Generation and evaluation of movement protein-specific single-chain antibodies for delaying symptoms of Tomato spotted wilt virus infection in tobacco

This study investigated whether single-chain antibodies (scFvs) specific for a viral movement protein could accumulate in the plant cell cytosol and restrict viral systemic infection in plants. Nine chicken scFv fragments against the Tomato spotted wilt virus (TSWV) movement protein (NSM) were isolated by phage display. Soluble scFvs were produced in bacteria and the NSM binding activity of purified scFvs was confirmed. The nine scFv genes were cloned into a plant expression vector enabling recombinant protein accumulation in the plant cell cytosol. Immunoblot analysis demonstrated that two of the nine chicken scFvs accumulated to high levels (5.9 and 8.0% of total soluble protein). Bioassays of viral infection using transgenic tobacco plants producing NSM-specific chicken scFvs showed delayed symptom development when compared to non-transgenic control plants, indicating that expression of antibodies recognizing the TSWV movement protein is a potential strategy for generating resistant plants