Table 2

Protection against C. difficile disease in hamsters vaccinated with recombinant TcdA and TcdB fragments with MF59 adjuvanta

Challenge strain and vaccine antigen(s)% Survival (no. of survivors/total no. of animals)Duration of diarrheaAnti-TcdA neutralization titerAnti-TcdB neutralization titer
Strain 630
    TcdA-B1+TcdB-B3100 (6/6)5 h 55 min ± 3 h 25 min4,667 ± 1,764558 ± 121
    TcdA-B1+TcdB-GT100 (6/6)None8,000 ± 0512 ± 0
    Tcd-B1/TcdB-GT chimera60 (3/5)16 h 57 min ± 7 h 39 min1,667 ± 333 (32 ± 0)512 ± 0 (16 ± 0)
    Adjuvant alone0 (0/7)4 h 5 min ± 0 h 44 minc
    Naive animals0 (0/7)3 h 37 min ± 0 h 33 minc
Strain B1
    TcdA-B10 (0/6)NDcNDND
    TcdB-B30 (0/6)NDc0426 ± 85
    TcdA-B1+TcdB-B383 (5/6)24 h 46 min ± 7 h 43 min2,000 ± 0 (32 ± 0)512 ± 0 (16 ± 0)
    TcdA-B1+TcdB-GT100 (6/6)7 h 53 min ± 2 h 34 min1,200 ± 5,060341 ± 85
    TcdA-B2+TcdB-GT100 (6/6)12 h 19 min ± 3 h 4 min8,000 ± 0256 ± 0
    TcdA-B1+TcdB-B3+TcdB-GT83 (5/6)8 h 8 min ± 4 h 59 min1,000 ± 0 (32 ± 0)2,000 ± 0 (32 ± 0)
    TcdA-B2+TcdA-GT+TcdB-B3+TcdB-GT83 (5/6)6 h 1 min ± 1 h 28 min6,667 ± 1,333 (512 ± 0)512 ± 0 (0)
    Adjuvant alone0 (0/10)3 h 2 min ± 0 h 22 minc
    Naive animals0 (0/10)2 h 34 min ± 0 h 17 minc
Strain B1 with reduced antigen dose (20 μg/dose)
    TcdA-B1+TcdB-GT100 (8/8)7 h 25 min ± 2 h 6 min10,000 ± 1,852112 ± 10
    TcdA-B2+TcdB-GT37 (3/8)9 h 39 min ± 4 h 44 min2,133 ± 5,333 (8,000 ± 0)128 ± 0 (0)
    TcdA-B2+TcdA-GT+TcdB-B3+TcdB-GTb86 (6/7)15 h 15 min ± 2 h 3 min8,000 ± 0 (512 ± 0)256 ± 0 (0)
  • a Neutralization titers were determined with pooled sera from protected animals at the experimental endpoint. Values represent geometric means for 3 to 5 independent experiments ± SE. Titers in parentheses refer to single or pooled sera from unprotected animals. ND, not determined.

  • b Sample sera from vaccinated animals were collected before the challenge and showed neutralization titers comparable to those measured at the experimental endpoint (data not shown).

  • c Diarrhea was observed until the body temperature dropped below 35°C.