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Baculovirus Expression Vector System

2020-12-01
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Overview of Protein Expression System

In 1983, two sample groups expressed eukaryotic genes in the colon (Harris et al., 1983; Wetzel and Goeddel, 1983). Its genetics, biochemistry and molecular biology have been well understood, so it is the preferred system for the expression of many foreign proteins. The biggest feature of the Escherichia coli expression system is low culture cost, strong tolerance, and high efficiency. The advantage of the Bacillus subtilis expression system is that the target protein can be secreted into the culture medium in a soluble active form with high yield, but it is expressed in the protein During the process, Bacillus subtilis will secrete some proteins to degrade the target protein, and the expression level of this system is often lower than that of the antibiotic expression system.

Currently commonly used eukaryotic expression systems are: mammalian cell expression system, yeast expression system and baculovirus expression system (also called insect cell expression system). The mammalian expression system has many advantages: (1) the expressed protein can be post-translationally modified and folded correctly; (2) the target protein can be expressed constitutively or inductively; (3) the target protein can also be expressed in the form of transgene (Colosimo Et al. 2000). However, mammalian expression systems have slower expression speeds and higher costs, and are not suitable for large-scale protein production. The yeast expression system mainly uses Saccharomyces cerevisiae and Pichia pastoris. The advantages of yeast expression system are mainly in two aspects. It is that the target protein expressed by yeast is first in yeast cells, and then secreted into the culture medium through the secretion system of yeast to obtain folded and modified proteins (Byrne et al. 2005) However, the glycosylation of proteins in yeast cells is different from the glycosylation of natural proteins in mammals. Therefore, when the glycosylation of the target protein is the key to maintaining protein activity, the yeast expression system (Higgins) should not be selected. Et al. 1998). Another disadvantage of the yeast expression system is that the expression efficiency of most recombinant proteins in this system is reduced. Compared with several other systems, baculovirus/insect cell (BEVS, baculovirus expression vector system) is a relatively compromised protein expression system (below):

Baculovirus Expression System
Comparison of several expression systems

The Advantages of Baculovirus as a Foreign Gene Expression Vector Mainly Include the Following Aspects:

(1) Easy to operate. Baculovirus has a small genome, simple molecular biological characteristics, and a variety of endonuclease cut sites on the genome.

(2) Large foreign genes can be accommodated. The virion of baculovirus is rod-shaped, and its plasticity is relatively strong to accommodate foreign genes. In theory, it can accommodate any foreign genes.

(3) It can express foreign genes efficiently. Among baculovirus genes, p10 gene and polyhedrin gene are extremely late genes, and their promoters can efficiently express the target protein.

(4) The target protein can be modified after expression. The host of baculovirus is insect cells, and the target protein can be processed and modified using the post-translational modification system of insect cells.

(5) High security. The baculovirus expression vector itself is very strong and can only replicate in insect cells.

(6) Low cost. Compared with mammalian cells, insect cultured cell lines are relatively easier to grow, and insect cells can be cultured in suspension to produce large amounts of the target protein.

However, baculovirus expression vectors also have some disadvantages. The baculovirus-insect cell expression system is a transient expression system. In addition, the promoter of the baculovirus expression vector is a late promoter. The expression time limit is 22-24 hours after infection. Insect cells generally do not provide complex N-glycosylation. Although this type of N-glycosylation generally provides a protein product that provides biological activity, the end lacks complexity. In addition, the high level of baculovirus expression of protein will cause the speed of post-translational modification of cells to keep up with the speed of expression, which may reduce the production of post-expression modified proteins. , Baculovirus-insect cell expression system has been widely used in human health, medicine, agriculture and other fields.

Medicilon’s Baculovirus Expression Vector System

Medicilon researchers establish a well-developed baculovirus-insect cell expression services platform. We provide the expression and purification services on preparation of recombinant baculovirus and recombinant protein. We have a good track record in producing kinase and recombinant protein complexes.

Baculovirus Expression Vector System Service:

  1. Generation of recombinant Bacmid DNA

  2. Preparation of recombinant baculovirus

  3. Titration of baculovirus

  4. Protein expression verification and optimization

  5. Small scale expression and purification of recombinant protein in insect cell

  6. Scale up expression and purification of recombinant protein in insect cell

StepsItemsTimelineComments
1Generation of recombinant Bacmid DNA3 weeksDifferent affinity tag: GST tag, His tag, Flag tag…..
2Preparation of recombinant baculovirus2 weeks
3Titration of baculovirus2-3 daysQuantitative-PCR or based on gp64 antibody
4Protein expression verification and optimization2 weeksMOIs, PIs or different cell lines
5Small scale expression and purification2-4 weeks500 ml-2L expression in flask
6Scale up expression and purificationTBDCulture in flask or fermentor

Related Articles:

Baculovirus Expression System

Baculovirus Expression System (Also Called Insect Cell Expression System)

Introduction of Bac-to-Bac System

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