline) after 1, 2, and 3 freeze-thaw cycles. Below each gel a dot blot is shown, using the CR3022 human MAb on 1 μg FL-S and RBD after 1, 2, and 3 freeze-thaw cycles.