DETERMINATION OF THE AFFINITY AND KINETIC CONSTANTS FOR THE INTERACTION BETWEEN THE HUMAN VIRUS ECHOVIRUS-11 AND ITS CELLULAR RECEPTOR, CD55

The biochemical properties of the molecular interactions mediating vir al-cell recognition are poorly characterized. In this study, we use su rface plasmon resonance to study the affinity and kinetics of the inte raction of echovirus 11 with its cellular receptor decay-accelerating factor (CD55). As reported for interactions between cell-cell recognit ion molecules, the interaction has a low affinity (K-D similar to 3.0 mu m) as a result of a very fast dissociation rate constant (k(on) sim ilar to 10(5) m(-1). s(-1), k(off) -0.3 s(-1)). This contrasts with th e interaction of soluble ICAM-1 (sICAM-1, CD54) with human rhinovirus 3 which has been reported to have a similar affinity but 10(2)-10(3)-f old slower kinetics (Casasnovas, J. M., and Springer, T. A (1995) J. B iol. Chem. 270, 13216-13224). The extracellular portion of decay-accel erating factor comprises four short consensus repeat domains (domains 1-4) and a mucin-like stalk. By comparison of the binding affinity for echovirus 11 of various fragments of decay-accelerating factor, we ar e able to conclude that short consensus repeat domain 3 contributes si milar to 80% of the binding energy.