Bacterial Expression and Characterization of a Single-Chain Variable Fragment Antibody Specific to Several Replicases of Plant (+)RNA Viruses

The use of synthetic antibodies may be an alternative tool for plant protection. RNA-dependent RNA polymerases (RdRps) play a key role in the process of virus replication. If recombinant antibodies like singlechain variable fragment antibodies (scFv) are directed against RdRps, they might be used to create virusresistant plants. To this end, a recombinant antibody from a phage display library directed against the conserved amino acid domain (glycine-aspartate-aspartate, GDD) in the active centre of the RdRp of plant (+)RNA viruses was selected. High expression level in Escherichia coli enabled the purification of scFv which was used to raise polyclonal anti-scFv antibodies. The scFv was characterized and assessed for specificity to the RdRps of viruses belonging to different families. It reacted with the RdRps of numerous distinct viruses, showing its potential in generating resistance to a large number of (+)RNA viruses containing the GDD motif