Effect of the format of antibodies on their specificity

► Effect of the antibody format on their specificity to antigens was investigated. ► The reducing of format antibody from full-scale MAb to scFv resulted in developing of polyspecific properties. ► Reverse construction of full-size MAb from scFv base followed to specificity and affinity improvement. ► Specificity and affinity properties of antibodies were not determined by the primary source of constant antibody domain. ► ScFv within a phage particle in comparison with soluble scFv possess a greater specificity to the antigen. The influence of alterations in the format of antibodies on their specificity has been examined. To analyze the role of Ig constant regions in recognizing antigens, a comparison was made of the specificities of full-scale murine monoclonal antibodies and scFv single-chain miniantibodies obtained from the latter with regard to a group of closely related protein antigens – Staphylococcus enterotoxins. It was found that in the scFv format the specificity and affinity of miniantibodies diminished as compared to the full-scale ones. Specificity of antibodies may be enhanced by transforming them into full-scale antibodies. Moreover it was shown that miniantibodies within a phage particle generated from combinatorial phage libraries possess greater specificity to the antigen, however during the subsequent transformation to soluble scFv antibodies their specificity diminishes.