Kinetic analysis of the influenza A virus HA/NA balance reveals contribution of NA to virus-receptor binding and NA-dependent rolling on receptor-containing surfaces
PR8MtSIN and WSNHAMtSIN, both carrying the same HAMtSIN but either NAMtSIN (high NA activity) or NAWSN (low NA activity), respectively, were bound at 30 pM concentration to biotinylated 3’SLN or Fc-tagged 3’N Fetuin loaded to maximum level in the presence (A, D) or absence (B, E) of 10 μM OC. Viruses bound to sensors in presence of OC (A, D) were washed three times in PBS and subsequently examined for NA activity-dependent self-elution in absence of OC (C, F). Virus dissociation in panel C and F is plotted on the positive Y-axis as fraction of virus released relative to the binding level reached in panel A and D respectively. Biotinylated 3’SLN or its fucosylated derivative (SLeX, NeuNAcα2,3Galβ1,4(Fucα1,3)GlcNAc) were loaded to maximum levels on SA sensors and bound with 30 pM PR8MtSIN in the presence (G) or absence (H) of 10 μM OC for 15 minutes. After three washes in PBS the sensors loaded with virus in (G) were incubated in PBS without OC to allow determination of virus self-elution due to NA activity (I).