TABLE 4.

Differences in calculated free energies (ΔΔG) for bezlotoxumab binding to TcdB of different ribotypes and corresponding affinities and neutralization potencies

Ribotype	ΔΔG (kcal/mol)	K′d ratioa	EC50 ratioa
087	0	1	1
027	3.2	26	185
019	3.1	NDb	ND
036	2.3	27	171
078	2.1	15	25
063	2.0	ND	ND
017	−0.6	0.4	0.33

^aFrom values determined by competition ELISA and neutralization studies (Table 1), normalized to values obtained for VPI 10463/ribotype 087.

^bND, not determined.