Table 1

Neutralization titers of sera from mice immunized with toxin A and B fragmentsa

Antigen(s)Anti-TcdA neutralization titerAnti-TcdB neutralization titer
Al(OH)3MF59Al(OH)3MF59
TcdA-B12,102 ± 5552,667 ± 66616 ± 016 ± 0
TcdA-B211,200 ± 1,9606,400 ± 97900
TcdA-B34,400 ± 9762,800 ± 48900
TcdA-B40ND0ND
TcdA-CP0000
TcdA-GT1,333 ± 333208 ± 4800
TcdB-B10000
TcdB-B20000
TcdB-B300320 ± 64213 ± 42
TcdB-CP0000
TcdB-GT00298 ± 112224 ± 32
TcdA-B1+TcdB-B38,000 ± 05,500 ± 1,500256 ± 0298 ± 112
TcdA-B1+TcdB-GT7,000 ± 1,0004,667 ± 1,764160 ± 32171 ± 43
TcdA-B2+TcdB-B34,000 ± 1,0954,667 ± 1,764256 ± 0256 ± 0
TcdA-B2+TcdB-GT7,333 ± 1,9098,000 ± 2,828170 ± 43256 ± 0
TcdA-B3+TcdB-B34,667 ± 1,7644,667 ± 1,764170 ± 42128 ± 0
TcdA-B3+TcdB-GT5,333 ± 1,3332,000 ± 1,000149 ± 56170 ± 43
TcdA-B1/TcdB-GT chimerab3,500 ± 5004,000 ± 000
  • a The titer was defined as the reciprocal of the highest dilution able to inhibit 100% rounding in IMR-90 human fibroblasts treated with 1 CTU100 of toxin A or B. Values represent the geometric means for 3 to 5 independent experiments ± standard errors (SE). Combinations selected for testing in the hamster animal model are indicated in bold. ND, not determined.

  • b TcdA-B1 and TcdB-GT were also combined in a single chimeric polypeptide (TcdA-B1/TcdB-GT).