Binding of an influenza A virus to a neomembrane measured by surface plasmon resonance.

Neomembranes composed of either bovine brain lipid that contains sialoglycolipids or egg yolk lecithin that does not, were formed on an HPA sensor chip and used to study the binding of influenza A virus in real time by surface plasmon resonance. Virus bound only to the bovine brain lipid membrane. This was confirmed by an 84% reduction in virus binding after treatment of the neomembrane with neuraminidase. Binding was temperature dependent, being highest at 30-35 degrees C and lower at 10 degrees C. Surprisingly, the rate of complex formation was enhanced, rather than inhibited, by the presence of 1.34-25.2 x 10(6) molecules of free NANA per virus binding site and the rate of dissociation was lower suggesting that the complex was more stable. The free energy of association to form the transition complex was increased by 3 kJ mol(-1) and there was an almost 10-fold increase in the enthalpy of complex formation in the presence of free NANA. These results show the value of surface plasmon resonance for measuring complex molecular interactions in real time, and provide a model that can be used to study the effectiveness of inhibitors of attachment of influenza virus to its receptor molecules.