T3SS
To examine whether mAb-EspB-B7 can bind to the native protein in the
assembled T3SS, we used flow cytometry. For this purpose, the bacterial
strains grown under T3SS-inducing conditions were incubated first with
mAb-EspB-B7 and then with a secondary antibody conjugated to a
fluorophore. As expected, mAb-EspB-B7 binding was detected in WT EPEC
and in the ΔespB strain overexpressing EspB, whereas no or
minimal binding was detected in the ΔescN and ΔespB mutant
strains (Figure 2B).