Disadvantages Protease cleavage depends upon accessibility of protease recognition site. A second purification step is needed to remove the cleaved GST from mixture. Since it relies on enzymes substrate recognition the protein must be in its native form to bind to glutathione. Uses many of the protein modification, processing and transport systems present in higher eukaryotic cells. Viral genome is large and can accommodate large segments of DNA Baculoviruses are noninfectious to vertebrates and their promoters are inactive in mammalian cells.
Life cycle makes it useful as an expression tool.
Occluded virus appears in nucleus and continues to accumulate until the cells lyse. Occluded virus particles are embedded in proteinaceous viral occlusion polyhedra within the nucleus of infected cells. Polyhedra protein is a major protein component of the occlusion bodies. Polyhedra protein needed in nature but dispensable in tissue culture cells. Nonessential for infection or replication of the virus.