Table 1

Mice immunized with various amount of rRBD (µg)		Anti-rRBDIgGtitersa	Neutralization Titerb
Mice immunized with various amount of rRBD (µg)		Anti-rRBDIgGtitersa	TcdB	TcdA
0	Pre-immune	<100	<4	<4
	2 doses	<100	NP	NP
	3 doses	<100	<4	NP
3	Pre-immune	<100	<4	<4
	2 doses	400	NP	NP
	3 doses	800	16	16
10	Pre-immune	<100	<4	<4
	2 doses	400	NP	NP
	3 doses	3200	64	16
TcdARBDc	3 × 10 µg	800	<4	256
aThe titers were obtained with sera pooled from 6 mice bThe neutralization titer against toxins was defined as the highest sample dilution which could prevent 50% cell rounding induced by toxins cThe immunogenicity studies of TcdA RBD will be published elsewhere *NP means not performed

Table 1: C. difficile toxin B neutralization titers of antisera from groups of 6 mice immunized 3 times with varying amounts of rRBD.