Viruses are rolling over the receptor surface before NA activity-driven dissociation takes place.

(A-D) Virus dissociation of the indicated viruses in the absence of OC is plotted on the positive Y-axis as fraction of virus released relative to the binding level reached in the presence of OC (indicated in nm and shown in S9 Fig). (E) PR8_MtSIN was bound in duplicate at four virus concentrations to eight SA sensors containing biotinylated 3’N+O fetuin bt in presence of 10 μM OC. (F) Viruses bound to the sensors in (E) were allowed to dissociate at each concentration in absence or presence of OC for 15 minutes. (G) Virus dissociation in panel F is plotted on the positive Y-axis as fraction of virus released relative to the binding level reached in panel E. (H) After the dissociation step (F), sensors were regenerated at pH2, thereby removing all bound viruses but leaving the 3’N+O fetuin bt bound to the sensor. All regenerated sensors were subsequently allowed to re-bind PR8_MtSIN at a concentration of 100 pM to determine the degree of de-sialylation that occurred in (F).