Transgenic plants for the production of veterinary vaccines

DUS SANTOS MJ; GOMEZ C; MOZGOVOJ M; CHIAVENNA S; RIOS R; ARDILA F; WIGDOROVITZ A

BUENOS AIRES

Congreso; VIII CONGRESO ARGENTINO DE VIROLOGIA; 2005

SAV

The expression of antigens in transgenic plants has been increasingly used in the development of experimental vaccines, particularly oriented to the possibility of development of edible vaccines. Hence, this technology becomes highly suitable to express immunogenic proteins from enteric pathogens. Rotavirus (RV), Bovine Viral Diarrhoea virus (BVDV) and Foot and Mouth Disease Virus (FMDV) are considered to be the most important causative agent of economic loss of cattle production activity in Argentina and thus, constitute optimal candidates for the obtainment of alternative sources of immunization tools. Here, we present the development of different experimental immunogens of these viruses through the expression of immunogenic proteins from these viruses in alfalfa transgenic plants. Bovine rotavirus epitope eBRV4 has been described as harbouring at least one neutralizing epitope as well as to be responsible for the adsorption of the virus to the epithelial cells. We produce transgenic alfalfa plants expressing the chimerical protein eBRV4-âGUS. The plants were produced and efficiently selected based on their levels of âGUS enzymatic activity, a result further confirmed by western blot assays specific for the BRV peptide. The eBRV4 epitope expressed in plants was effective in inducing anti-rotavirus antibody response in adult female mice when administered either intraperitoneally or orally and, importantly, suckling mice born from immunized female mice were protected against the oral challenge with virulent rotavirus. Inactivated BVDV vaccines are usually inefficient in inducing strong immunity, so the use of recombinant subunit vaccines has been proposed as an alternative to solve this difficulty.  We report here the development of transgenic plants of alfalfa expressing the structural protein E2 of BVDV. The presence of the transgenes in the plants was confirmed by PCR and their expression was demonstrated by RT-PCR, western blot and ELISA. Current FMDV vaccines are based on the utilization of inactivated virus and, although they have proved to be effective tools for the prevention of the disease, their production is both costly and risky because of manipulation of massive amounts of virulent virus which could result in virus dissemination. In this study, we propose the utilization of Cassava vein mosaic virus (CsVMV) promoter with the aim of increasing FMDV polyprotein P1 (precursor of the viral structural proteins) expression in alfalfa plants. The presence of P1 was determinated by western blot and ELISA assays. The obtained results demonstrated that CsVMV promoter shows a better performance than 35S promoter for the expression of FMDV P1 in leaves transgenic alfalfa plants. The results presented here confirm the possibility of using plants as antigen expression vectors that could be directly applied for the development of plant-based vaccines.