Antibody-mediated improved resistance to ClYVV and PVY infections in transgenic tobacco plants expressing a single-chain variable region antibody

Transgenic Nicotiana tabacum plants expressing a single-chain variable region antibody fragment derived from a broad-spectrum monoclonal antibody 3-17 showed suppression of virus infection following challenge by two distinct potyviruses: potato virus Y strain D, and clover yellow vein virus strain 300. Monoclonal antibody 3-17, which was raised against the potyvirus Johnsongrass mosaic virus, was shown to react strongly with 14 potyvirus species. Two different single-chain antibody constructs were used to produce chimeric genes encoding recombinant proteins designed to be targeted either to the apoplasm or to the cytoplasm. Transgenic plant lines showed reduced numbers of local lesions and systemic symptoms when challenged with potato virus Y, strain D and reduced local lesions following challenge with clover yellow vein virus, strain 300. The level of suppression conferred by the transgene when plants were challenged under laboratory conditions with high concentrations of virus, together with the ability of the transgene to partially protect plants against distinct viruses suggest that one single-chain gene construct might be used to protect plants from distinct potyviruses.