Kinetics and thermodynamics of virus binding to receptor. Studies with rhinovirus, intercellular adhesion molecule-1 (ICAM-1), and surface plasmon resonance.
We have studied the kinetics and thermodynamics of a virus interacting with its receptor using human rhinovirus serotype 3 (HRV3), soluble intercellular adhesion molecule-1 (ICAM-1, CD54) containing Ig superfamily domains 1-5 (sICAM-1), and surface plasmon resonance. There were two classes of binding sites for sICAM-1 on HRV3, each comprising about 50% of the total sites, with association rate constants of 2450 +/- 300 and 134 +/- 11 M-1 s-1. These rates are low, consistent with binding to a relatively inaccessible site in the rhinovirus canyon. By contrast, three monoclonal antibodies bound to sICAM-1 with a single rate constant of 17,000-48,000 M-1 s-1. The dissociation rate constant for HRV3 was 1.7 +/- 0.1 x 10(-3) s-1, giving calculated dissociation constants of 0.7 +/- 0.1 and 12.5 +/- 1.2 microM. Agreement was good with saturation binding in solution, which showed two sites of similar abundance with KD of 0.55 +/- 0.2 and 5.7 +/- 2.0 microM. A bivalent chimera of ICAM-1 with the IgA1 Fc region bound with KD = 50 and 410 nM, showing 17-fold enhanced affinity. Lowering pH from 8.0 to 6.0 reduced affinity by approximately 50-fold, primarily by reducing the on rate. Thermodynamic measurements showed that binding of ICAM-1 to HRV3 is endothermic, by contrast to binding to monoclonal antibody. The heat that is absorbed of 3.5 and 6.3 kcal/mol for the two classes of ICAM-1 binding sites may contribute to receptor-mediated disruption of virions, which has an activation energy of about 42 kcal/mol.
Casasnovas
J M
JM
Harvard Medical School, Department of Pathology, Boston, Massachusetts 02115, USA.
Springer
T A
TA
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001704:Biopolymers; D016466:CHO Cells; D002478:Cells, Cultured; D003001:Cloning, Molecular; D006224:Cricetinae; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D007700:Kinetics; D011991:Receptors, Virus / Q000737:chemistry / Q000378:metabolism*; D012229:Rhinovirus / Q000378:metabolism*; D018411:Spodoptera; D013816:Thermodynamics
D000911:Antibodies, Monoclonal; D001704:Biopolymers; D011991:Receptors, Virus; D018799:Intercellular Adhesion Molecule-1