Gene construction

The recombinant protein COVID-19 virus RBD was constructed into two vectors. Residues 331-532 (accession number EPI_ISL_402119) were cloned into pET21a for isolating MAbs as a bait. The coding sequences of COVID-19 RBD (residues 331-532), SARS-CoV RBD (residues 306-527, accession number NC_004718), and hACE2 (residues 19-615, accession number BAJ21180) were used in assays of SPR, BLI and crystal screening were constructed into pFastBac1 plasmid with an N-terminal gp67 signal peptide and a C-terminal six histidine tag. The pEGFP-N1-hACE2 plasmid was constructed by cloning the coding region into pEGFP-N1 vector using restriction enzymes XhoI and SmaI.