Fig 4. Binding affinity determination of Fab IpaD-318 on yeast cells displaying wild-type IpaD from several Shigella/Salmonella enterica species/serovars.
IpaD or SipD from different species/serovars of Salmonella and Shigella was expressed at the surface of yeast cells. The fluorescence corresponding to Fab IpaD-318 binding was determined by FACS analysis in the presence of increasing concentrations of Fab. Measurements were done in duplicate with independent cultures and inductions. SipD from S. Paratyphi, S. Enteritidis and serovar ST313 all share the same sequence epitope. Apparent KD values and 95% confidence intervals were determined using PRISM software with a one site-specific binding model.