PMC:7108609 / 11206-12984 JSONTXT

{"target":"https://pubannotation.org/docs/sourcedb/PMC/sourceid/7108609","sourcedb":"PMC","sourceid":"7108609","source_url":"https://www.ncbi.nlm.nih.gov/pmc/7108609","text":"The effect of anti-A antibodies on the S protein/ACE2 interaction was first tested using a monoclonal anti-A. A clear-cut inhibition of the cell adhesion was observed using the monoclonal antibody 3-3A at 2 μg/mL. Specificity of the inhibition was confirmed since a control irrelevant antibody failed to inhibit and the adhesion to Vero cells of S protein-transfected CHO cells lacking the A antigen was not inhibited by the anti-A mAb (Figure 2D). Vero cells do not express the A histo-blood group antigen. Therefore, the inhibition of adhesion mediated by the anti-A mAb can only result from a binding to CHO S protein expressing cells and not to the glycans of ACE2. In order to assay the ability of natural human anti-A to inhibit cell adhesion, plasma samples from two O blood group individuals with high anti-A titers were selected. The samples were first adsorbed on silica beads conjugated to the A type 2 tetrasaccharide in order to specifically remove the anti-A natural plasma antibodies. Efficacy of the adsorption was controlled by ELISA which showed that the reactivity to the A type 2 tetrasaccharide was almost completely abolished following adsorption (Figure 3B). The A type 2 adsorbed and mock adsorbed plasma samples from the two individuals were then added in the cell-based assay. Both mock adsorbed samples, containing the anti-A as shown in Figure 3B, strongly inhibited the adhesion of A antigen-S protein expressing cells to Vero cells. In both cases, this inhibition was almost completely lost after A type 2 adsorption, showing that it was specifically mediated by anti-A plasma antibodies (Figure 3C). Moreover, the inhibition of adhesion by blood group O plasma was dose-dependent and still detected at a plasma dilution as low as 1/32 (Figure 3D).","tracks":[]}