RBD mutations protein expression and purification
SARS-CoV-2 RBDwildtype, RBDK417N, RBDE484K, RBDN501Y, RBDK417N/E484K/N501Y, RBDL452R/E484Q were cloned as a synthetic gene into pTWIST-CMV-BetaGlobin-WPRE-Neo vector (Twist Biosciences, CA, USA) and expressed in HEK293F cells through the Expi293 system (ThermoFisher Scientific, MA, USA). Purification was performed by IMAC using a HiTrap TALON crude column (Cytiva, Uppsala, Sweden).