Identification of Clostridium difficile Immunoreactive Spore Proteins of the Epidemic Strain R20291

PurposeClostridium difficile infections are the leading cause of diarrhea associated with the use of antibiotics. During infection, C. difficile initiates a sporulation cycle leading to the persistence of C. difficile spores in the host and disease dissemination. The development of vaccine and passive immunization therapies against C. difficile has focused on toxins A and B. In this study, an immunoproteome-based approach to identify immunogenic proteins located on the outer layers of C. difficile spores as potential candidates for the development of immunotherapy and/or diagnostic methods against this devastating infection is used. Experimental designTo identify potential immunogenic proteins on the surface of C. difficile R20291, spore coat/exosporium extracts are separated by 2D electrophoresis (2-DE) and analyzed for reactivity against C. difficile spore-specific goat sera. Finally, the selected spots are in-gel digested with chymotrypsin, peptides generated are separated by nanoUPLC followed by MS/MS using Quad-TOF-MS, corroborated by Ultimate 3000RS-nano-UHPLC coupled to Q-Exactive-Plus-Orbitrap MS. ResultsThe analysis identify five immunoreactive proteins: spore coat proteins CotE, CotA, and CotCB; exosporium protein CdeC; and a cytosolic methyltransferase. ConclusionThis data provides a list of spore surface protein candidates as antigens for vaccine development against C. difficile infections.