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. Viruses lacking the polyhedrin gene have a distinct morphology from viruses containing the gene. To use Clone gene of interest into a vector flanked 5 and 3 by polyhedrin specific sequences, co-infect with wild type viral DNA into insect cells and let homologous recombination do the rest. Baculoviruses infect invertebrates and processing is different than processing in vertebrates.