Evaluation of different expression systems for the heterologous production of sprivivirus glycoprotein.
Glycoprotein mediated the entry of rhabdoviruses into the host cell and was the target of neutralizing antibodies. It was a prime tool for the study of the evolution and pathogenesis of viruses. Here, four different expression systems including cell-free synthesis system, Escherichia coli, Pichia pastoris and the baculovirus infected Spodoptera frugiperda were used to explore the recombinant expression of spring viraemia of carp virus glycoprotein. The results indicated that the recombinant glycoprotein could be detected in E. coli cell-free system after in vitro incubation for 16 h at 25°C. E. coli was found to be the optimal expression system for the production of the largest amount of recombinant glycoprotein. Although robust yields were considerable in E. coli, the formation of insoluble aggregates and the removal of solubilizing labels were challenging for the expression and purification of glycoprotein. For this reason, the higher eukaryotic expression systems, yeast GS115 and insect Sf9 cells were used for the production of glycoprotein. The purity of the recombinant protein obtained from yeast culture was over 90% after purification by Ni-NTA. In insect cells, the target protein was expressed mainly in the intracellular environment, but secretory glycoprotein was also detected by western blotting. These findings provided a basis for further investigations into the structure and function of SVCV glycoprotein.