INDUCTION OF ANTIBODIES TO PLANT VIRAL-PROTEINS BY DNA-BASED IMMUNIZATION

DNA-based immunization is a promising new technique for generating ant ibodies in laboratory animals for diagnostic purposes in biological sc ience. The main advantages are the elimination of time and labor and t he technically demanding steps of antigen purification. The DNA sequen ce of the protein of interest, cloned in a suitable in vivo expression vector that is administered intramuscularly or intradermally, is suff icient to induce an immune response in animals. We report the inductio n of antibodies to tobacco mosaic virus (TMV) coat protein (CP) as a h ighly immunogenic structural protein and potato virus Y (PVY) P1 prote in (P1) as a nonstructural protein. The appropriate nucleotide sequenc es were introduced in a mammalian expression vector (pSG5) and injecte d intramuscularly into New Zealand White rabbits (Oryctolagus cuniculu s). By 10 days post-injection (dpi) a specific immune response was det ected against TMV-CP, while it took about 5 weeks for a response to PV Y P1. In both cases the antibody titers were significantly above the c orresponding pre-immune serum, however, they were considerably below t he titer of the matching conventionally produced antiserum. To our kno wledge, this is the first report of DNA-based immunization in order to generate antibodies to plant viral proteins, but further improvements are necessary to increase antibody titers before this promising new t echnique can be introduced broadly in plant science for diagnostic pur poses. (C) 1997 Elsevier Science B.V.