Improved detection of Beet necrotic yellow vein virus in a DAS ELISA by means of antibody single chain fragments (scFv) which were selected to protease-stable epitopes from phage display libraries

The detection of Beer necrotic yellow vein virus (BNYVV) in stored sugar be ets by means of monoclonal antibodies or antibody single chain fragments (s cFv) often poses problems, because the immunodominant C-terminal epitope of the viral coat protein is readily lost due to proteolysis. Clones which pr oduce scFv specific for protease-stable BNYVV epitopes were selected from t wo naive phage display libraries. Fusion proteins of the scFv with a human IgG kappa chain (expressed from the newly designed vector pCL) or with alh- aline phosphatase, respectively, allow the ELISA detection of BNYVV even in stored sugar beets with a sensitivity which was comparable or often higher than that achieved with polyclonal antibodies.