Basic methodology and genetic elements will be developed for production of biosynthetic antibody binding domains of interchangeable specificity. VH and VL domains based upon the Fv region of an anti-digoxin antibody will be refashioned to have the hypervariable segments of an anti-protein antibody. This is intended to alter its specificity without the need to remake constant framework of the Fv. This hybrid of two different murine monoclonal binding regions will be expressed in prokaryotic and eukaryotic hosts to permit purification of renatured VH,VL, and recombined Fv. Analysis of its binding properties will determine if it functions entirely as planned, and if not, computational and physicochemical studies will provide the basis for redesign. Similarly, the constant framework of a human Fv region will be used to support the binding site from a murine anti-protein monoclonal. Such intrachain, interspecies hybrids could offer unique advantages for human therapy. In particular, minimization of a human immune reaction to a murine binding site is desirable, as is utilization of murine monoclonal structural features which are experimentally accessible. Attempts will be made to fuse VH and VL genes into a single Fv gene via a linker which will be compatible with normal refolding and recombination of component domains. This single polypeptide chain binding site would be useful for immunotargeting of biologically active proteins.
