Viral hemorrhagic septicemia virus glycoprotein production in tobacco

Viral hemorrhagic septicemia virus (VHSV) causes mortality in numerous marine and freshwater fish species resulting in heavy losses in fish farming. The glycoprotein gene of VHSV was fused with the cholera toxin B subunit (CTB) and expressed transiently in leaf tissues of Nicotiana benthamiana via the agroinfiltration method. The glycoprotein gene was divided into two parts to improve assembly of CTB fusion proteins (CTB-VHSV_99-235 and CTB-VHSV_258-417). Production of CTB fusion proteins was confirmed in the agroinfiltrated leaf tissue by western blot analysis. The plant-produced CTB fusion proteins showed biological activity to G_M1-ganglioside, a receptor for biologically active CTB, on G_M1-ELISA. The expression level of the CTB-VHSV fusion proteins was 0.86% (CTB-VHSV_99-235) and 0.93% (CTB-VHSV_258-417) of total proteins in agroinfiltrated leaf tissue, as determined by G_M1-ELISA. These results suggest that Agrobacterium-mediated transient expression of CTB fusion antigens of VHSV is a rapid and convenient method and demonstrate the feasibility of using agroinfiltrated plant leaf tissues expressing CTB-fusion antigens as a plant-based vaccine to prevent VHSV infection.