Baculovirus-Insect Expression System

Insect cells in combination with the baculovirus expression system are gaining widespread uses as a versatile eukaryotic expression system for antibody production. Creative Biolabs has abundant experience in the baculovirus-insect expression system. We have successfully developed several transfer plasmids, enhanced insect cell lines to aid antibody expression.

The baculovirus-insect expression system is used based on the ability that insect cells can be efficiently transfected with insect-specific viruses from the family of Baculoviridae, particularly the Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV). The heterologous antibodies can be produced both in insect cells and larvae. Baculoviruses are highly species-specific and are considered as safe for vertebrates, and its promoters are inactive in mammalian cells. Those non-essential baculovirus genes involved in the viral life cycle, for instance, Polyhedrin, P10, or Basic, can be replaced by heterologous genes to produce interested antibodies. As the highly flexible nature of viral envelope, it allows packaging of large heterologous gene sequences of more than 20 kb.

The main insect cell lines used for antibody expression are Spodoptera frugiperda (SF), Drosophila melanogaster and Trichoplusia ni. Creative Biolabs provides available insect cell lines of Sf9, Sf21 of Spodoptera frugiperda, DS2 cells of Drosophila melanogaster and Hi-5 cells of Trichoplusia ni according to different needs. Sf-9 and Sf-21 cells are recommended for producing high-titer viral stocks due to higher transfection efficiency, and Hi-5 cells can be used to secrete up to 25-fold higher protein levels.

Baculovirus system can be performed in small-scale using plates or shake flasks as well as in large scale using Spinner flasks or bioreactors. After up to 96 h production length, production yields of 6-18 mg/L have been achieved for various IgGs.

The steps of baculovirus protein expression service including:

• Clone target gene in a bacterial shuttle vector
• Selection and expansion of positive clones
• Isolate of shuttle vector
• AcMNPV and shuttle vector cotransfecting insect cells
• Homologous recombination is taken place to get recombinant virus
• Production of high-titer recombinant virus stock
• Recombinant virus used to infect new insect cells followed by protein purification

Figure 1. Insect cell expression systems

The advantages of using baculovirus expression system over E. coli system are obvious, such as improved solubility and post-translational modifications available. We strongly recommend our baculovirus expression system to the customers who prefer a eukaryotic expression system, exploring lower-cost alternatives to mammalian expression system but do not want to compromise on the overall quality of their recombinant protein.

The advantages including:

• Majority of post-translational modifications found in mammalian cells, such as proper folding and S-S bond formation, are available
• Relatively high yield of recombinant protein during the last phases of lytic cycle before cell lysis
• Able to express multiple genes of interest at the same time from a single bi- or polycistronic vector
• Suitable to generate both cytoplasmic and secreted proteins

Using our baculovirus expression system we can establish the best possible protocol for your custom project and then scale up to get the highest expression of your target protein. We are happy to give advice regarding the appropriate construct for your purpose.

For more detailed information, please feel free to contact us or directly sent us an inquiry.

Reference

1. Frenzel A, Hust M and Schirrmann T (2013) “Expression of Recombinant Antibodies” Front Immunol 4: 217.

For Research Use Only.