Abstract
The baculovirus expression system is one of the most successful and widely used eukaryotic protein expression methods. This short review will summarise the role of bacterial artificial chromosomes (BACS) as an enabling technology for the modification of the virus genome. For many years baculovirus genomes have been maintained in E. coli as bacterial artificial chromosomes, and foreign genes have been inserted using a transposition-based system. However, with recent advances in molecular biology techniques, particularly targeting reverse engineering of the baculovirus genome by recombineering, new frontiers in protein expression are being addressed. In particular, BACs have facilitated the propagation of disabled virus genomes that allow high throughput protein expression. Furthermore, improvement in the selection of recombinant viral genomes inserted into BACS has enabled the expression of multiprotein complexes by iterative recombineering of the baculovirus genome.
Highlights
The family is divided into four genera, based on the comparison of a subset of core genes conserved between all baculoviruses [1, 2]
The viruses used for recombinant protein expression are Autographa californica multiple nucleopolyhedrosis virus(AcMNPV) and Bombyx mori nucleopolyhedrosis virus(BmNPV) and both are in the Alphabaculovirus genus
Two forms of mature virus particles are produced in infected cells: budded virus is released from the cell from about 8 hours post-infection [21, 22] and is responsible for cell-tocell spread within the infected caterpillar
Summary
Experiments in protein expression using the baculovirus genome as a vector were based on the replacement of the coding sequence for the polyhedrin protein with another gene This approach has two advantages; firstly, it capitalises on the very high expression level usually observed for polyhedrin. The first recombinant protein successfully expressed to high levels using this approach was human beta interferon [40] Subsequent modifications to this system included the insertion of the LacZ coding sequence into the polyhedrin locus of the virus genome to allow blue-white screening and linearization of the genome in an adjacent essential gene; both modifications facilitated selection of recombinant viruses [41,42,43]. These problems can be overcome to a certain extent by using modified cells engineered to express enzymes in the human glycosylation pathway [56,57,58]
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