Reduced virus infectivity inN. tabacum secreting a TMV-specific full-size antibody

We developed a new concept of controlling plant virus infection based on the expression and secretion of full-size antibodies in plants. The neotope-specific anti-Tobacco Mosaic Virus (anti-TMV) antibody mAb24 has a high affinity towards epitopes present only on the surface of intact tobacco mosaic virions. The infectivity of the virus is inhibited almost completely if TMV is adsorbedin vitro at ratios as low as 300 antibody molecules per virion prior to inoculation. Cloned full-size cDNAs of mAb24 heavy and light chains were integrated into the plant expression vector pSS in tandem array and used for transformation ofNicotiana tabacum. The resulting transgenic tobacco plants expressed heavy- and light-chains of mAb24 which were assembled into functional antibodies and exported to the intercellular space. TMV specificity and affinity of the plant-produced antibody (mAb24-P) was not altered when compared to the original murine mAb24. F₁ progenies segregated 3:1 with respect to antibody secretion and showed up to two-fold higher expression levels compared to the F₀ plants. Upon infection with TMV F₁ plants producing mAb24-P showed a reduction of necrotic lesion numbers which is correlated with the amount of antibody produced in transgenic plants.The nucleotide sequence data reported appear in the EMBL, GenBank and DDBJ Nucleotide Sequence Databases under the accession numbers X67210 (heavy-chain cDNA) and X67211 (light-chain cDNA).