Data and statistical analysis
All statistical tests were performed using GraphPad PRISM 8.0 (GraphPad Software, Inc.). ELISA data in graphs are displayed as enpoint titres measured at a cut off 0.15 OD 450nm. Comparison between RBDWT and mutated RBDs were analyzed by two-ways Anova test for ELISA and paired two-tailed Student‘s t-test for BLI assay. α=0.05 and statistical significance are displayed as p≤0.05 (*), p≤0.01 (**), p≤0.005 (***), p≤0.001 (****).