3.7 | Effect of mAb-EspB-B7 on bacterial-host cell
interaction
To examine the ability of mAb-EspB-B7 to directly interfere with the
bacterial infection of host cells, we examined the translocation
activity of WT EPEC in the presence or absence of mAb-EspB-B7. For that
purpose, we infected HeLa cells with EPEC strains (WT and ΔescN )
and examined the cleavage pattern of JNK, a host protein that is cleaved
by a translocated EPEC effector known as NleD (Figure 7A) (Baruch et
al., 2011). WT EPEC caused extensive degradation of JNK, relative to the
uninfected sample and the samples infected with the ΔescN mutant
strain (Figure 7B). Unfortunately, HeLa cells infected by WT EPEC in the
presence of a high concentration of mAb-EspB-B7 (400 nM) showed
translocation activity similar to that of WT EPEC infection with no
addition of antibody. These results suggest that while mAb-EspB-B7 was
capable of binding EspB with high affinity and specificity, this binding
did not interfere with the protein function and did not inhibit the T3SS
translocation activity in an ex vivo model.