A dimeric bispecific miniantibody combines two specificities with avidity

Bispecific antibodies extend the capabilities of nature and might be applied in immunotherapy and biotechnology. By fusing the gene of a single-chain Fv (scFv) fragment to a helical dimerization domain, followed by a second scFv fragment of different specificity, we were able to express a functional protein in E. coli, which is bispecific and has two valencies for each specificity, The dimeric bispecific (DiBi) miniantibody preserves the natural avidity of antibodies in a very small-sized molecule of only 120 kDa, The generality of the principle was shown with a scFv fragment binding the EGF-receptor (named scFv 425) in three combinations with scFv fragments tither directed against CD2 (ACID2.M1)? phosphorylcholine (McPC603) or fluorescein (FITC-Et). Binding mas analyzed by sandwich surface plasmon resonance biosensor (BIAcore) measurements. (C) 1998 Federation of European Biochemical Societies.