This present invention provides C TAB.G5 and C TAB.G5.1 isolated polypeptides comprising the receptor binding domains of C. difficile toxin A and toxin B as set forth in the amino acid sequences of SEQ ID NO: 2 and SEQ ID NO: 4. The C TAB.G5 and C TAB.G5.1 isolated polypeptides may be used to neutralize toxic effects of C. difficile toxin A and/or toxin B.