Efficient Gene Delivery Into Mammalian Cells Mediated By A Recombinant Baculovirus Containing White Spot Syndrome Virus Ie1 Promoter

As recombinant baculoviruses containing mammalian cell-active promoters are becoming a promising tool for studying gene functions and developing non-replicative vector vaccines and gene therapy strategies, a shuttle promoter that mediates gene expression in both insect cells and mammalian cells will facilitate the development of a baculovirus vector-based mammalian cell gene delivery vehicle.In this report, three recombinant baculoviruses were generated carrying the reporter EGFP gene under the control of white spot syndrome virus (WSSV) ie1 promoter, or either of two control promoters, baculovirus early to late (ETL) promoter and polyhedrin promoter. Several mammalian cell lines were transduced with the resulting recombinant baculoviruses to test the expression of EGFP. The results showed that WSSV ie1 promoter showed a strong promoter activity in insect cells and mammalian cells. The promoter activity of the ie1 promoter but not ETL promoter can be enhanced by sodium butyrate, a histone deacetylase inhibitor. Transient plasmid transfection assay indicated that ie1 promoter activity in mammalian cells is independent on baculovirus gene expression, which is different from ETL promoter, a baculovirus-dependent shuttle promoter.This study demonstrated, for the first time, that ie1 is a baculovirus-independent shuttle promoter between insect cells and mammalian cells. This novel shuttle promoter will facilitate the application of baculovirus-based vectors in gene expression, gene therapy and non-replicative vector vaccines.