Characterization of the wild-type C. difficile 630Δerm strain, fliC and fliD ClosTron interruption mutants, and their respective complemented strains. (A and C) Swim agar assays revealing the motility phenotypes of the wild-type 630Δerm, Cdi-fliC-260a, p84151 fliC/Cdi-fliC-260a, Cdi-fliD-322a, and p84151 fliD/Cdi-fliD-322a C. difficile strains. (B and D) Western immunoblot analyses of the wild-type 630Δerm (lanes 1 and 4), Cdi-fliC-260a (lane 2), p84151 fliC/Cdi-fliC-260a (lane 3), Cdi-fliD-322a (lane 5), and p84151 fliD/Cdi-fliD-322a (lane 6) strains probed with FliC- and FliD-specific IgY.