Comparative antirhinoviral activities of soluble intercellular adhesion molecule-1 (sICAM-1) and chimeric ICAM-1/immunoglobulin A molecule.

We conducted a comparative study of the antirhinovirus activities of soluble intercellular adhesion molecule-1 (sICAM-1) and a chimeric ICAM-1/immunoglobulin A (IgA) molecule (ICI-5D/IgA) for nine major receptor group human rhinovirus (HRV) serotypes and for a variant of HRV-39 relatively resistant to inhibition by sICAM-1. ICI-5D/IgA inhibited the infectivity of eight of the nine wild-type HRVs and the resistant HRV-39 variant and was 60 to 170 times more potent than sICAM-1 on a molar basis. In contrast to sICAM-1, ICI-5D/IgA directly neutralized the infectivity of the representative HRVs by approximately 1 log10. These results expand on the antirhinovirus spectrum of ICI-5D/IgA, confirm that dimeric forms of sICAM-1 have a higher antirhinoviral potency than monomeric sICAM-1, and indicate that cross-linking of two adjacent receptor binding sites on the virus capsid by a divalent receptor enhances the direct inactivation of viral infectivity.