Abstract: Giant panda rotavirus (GPRV) is the main cause of diarrhea in young giant pandas, and it has a great harm to captive giant pandas. The rotavirus structural protein VP6 is a carrier protein that mediates mucosal immune responses, and VP7 is the major neutralizing antigen in rotavirus structural proteins. Therefore, the fusion expression of VP6-VP7 as a candidate antigen has important significance for the prevention and treatment of this disease. However, the prokaryotic expression of traditional E. coli has the disadvantages of low expression, poor solubility and low purity. In this study, three kinds of fusion tags, aldolase (EDA), glutathione S-transferase (GST) and maltose-binding protein (MBP), were used to obtain GPRV-VP6-VP7 protein with high expression and high purity. The VP6 and VP7 genes were constructed by homologous recombination into the expression vector pET21b containing three kinds of facilitating tags, and the recombinant plasmid was transformed into E. coli Rosetta (DE3) competent cells for low temperature induction. The target protein was purified by Ni-column affinity chromatography, and the protein expression was analyzed by SDS-PAGE and Image J. Western blot analysis showed that the recombinant protein was correct and had activity of protein. The experimental results showed that the EDA tag could significantly promote the prokaryotic soluble expression of VP6-VP7 protein and increase the expression of VP6-VP7 protein.

Key words: giant panda rotavirus(GPRV), VP6-VP7 protein, fusion tag, aldolase