(A) Representative FACS traces for three ELISA+ α-LptD mAbs, 27C2 (purple), 3D10 (blue), and 27C8 (red), with E. coli ΔwaaD (top) and E. coli K-12 (bottom) cells. A non-binding isotype control mAb is shown in grey. 10,000 events were counted for each antibody and counts at each fluorescent intensity were plotted. (B) FACS analysis of a representative E. coli K-12 FACS+ α-LptD mAb (27C8) for binding to E. coli ΔwaaD strains expressing wild-type LptD and the 12 viable loop deletion strains. Loop 10 could not be assessed (see text). The mean fluorescent intensities (MFIs) are plotted. The red dashed line represents a descriptive MFI level that is 10% that of the WT control.