REAGENT or RESOURCE	SOURCE	IDENTIFIER
ExpiCHO Expression System Kit	Thermo Fisher Scientific	Cat# A29133
Expi293 Expression System Kit	Thermo Fisher Scientific	Cat# A14635
Insect-XPRESS protein-free insect cell medium	Lonza Bioscience	Cat# 12-730Q
FreeStyle 293 expression medium	GIBCO	Cat# 12338002
Opti-MEM I reduced serum media	GIBCO	Cat# 51985091
Phosphate-buffered saline (PBS)	Thermo Fisher Scientific	Cat# 14040133
Ni-NTA Superflow	QIAGEN	Cat# 30450
Ni Sepharose excel	Cytiva	Cat# 17371202
DH10Bac competent cells	Thermo Fisher Scientific	Cat# 10361012
CaptureSelect CH1-XL Affinity Matrix	Thermo Fisher Scientific	Cat# 2943452010
Protein A column	Thermo Fisher Scientific	Cat# 17040301
Fetal Bovine Serum	Omega Scientific	Cat# FB-02
Antibodies
Donkey anti-human IgG-HRPO	Dianova	Cat# 709-035-149, RRID: AB_2340495
Donkey F(ab’)2 anti-rabbit IgG-HRPO	Dianova	Cat# 711-036-152; RRID: AB_2340590
Chemicals and Recombinant Proteins
DpnI	New England Biolabs	Cat# R0176L
Trypsin	New England Biolabs	Cat# P8101S
Fugene 6 Transfection Regent	Promega	Cat# E2691
Sodium chloride (NaCl)	Sigma-Aldrich	Cat# S9888
Tris Base	Sigma-Aldrich	Cat# 11814273001
Concentrated hydrochloric acid (HCl)	Sigma-Aldrich	Cat# H1758
Sodium azide (NaN3)	Sigma-Aldrich	Cat# S2002
Bovine Serum Albumin (BSA)	Sigma-Aldrich	Cat# A9418
Tween 20	Fisher Scientific	Cat# BP337-500
PEImax	Polysciences	Cat# 24765-1
Chemicals for protein crystallization	Hampton Research	N/A
1-step Ultra TMB-ELISA	Thermo Fisher Scientific	Cat# 34028
Critical Commercial Assays
In-Fusion HD Cloning Kit	Takara	Cat# 639647
KOD Hot Start DNA Polymerase	EMD Millipore	Cat# 71086-3
PCR Clean-Up and Gel Extraction Kit	Clontech Laboratories	Cat# 740609.250
QIAprep Spin Miniprep Kit	QIAGEN	Cat# 27106
NucleoBond Xtra Maxi	Clontech Laboratories	Cat# 740414.100
Deposited Data
X-ray coordinates and structure factors of CV38-142 Fab in complex with SARS-CoV-2 RBD and COVA1-16 Fab	This study	PDB: 7LM8
X-ray coordinates and structure factors of CV38-142 Fab in complex with SARS-CoV RBD	This study	PDB: 7LM9
Electron microscopy map of SARS-CoV spike in complex with Fab CV38-142 (three Fabs bound)	This study	EMDB: EMD-23469
Electron microscopy map of SARS-CoV spike in complex with Fab CV38-142 (two Fabs bound)	This study	EMDB: EMD-23470
Electron microscopy map of SARS-CoV-2 spike in complex with Fab CV38-142 (three Fabs bound)	This study	EMDB: EMD-23471
Electron microscopy map of SARS-CoV-2 spike in complex with Fab CV38-142 (two Fabs bound)	This study	EMDB: EMD-23472
Cell Lines
ExpiCHO cells	Thermo Fisher Scientific	Cat# A29127; RRID: CVCL_5J31
Expi293F cells	Thermo Fisher Scientific	Cat# A14527; RRID: CVCL_D615
FreeStyle 293-F cells	Thermo Fisher Scientific	Cat# R79007; RRID: CVCL_D603
Expi293S cells	Thermo Fisher Scientific	Cat# A39240
HEK293T cells	ATCC	Cat# CRL-3216; RRID: CVCL_0063
Sf9 cells	ATCC	Cat# CRL-1711; RRID: CVCL_0549
High Five cells	Thermo Fisher Scientific	Cat# B85502; RRID: CVCL_C190
DH10Bac competent cells	Thermo Fisher Scientific	Cat# 10361012
Recombinant DNA
phCMV3-COVA1-16 IgG heavy chain	(Brouwer et al., 2020)	N/A
phCMV3-COVA1-16 Fab heavy chain	(Brouwer et al., 2020)	N/A
phCMV3-COVA1-16 light chain	(Brouwer et al., 2020)	N/A
phCMV3-CV38-142 IgG heavy chain	This study	N/A
phCMV3-CV38-142 Fab heavy chain	This study	N/A
phCMV3-CV38-142 light chain	This study	N/A
pFastBac-SARS-CoV-RBD	(Yuan et al., 2020a)	N/A
pFastBac-SARS-CoV-2-RBD	(Yuan et al., 2020a)	N/A
phCMV3-ACE2	This study	N/A
Software and Algorithms
HKL2000	(Otwinowski and Minor, 1997)	N/A
Phaser	(McCoy et al., 2007)	N/A
Coot	(Emsley et al., 2010)	N/A
Phenix	(Adams et al., 2010)	N/A
MolProbity	(Chen et al., 2010)	N/A
Sc	(Lawrence and Colman, 1993)	N/A
PyMOL	Schrödinger, LLC	RRID: SCR_000305
Appion	(Lander et al., 2009)	N/A
DoG Picker	(Voss et al., 2009)	N/A
Relion	(Scheres, 2012)	N/A
UCSF Chimera	(Pettersen et al., 2004)	N/A
Octet Analysis Software 12.0	Sartorius	https://www.moleculardevices.com
Other
Fab-CH1 2nd generation (FAB2G) biosensors	Sartorius	Cat# 18-5125
Anti-Human Fc Capture (AHC) Biosensors	Sartorius	Cat# 18-5060
Ni-NTA biosensors	Sartorius	Cat# 18-5101
Streptavidin (SA) biosensors	Sartorius	Cat# 18-5057
Biotin CAPture Kit, Series S	Cytiva	Cat# 28920234
HiLoad 16/600 Superdex 200 pg	Cytiva	Cat# 28989335
HiLoad 16/600 Superose 6 pg	Cytiva	Cat# 29323952
Negative stain EM grids, 400 mesh	Electron Microscopy Sciences	Cat# EMS400-CU