Clostridium difficile antigens

Abstract

The present application 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 1500-1850 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 . Polyclonal antibodies that bind to a  C. difficile  Toxin B, do not substantially bind to the effector domain and/or to the cysteine protease domain of  C. difficile  Toxin B, and can elicit a  C. difficile  Toxin B-neutralizing immune response,
 wherein said polyclonal antibodies are obtained by immunizing an animal with a fusion protein, comprising a first amino acid sequence and a second amino acid sequence to induce production of polyclonal antibodies specific for  C. difficile  Toxin B, wherein:
 a) the first amino acid comprises an amino acid sequence having at least 90% sequence identity with an amino acid sequence consisting of residues 1444-1851 of a  C. difficile  Toxin B sequence; and 
 b) the second amino acid comprises an amino acid sequence having at least 90% sequence identity with an amino acid sequence consisting of a long repeat unit located within amino acid residues 1852-2366 of a  C. difficile  Toxin B sequence; 
   with the proviso that the fusion protein is not a polypeptide comprising amino acid residues 543-2366 of the  C. difficile  Toxin B; 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 polyclonal antibodies according to  claim 1 , wherein the fusion protein comprises an amino acid sequence having at least 90% sequence identity with:
 a) amino acid residues 767-2366 of said  C. difficile  Toxin B sequence; or   b) amino acid residues 1145-2366 of said  C. difficile  Toxin B sequence.   
     
     
         3 . The polyclonal antibodies according to  claim 1 , wherein the animal is horse, sheep, goat, or human. 
     
     
         4 . The polyclonal antibodies according to  claim 1 , wherein the polyclonal antibodies are isolated. 
     
     
         5 . The polyclonal antibodies according to  claim 4 , wherein the polyclonal antibodies are isolated by affinity purification. 
     
     
         6 . A method for preventing, treating or suppressing  C. difficile  infection in a human, said method comprising administering to said human a therapeutically effective amount of polyclonal antibodies according to  claim 1 . 
     
     
         7 . The method according to  claim 6 , wherein said polyclonal antibodies are administered in combination with one or more additional antibodies, wherein the one or more additional antibody is an antibody that binds to a  C. difficile  non-Toxin antigen, and/or is an antibody that binds to a whole cell  C. difficile  bacterium. 
     
     
         8 . The method according to  claim 7 , wherein the one or more antibody is selected from:
 a) an antibody that binds to antigen from a bacterium that causes nosocomial infection, and/or   b) an antibody that binds to a whole cell bacterium that causes nosocomial infection.   
     
     
         9 . The method according to  claim 6 , wherein the polyclonal antibody is combined with one or more antibiotic. 
     
     
         10 . The method according to  claim 9 , wherein the antibiotic is an antibiotic effective against a bacterium that causes a nosocomial infection. 
     
     
         11 . The method according to  claim 7 , wherein the one or more antibody is combined with one or more antibiotic. 
     
     
         12 . The method according to  claim 11 , wherein the antibiotic is an antibiotic effective against a bacterium that causes nosocomial infection. 
     
     
         13 . A method for treating a  C. difficile  infection in a patient comprising:
 using an in vitro immunoassay method to confirm the presence or absence of a  C. difficile  infection in a patient sample, wherein said immunoassay comprises the steps of:
 combining the patient sample with the polyclonal antibodies according to  claim 1  for a time sufficient for antibody binding with  C. difficile  Toxin B present in the patient sample; 
 detecting the presence of antibody binding with  C. difficile  Toxin B in the patient sample; 
   wherein the presence of a  C. difficile  infection is confirmed by detecting the binding of said polyclonal antibodies to a  C. difficile  Toxin B present in said patient sample,   wherein failure to detect the binding of said polyclonal antibodies to a  C. difficile  Toxin B present in said patient sample confirms the absence of a  C. difficile  infection, and   wherein the said patient confirmed as having  C. difficile  in said patient sample is administered a therapeutically effective amount of the polyclonal antibodies of  claim 1 .