Generation of chimeric baculovirus with histidine-tags displayed on the envelope and its purification using immobilized metal affinity chromatography

Baculovirus/insect cell system has been widely used for recombinant protein production. Since the finding that baculovirus is capable of transducing hepatocytes in 1995, success to utilize baculovirus as a gene delivery vehicle into mammalian cells has been reported. Due to the high transduction efficiency and the non-replication nature in mammalian cells, baculovirus has emerged as a vector for in vivo gene therapy. For gene therapy studies and future clinical needs, a simple and efficient purification scheme for baculovirus is necessary. In this study, a recombinant baculovirus with a hexahistidine (His6) tag fused on the viral envelope protein, gp64, was constructed. The presence of the His6-tagged gp64 was confirmed by Western blot and its display on the virus surface was visualized by immunogold electron microscopy. The His6 tag displayed on the virus surface enabled the virus purification by a simple immobilized metal affinity chromatography (IMAC) with high purity (≈87%), thus obviating the need for successive ultracentrifugation steps. The recovery yield was higher than that obtained in conventional gradient ultracentrifugation but necessitated further process improvement. This study demonstrates the feasibility of combining the baculoviral display technology and IMAC for viral vector purification.