The Exploration of Fibronectins Evolved by mRNA Display Selection as Novel Alternatives to Antibodies

Antibodies naturally help the immune system fight off infections, but they have also become powerful tools for biological research. A major drawback, however, is that antibody production is both time-consuming and expensive. mRNA display selection is an in vitro high-throughput screening technique that can rapidly evolve antibody-like molecules, bypassing the immune response that is required to generate antibodies. Novel, antibody-like fibronectins, with targets ranging from human interleukin-6 to the nucleocapsid protein of the severe acute respiratory syndrome coronavirus, were rapidly evolved by mRNA display selection. These fibronectins have been shown to function like antibodies in vivo, and their ability to also capture and detect their targets in vitro will be demonstrated in enzyme-linked immunosorbent assays (ELISAs) and western blots. Bacterial expression vectors with conjugations to alkaline phosphatase and horseradish peroxidase were designed, and the protein-fusion constructs were expressed and purified. Conditions that will optimize the performance of the evolved fibronectins on ELISAs and western blots are being explored. The ability to rapidly generate antibody-like molecules would have far-reaching implications in research, from basic molecular biology to therapeutics and diagnostics.