The avidity of an antibody differs from its affinity in which of the following ways?
- A Avidity refers to the strength of binding of a single antigen-binding site to one epitope
- B Avidity is the sum total of all binding strengths of a multivalent antibody interacting with multiple epitopes simultaneously ✓
- C Avidity applies only to IgG antibodies, whereas affinity applies to IgM
- D Avidity is measured by equilibrium dialysis, unlike affinity
Correct answer: B. Avidity is the sum total of all binding strengths of a multivalent antibody interacting with multiple epitopes simultaneously
Explanation
Affinity is the intrinsic binding strength at a single Fab-epitope interaction, governed by non-covalent forces. Avidity is the overall (functional) binding strength of the entire antibody molecule to its antigen, which depends on affinity, valency, and epitope accessibility. IgM, with 10 potential binding sites, has high avidity despite lower individual affinity.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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