Table 1 Prefusion-stabilized spike trimer variants and characteristics

S-2P

K986P, V987P, furin^a

Proline

0.5 mg/L

FreeStyle 293-F

Wrapp et al.¹⁹

HexaPro

K986P, V987P, F817P, A892P, A899P, A942P, furin^a

Proline

10.5 mg/L (FreeStyle 293-F)

32.5 mg/L (ExpiCHO)

FreeStyle 293-F

ExpiCHO

Hsieh et al.³⁶

rS2d

K986P, V987P, S383C, D985C, furin^a

Disulfide

Not reported

FreeStyle 293-F

Henderson et al.²¹

u1S2q

A570L T572I F855Y N856I (u1S2q)

K986P, V987P, A570L, T572I, F855Y, N856I, furin^a

Cavity filling

Not reported

FreeStyle 293-F

Henderson et al. ²¹

S-R/PP/x1

K986P, V987P, S383C, D985C, furin ^b

Disulfide

~0.4 mg/L

Expi293F

Xiong et al.⁵⁷

S-R/x2

K986P, G413C, V987C, furin^b

Disulfide

~0.4 mg/L

Expi293F

Xiong et al.⁵⁷

S-closed +Fd

K986P, V987P, D614N, A892P, A942P, V987P, furin^a

Cavity filling/proline

Sixfold increased relative to S-2P

Expi293F

Juraszek et al.⁵³

2P DS S

K986P, V987P, S383C/D985C, furin^c

Disulfide

Tenfold reduced relative to S-2P

FreeStyle 293-F

McCallum et al.⁵⁶

N234A

K986P, V987P, N234A

Glycan deletion

2.0 mg/L

FreeStyle 293-F

Henderson et al.⁵⁸

VFLIP

F817P, A892P, A899P, A942P, K986P, Y707C, T883C, K986, furin^d

Proline, disulfide, linker

7.1 mg/L (HEK293F)

157 mg/L (ExpiCHO)

HEK293F

ExpiCHO

Olmedillas et al.⁷³