Avidity

Avidity designates the overall binding strength of multivalent molecules engaging multiple binding sites simultaneously, representing the cumulative effect of multiple individual interactions that collectively far exceeds simple affinities, enabling highly stable binding even when individual interactions are relatively weak.

The biopharmaceutical industry leverages avidity effects in therapeutic antibody design, vaccine development, and diagnostic assay optimisation. Bivalent IgG antibodies exhibit stronger effective binding to cell surface antigens through simultaneous engagement of two binding sites compared to equivalent monovalent fragments. Multivalent vaccine antigens presented on virus-like particles bind B cell receptors with high avidity driving strong humoral responses. Diagnostic sandwich immunoassays exploit avidity through multi-epitope antigen capture improving sensitivity. Bispecific antibodies designed to crosslink targets exploit avidity effects for T cell engagement. Understanding avidity contributions to therapeutic potency guides molecular engineering decisions for multispecific formats and delivery systems.