How the Baculovirus Expression System Works
The baculovirus expression system works by inserting the gene of interest (GOI) into the baculovirus genome under the control of a strong promoter, usually the very late POLH or p10 promoter. These promoters drive high-level expression of viral proteins only at late times post-infection. The recombinant baculovirus is then used to infect insect cell cultures. As the virus replicates inside the cells, it directs the cellular machinery to mass-produce the inserted recombinant protein along with other viral proteins. The recombinant protein of interest can then be purified from the infected cell culture supernatant or pellet.

Key Advantages of Baculovirus Expression System
Some major advantages of the Baculovirus Expression System include its ability to express functionally active eukaryotic proteins with proper post-translational modifications like glycosylation. Proteins can be expressed at very high levels, typically 1-10 mg/L of culture. Scale-up is easy using suspension cultures in bioreactors. The system is safe since baculoviruses do not replicate in mammalian cells. Finally, insect cells tolerate difficult-to-express proteins better than bacterial or yeast systems.

Applications of the Baculovirus System
Due to its advantages, the baculovirus system is widely used for production of various therapeutics, vaccines, and research proteins. Some examples are discussed below:

Therapeutic Protein Production
Many FDA-approved recombinant therapeutics produced in baculovirus include recombinant human interferon proteins and erythropoietin. Additionally, viral antigens for vaccines and monoclonal antibodies are also manufactured using this system. Recent work demonstrated the commercial production of biosimilar versions of blockbuster antibodies like bevacizumab and cetuximab in insect cells.

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