The present invention relates to recombinant Clostridium difficile antigens based on a polypeptide, consisting of or comprising an amino acid sequence having at least 80% sequence identity with an amino acid sequence consisting of residues 1500-700 of a C. difficile Toxin A sequence or a C. difficile Toxin B sequence; though with the proviso that the polypeptide does not include one or more Repeat Unit (RU) located between amino acid residues 1851-2710 of C. difficile Toxin A and/or residues 1853-2366 of a C. difficile Toxin B protein that consists of or comprises a first amino acid sequence and a second amino acid. 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 polypeptide, comprising an amino acid sequence having at least 80% sequence identity with an amino acid sequence consisting of residues 1400-1800 of a Clostridium difficile ( C. difficile ) Toxin B sequence corresponding to SEQ ID NO:2 or SEQ ID NO:4;
with the proviso that the polypeptide does not include one or more of the Repeat Units (RU) located between amino acid residues 1853-2366 of said C. difficile Toxin B sequence.
2. The polypeptide according to claim 1 , wherein said polypeptide does not include the amino acid sequence provided by amino acid residues 1853-2366 of said C. difficile Toxin B sequence.
3. The polypeptide according to claim 1 , wherein the polypeptide comprises an amino acid sequence having at least 80% sequence identity with an amino acid sequence consisting of residues 1145-1852, residues 767-1852, or residues 543-1852 of said C. difficile Toxin B sequence.
4. The polypeptide according to claim 1 , wherein said polypeptide further comprises a second amino acid sequence; wherein said second amino acid sequence is the amino acid sequence of one or more of a bacterial surface layer protein, NusA, thioredoxin, maltose-binding protein, or an ubiquitin-like peptide, or a fragment of any of said second amino acid sequences.
5. The polypeptide according to claim 4 , wherein the second amino acid sequence comprises the amino acid sequence of a C. difficile surface layer protein.
6. The polypeptide according to claim 5 , wherein the amino acid sequence of the C. difficile surface layer protein comprises an amino acid sequence that has at least 80% sequence identity with amino acid residues 27-401 of the CD2767 peptide of SEQ ID NO:16.
7. A method of inducing an immune response in a subject, said method comprising administering an effective amount of a polypeptide according to claim 1 .
8. A method of inducing an immune response in a subject, said method comprising administering an effective amount of a polypeptide according to claim 2 .
9. A method of inducing an immune response in a subject, said method comprising administering an effective amount of a polypeptide according to claim 3 .
10. A method of inducing an immune response in a subject, said method comprising administering an effective amount of a polypeptide according to claim 4 .
11. A method of inducing an immune response in a subject, said method comprising administering an effective amount of a polypeptide according to claim 5 .
12. A method of inducing an immune response in a subject, said method comprising administering an effective amount of a polypeptide according to claim 6 .