Figure 1.

Impact of C33–C102 noncanonical disulfide bond on VHH R303 affinity and inhibitory activity. (a) Solid phase binding assay of VHH R303 and R303^C33A/C102A toward immobilized inlb₂₄₉. (b) Fluorescent microscopy invasion assay measuring VHH mediated inhibition of Listeria invasion.22 HeLa cells were infected with biotinylated L. monocytogenes expressing GFP in the presence of PBS buffer control, InlB_{2 49} (positive control to inhibit Listeria invasion), VHH negative control,25 and R303, and R303^C33A/C102A Only extracellular bacteria are stained red, indicating that both R303, and R303^C33A/C102A inhibit Listeria invasion