The present invention relates to recombinant Clostridium difficile antigens based on a fusion protein that consists of or comprises a first amino acid sequence and a second amino acid sequence, wherein: a) the first amino acid sequence is provided by an amino acid sequence that has at least 80% sequence identity with an amino acid sequence consisting of residues 500-1850 of a C. difficile Toxin A sequence or residues 1500-1851 of a C. difficile Toxin B sequence; and b) the second amino acid sequence is provided by an amino acid sequence that has at least 80% sequence identity with an amino acid sequence consisting of a long repeat unit located within amino acid residues 1851-2710 of a C. difficile Toxin A sequence or within amino acid residues 1852-2366 of a C. difficile Toxin B sequence; though with the proviso that the fusion protein is not a polypeptide comprising amino acid residues 543-2710 of a C. difficile Toxin A and with the proviso that the fusion protein is not a polypeptide comprising amino acid residues 543-2366 of a C. difficile Toxin B. Also provided is the use of said antigens for the prevention/treatment/suppression of Clostridium difficile infection (CDI), together with methods for generating said antigens, methods for generating antibodies that bind to said antigens, and the use of said antibodies for the prevention/treatment/suppression of CDI.
1. A protein, comprising
a) an amino acid sequence that comprises amino acid residues 767-2366 of a C. difficile Toxin B sequence; or
b) an amino acid sequence that comprises amino acid residues 1145-2366 of a C. difficile Toxin B sequence;
with the proviso that the protein is not a polypeptide comprising amino acid residues 543-2366 of the C. difficile Toxin B;
wherein the protein can elicit a toxin-neutralizing immune response; and
wherein said C. difficile Toxin B sequences are the C. difficile Toxin B amino acid residue sequence 767-2366 or 1145-2366 of SEQ ID NO:2 or the C. difficile Toxin B amino acid residue sequence 767-2366 or 1145-2366 of SEQ ID NO:4.
2. The protein according to claim 1 , wherein other than the above-defined Toxin B amino acid sequences, said protein does not include any additional Toxin B amino acid sequence.
3. A method of generating an antibody that binds to a C. difficile Toxin B, the method comprising:
immunizing an animal with the protein according to claim 1 to induce production of an antibody specific for C. difficile Toxin B.
4. The method according to claim 3 , further comprising the step of isolating the antibody specific for C. difficile Toxin B from the immunized animal.
5. The method according to claim 4 , wherein the antibody is isolated by affinity purification.
6. The method according to claim 3 , wherein the animal is horse, sheep, goat, or human.
7. A protein, consisting of:
a) amino acid residues 767-2366 of a C. difficile Toxin B sequence; or
b) amino acid residues 1145-2366 of a C. difficile Toxin B sequence;
wherein the protein can elicit a toxin-neutralizing immune response; and
wherein said C. difficile Toxin B sequences are the C. difficile Toxin B amino acid residue sequence 767-2366 or 1145-2366 of SEQ ID NO:2 or the C. difficile Toxin B amino acid residue sequence 767-2366 or 1145-2366 of SEQ ID NO:4.