Western blot analysis, using antibodies against TcdC, confirmed that the isogenic tcdC mutant no longer expressed TcdC ( Figure 1D ). A control blot using antibodies against F 0 F 1 ATPase indicated that the lack of signal in the TcdC Western blot was not a result of lower amounts of proteins loaded in the lanes of PCR ribotype 035 (a PaLoc negative strain) and the tcdC mutant.