Table 1.

Receptor-binding domain (RBD) constructs used in this work. Listed are the construct names/reference numbers, the amino acid region of SARS-CoV-2 spike utilized in the construct, the signal peptide (S = SARS-CoV-2 spike, TPA = human tissue plasminogen activator), the C-terminal tag attached to the RBD region (His6/His8 = polyhistidine tags, 3C = HRV3C protease cleavage site, SBP = streptavidin-binding peptide), the promoter used to drive transcription of the gene of interest (CAG = chicken beta-actin promoter with human CMV enhancer, HTLV = HTLV1 5’ UTR, CMV51 = enhanced cytomegalovirus immediate early promoter/enhancer), and the backbone vector utilized.

0BConstruct	1BSpike region	2BSig peptide	3BC-tag	4BPromoter	5BVector
6BX22 (Sinai)	319–541	S (1–14)	His6	CAG	pCAGGS
7BM67 (FNL-S)	319–541	S (1–14)	His6	CMV51	pDest-303
8BX24 (Ragon)	319–529	9BTPA (1–22)	10B3C-His8-SBP	11BCMV-HTLV	12BpVRC
13BM68 (FNL-R)	319–529	14BTPA (1–22)	15B3C-His8-SBP	16BCMV51	17BpDest-303
18BM69 (FNL-R)	319–529	19BTPA (1–22)	20B3C-His8	21BCMV51	22BpDest-303