Practice question

Double immunodiffusion developed by Ouchterlony involves diffusion of antigens and antibodies from separate wells toward each other in agar gel. Precipitin lines form at equivalence, and their fusion patterns indicate antigenic relatedness. Complete fusion suggests shared epitopes and identity, spur formation indicates partial cross-reactivity, while crossing lines denote distinct antigens. This pattern analysis makes technique ideal for comparing antisera potency, identifying strain relatedness among microbial isolates and testing antigenic similarity of toxin variants. It does not quantify hormones, detect immunoglobulin class specifically or amplify nucleic acids, which require other analytical platforms.