A minimum fragment of polyhedrin for higher expression of foreign proteins in a baculovirus expression system

Previously, we found that baculovirus polyhedrin fragments can be successfully used as a fusion partner for the hyper-expression of target proteins. Here, we minimized the fusion fragment of polyhedrin for higher expression of target proteins in a baculovirus expression vector system (BEVS). Recombinant viruses were generated to express enhanced green fluorescent protein (EGFP) fused with various shortened polyhedrin fragments based on the previously reported region of polyhedrin, amino acids 19 to 110. A dramatic increase in the production of EGFP was observed when polyhedrin amino acids 32 to 59 were fused with it. Additionally, this result was confirmed through the fusion of amino acids 32 to 59 with firefly luciferase and with gD of porcine Aujeszky's disease virus. However, fusion expression with ORF2 of porcine circovirus did not increase the expression efficiency and indicated that the efficiency of fusion expression with polyhedrin fragments may depend on the target protein. In conclusion, we suggest that polyhedrin amino acids 32 to 59 are a new fusion partner for hyper-enhanced production without affecting the bioactivity of target proteins in the baculovirus expression system.