Immunogenic composition comprising elements of c. difficile cdtb and/or cdta proteins

Abstract

The present invention relates to immunogenic compositions comprising isolated Clostridium difficile CDTb and/or CDTa protein. In particular the isolated Clostridium difficile CDTb protein is suitably a truncated CDTb protein comprising the receptor binding domain or a mutated CDTb protein incapable of binding to CDTa, and the isolated Clostridium difficile CDTa protein is suitably a truncated CDTa protein which does not comprise the C-terminal domain. In particular the invention also relates to fusion proteins comprising a CDTa protein and a CDTb protein and also fusion proteins between an isolated Clostridium difficile toxin A protein and/or an isolated Clostridium difficile toxin B protein fused to a CDTb protein.

1 . An immunogenic composition comprising a fusion protein, said fusion protein comprising a  Clostridium difficile  binary toxin a (CDTa) protein sequence covalently linked to a  Clostridium difficile  binary toxin b (CDTb) protein sequence, wherein:
 (a) the CDTa protein sequence comprises the CDTa C-terminal domain, and   (b) the CDTb protein sequence lacks the CDTb prodomain sequence and is selected from a sequence comprising amino acids 212-876 of SEQ ID NO: 3, SEQ ID NO:9, and a sequence having at least 95% sequence identity to SEQ ID NO:9.   
     
     
         2 . A vaccine comprising the immunogenic composition of  claim 1  and a pharmaceutically acceptable excipient. 
     
     
         3 . A method of preventing or treating  C. difficile  disease comprising administering the vaccine of  claim 2  to a human subject. 
     
     
         4 . The immunogenic composition of  claim 1 , wherein said CDTa protein includes an amino acid substitution selected from R345K, Q350A, N385A, R402A, S388F, E428Q, and E430Q, where the amino acid numbering corresponds to that of SEQ ID NO: 1. 
     
     
         5 . The immunogenic composition of  claim 1 , wherein in said fusion protein, the CDTa protein sequence and CDTb protein sequence are covalently linked via a peptide linker. 
     
     
         6 . The immunogenic composition of  claim 1 , wherein the immunogenic composition further comprises an isolated  Clostridium difficile  toxin A protein and/or an isolated  C. difficile  toxin B protein. 
     
     
         7 . The immunogenic composition of  claim 1 , wherein the immunogenic composition further comprises a fusion protein of  Clostridium difficile  toxin A protein and  C. difficile  toxin B protein. 
     
     
         8 . The immunogenic composition of  claim 7 , wherein the fusion protein is
 (i) SEQ ID NO: 18, 19, 20, 21, 22, 24, 26, 28, or 30; or   (ii) a variant having at least 95% sequence identity to SEQ ID NO: 18, 19, 20, 21, 22, 24, 26, 28, or 30; or   (iii) a fragment of at least 900 continuous amino acids of a sequence selected from the group consisting of SEQ ID NO: 18, 19, 20, 21, 22, 24, 26, 28, and 30.