Insect baculoviruses

The insect baculovirus-cell system has been widely used, mainly for the production of recombinant proteins (Maiorella et al., 1988 Jarvis, 1997). This system has several advantages, including the ability to produce functional recombinant proteins that are immunogenically active, the ability to make post-translation modifications, and the fact that it contains a powerful promoter (polyhedrin), as well as the fact that the virus is not pathogenic to plants and vertebrates (Caron et al., 1990 Nguyen et al., 1993 Godwin et al., 1996). 

The BEV is a helper independent DNA virus expression vector which replicates in insects or insect cells (28-30). Insect baculoviruses are reported mostly horn insect arthropods, but a few are also known from non-insect arthropods (31 9). 

Miller, L.K. (1989) Insect baculoviruses powerful gene expression vectors. Bioessays 11 91-95. 

Miller, L. K. Insect baculoviruses powerfijl gene expression vectors. Bioessays 1989, 77(4), 91-95. 

A number of allergens from both honey bee and vespid venoms have been cloned and expressed by either Escherichia coli or baculovirus-infected insect cells (table 1) phospholipase Aj [20], hyaluronidase [21], acid phosphatase [13] and Api m6 [14] from honey bee venom, as well as antigen 5 [22], phospholipase A and hyaluronidase [23] from vespid venom, and dipeptidylpeptidases from both bee and Vespula venoms [15, 16]. Their reactivity with human-specific IgE antibodies to the respective allergens has been documented [11-16, 22, 23] and their specificity is superior... 

Andersen, J.N., "Temperature Effect on Recombinant Protein Production Using a Baculovirus/Insect Cell Expression System", Diploma Thesis, University of Calgary and Technical University of Denmark, 1995. 

Insect cell systems represent multiple advantages compared with mammalian cell cultures (1) they are easier to handle (Table 2.1) (2) cultivation media are usually cheaper (3) they need only minimum safety precautions, as baculovirus is harmless for humans (4) they provide most higher eukaryotic posttranslational modifications and heterologous eukaryotic proteins are usually obtained in their native conformation (5) the baculovirus system is easily scalable to the bioreactor scale. However, because of the viral nature of the system, continuous fermentation for transient expression is not possible - the cells finally die. 

Zhang, F., Saarinen, M.A., Itle, L.J. et al. (2002) The effect of dissolved oxygen (DO) concentration on the glycosylation of recombinant protein produced by the insect cell-baculovirus expression system. Biotechnology and Bioengineering, 11 (2), 219-224. 

Philipps, B., Forstner, M. and Mayr, L.M. (2005) A baculovirus expression vector system for simultaneous protein expression in insect and mammalian cells. Biotechnology Progress, 21 (3), 708-711. 

Kost, T.A., Condreay, J.P. and Jarvis, D.L. (2005) Baculovirus as versatile vectors for protein expression in insect and mammalian cells. Nature Biotechnology, 23 (5), 567-575. 

Jarvis, D.L. (2003) Developing baculovirus-insect cell expression systems for humanized recombinant glycoprotein production. Virology, 310 (1), 1-7. 

Co-expression of the human a- and p-subunits in the yeast Pichea pastoralis produces only trace amounts of active tetramer, with the majority being present in an unassembled form. Co-expression with human type III collagens, however, increases this assembly level tenfold. This indicates that collagen synthesis and the formation of an active prolyl 4-hydroxylase complex are mutually dependent processes (Vuorela et al, 1997). A similar observation has been noted for baculovirus encoded enzymes in insect cells (Lamberg et al, 1996). These findings support the hypothesis that this unusual control mechanism may be a common feature of collagen synthesis in all cell types. 

A wide range of proteins have been produced at laboratory scale in recombinant insect cell culture systems. The approach generally entails the infection of cultured insect cells with an engineered baculovirus (viral family that naturally infect insects) carrying the gene coding for the desired protein placed under the influence of a powerful viral promoter. Amongst the systems most commonly employed are ... 

Baculovirus/insect cell-based systems are cited as having a number of advantages, including ... 

Baculovirus Improved procedure Infection of insect cells High expression yields Relatively slow virus production Different post-translational processing... 

Post-translational modifications, such as phosphorylation, complex glycosylation, and lipidation, typically occur in eukaryotic organisms. Therefore, their expression in prokaryotic systems like Escherichia coli is difficult. However, it should be noted that via clever engineering and coexpression of specific enzymes, access can be granted to specific lipidated proteins via expression in bacteria, for example, via the expression of A -myristoyltransferase in E. coli Eukaryotic systems that can be used for the expression of post-translationally modified proteins are yeast and Dictyostelium discoidum. Furthermore, lipidated proteins, such as the Rah proteins, can be obtained via purification from tissue sources or from membrane fractions of insect cells that had been infected with baculovirus bearing a Rah gene. ... 

Members of the Caliciviridae family can hardly be examined in cell culture or animal models. Therefore, so-called virus-Hke particles (VLP) are employed in current experiments. These particles are expressed recombinantly in insect cells using a baculovirus system and do not carry infectious viral RNA [70-72]. It has been shown by single particle tracking studies that VLPs are internalized into the cells in a similar fashion to native viruses [73]. VLPs are believed to present identical molecular recognition elements to the outside world as do native viruses. 

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