flashBAC Manual - Oxford Expression Technologies

7.2 The baculovirus expression systemThe baculovirus polyhedrin gene is non-essential for virusreplication in insect cells and this has led to the development ofthe widely-used baculovirus expression vector system, firstdescribed by Smith et al. 3 . The coding sequences of thepolyhedrin gene are replaced by those of a foreign gene, toproduce a recombinant baculovirus in which the powerfulpolyhedrin promoter drives expression of the foreign gene.Hence recombinant baculoviruses are sometimes referred to aspolyhedrin/polyhedra-negative viruses.Expression of foreign genes in insect cells using recombinantbaculoviruses has become one of the most widely usedexpression systems, and is often the first choice eukaryoticsystem.The baculovirus expression system has severaladvantages over bacterial systems:• Safe to use.• Can accommodate large or multiple genes• Uses a variety of promoters for early and/or late geneexpression• Uses very efficient gene promoters• Proteins produced are almost always functional• Proteins are processed: signal peptide cleavage, nucleartargeting, membrane targeting, secretion, phosphorylation,glycosylation, acylationHowever, it is not without its disadvantages and these lie mainlyin the labour-intensive and technically demanding steps neededto produce recombinant viruses. The following outlines theOXFORD EXPRESSION TECHNOLOGIES 12