The present invention relates to recombinant C. difficile toxin A (TcdA) and toxin B (TcdB) and binary toxin A (CDTa) proteins comprising specifically defined mutations relative to the native toxin sequence that substantially reduce or eliminate toxicity. The invention also relates to vaccines and immunogenic compositions comprising these recombinant toxins, as well as combinations of these toxins with binary toxin B (CDTb), which are capable of providing protection against C. difficile infection and/or the effects thereof. The invention also relates to methods of inducing an immune response to C. difficile comprising administering the vaccines and immunogenic compositions described herein to a patient. The invention also encompasses methods of expressing recombinant C. difficile toxin A and toxin B and CDTa mutants and CDTb in recombinant expression systems. In exemplary embodiments, TcdA, TcdB, and CDTa mutant toxins comprising sufficient mutations to substantially reduce or eliminate toxicity are expressed in the baculovirus/insect cell expression system.本發明係關於重組難養芽胞梭菌(C.difficile)毒素A(TcdA)及毒素B(TcdB)及二元毒素A(CDTa)蛋白質，其包含實質上比天然毒素序列降低或消除毒性之明確限定之突變。本發明亦係關於包含此等重組毒素及此等毒素與二元毒素B(CDTb)之組合之疫苗及免疫原性組合物，其可防止難養芽胞梭菌感染及/或其影響。本發明亦係關於誘導針對難養芽胞梭菌之免疫反應之方法，其包括將本文所述之疫苗及免疫原性組合物投與患者。本發明亦涵蓋在重組表現系統中表現重組體難養芽胞梭菌毒素A及毒素B及CDTa突變體及CDTb之方法。在示例性實施例中，包含足以實質上降低或消除毒性之突變之TcdA、TcdB及CDTa突變毒素係在桿狀病毒/昆蟲細胞表現系統中表現。
