Enhanced transgene expression in mammalian cells by recombinant baculovirus vector containing bovine papillomavirus type 1 replication elements

Abstract

The baculovirus Autographa californica multiple nucleopolyhedrovirus has been widely explored as a transgene expression vector. Further improvement of the expression of the transgene is important for its application. Bovine papillomavirus type 1 (BPV-1) cis-element upstream regulatory region (URR) and trans-elements E1, E2, were inserted into the baculovirus genome. The expression of reporter gene, enhanced green fluorescent protein gene (EGFP), and the persistence of viral genome was compared in several mammalian cell lines after virus transduction. The cytotoxicity of the recombinant viruses was also evaluated. The recombinant baculovirus containing URR and E1, E2 genes showed significantly increased expression of EGFP in all cell lines tested, including HEK293, HeLa, BHK-21, CNE, CHO and MDCK cells. In HEK293 cells, the total production of EGFP was approximately five-fold higher than the control. The genome of virus with BPV-1 elements also persisted better than the control virus during the first few days post transduction. No obvious cytotoxicity was observed. The coexistence of BPV-1 URR and E1, E2 was essential and sufficient to improve the performance of baculovirus with respect to mediating gene expression in various mammalian cells without major cytotoxicity. The results obtained in the present study facilitate the application of baculovirus as an efficient transgene vehicle for protein production and gene delivery.