Development of a novel inducible Baculovirus-Insect cell expression system

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1) Currently the Baculovirus-insect cell expression system based on the Autographa californica multinucleopolyhedro virus (AcMNPV) is widely applied to large scale protein production. This includes various fields of biological and medical research as well as the production of highly pure protein for vaccine production or of enzymes used in industrial processes.Unfortunately, effectiveness and protein yield of this system is quite often limited by toxic effects of the desired protein to the insect cells in which the actual protein expression takes place. This for example may cause an incomplete infection of the whole cell culture due to limited virus replication in already early infection stages. Therefore we intend to develop an inducible expression system which prevents expression of the protein of interest while allowing full replication and spreading of the virus within the cell culture. At the time point of induction of protein expression, all cells are therefore thought to be homogenously infected leading to a considerably higher yield.2) Moreover, this inducible system can also be applied to establish a new enhanced baculovirus-based bio-pesticide and its cost-efficient production. While currently various insect pathogenic viruses are being applied as bio-pesticides on economically relevant plants, up to now the insecticide effect is mainly caused by the overwhelming virus replication in host cells and their subsequent lysis. In order to increase pesticide efficiency, additional insect toxins could be incorporated in AcMNPV, a procedure which is also extensively applied as bio-pesticide. During large scale industrial production of such a modified virus in cell culture bioreactors, toxicity of the additional protein encoded in the viral genome would also limit virus replication and thus the yield of virus particles.This problem can be addressed by the very same inducible expression system as developed for research purposes. While during infection of the cell culture and replication of the virus, no toxic proteins are to be produced, the expression of the toxin could be triggered only on the field thus maximizing beforehand virus replication / production.3) In a second approach, we propose to apply this concept additionally to the related Cydia pomonella granulo virus (CpGV), if the beforehand described inducible expression system is effective in AcMNPV. As several already existing patents on AcMNPV are limiting cost effective usage and would also cover a modified AcMNPV, the up to now unclaimed CpGV is a reasonable alternative. In summary, the results of this project can be used in various classes of molecular / medical research as well as in the commercial sector for high yield protein production and bio pesticide development.