Truncated EBNA1 Vector System for CHO Cell Transfection Efficiency
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Solution Overview
Problem
Large-scale transfection of Chinese Hamster Ovary (CHO) cells for protein production is inefficient and not cost-effective, with existing plasmid vectors not fully optimized for transient gene expression, and temperature shifts to enhance productivity are not user-friendly, especially in non-refrigerated systems.
Innovation Solution
An expression system comprising a first vector with an EBNA1 nucleotide sequence and an oriP sequence, and a second vector with a gene of interest and an oriP sequence, allowing for stable expression and enhanced productivity through the use of truncated EBNA1 proteins and optimized promoters, with the option of single or two-vector systems for CHO and HEK293 cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional plasmid vectors are used for transfection of CHO cells, then the process is simple and cost-effective, but transfection efficiency and productivity are low
Solution Approach 1:
The patent divides the expression system into two separate vectors: one containing the EBNA1 gene construct and another containing the gene of interest with oriP sequence. This segmentation allows each vector to be optimized for its specific function while maintaining overall system effectiveness for stable episomal expression in CHO cells
Solution Approach 2:
The patent introduces EBNA1 protein as an intermediary that enables episomal maintenance and expression of the gene of interest vector. EBNA1 acts as a mediator that recognizes the oriP sequence and facilitates stable expression without integration into the host genome, thereby improving transfection efficiency
2Productivity
If temperature shift is applied to enhance productivity, then protein production is enhanced, but the operation becomes complex and not user-friendly
Solution Approach 1:
The patent employs temperature-insensitive promoters (EF1α-HTLV and RSV) that drive gene expression without requiring temperature shifts. The expression system is self-sufficient and maintains stable expression across a range of temperatures, eliminating the need for complex temperature control protocols and making the system user-friendly for large-scale applications
3Productivity
If full length EBNA1 is used, then the expression system is established, but the expression levels are lower compared to truncated forms
Solution Approach 1:
The patent uses truncated forms of EBNA1 (EBNA1c, EBNA1t, EBNA1s) that contain only the essential functional domains required for oriP recognition and episomal maintenance. By removing non-essential regions, the truncated forms achieve higher expression levels and improved transfection efficiency while simplifying the overall vector design
Data Source
AI summary
An expression system for stable expression of a gene of interest is described, the expression system comprising: a first vector having an Epstein-Barr virus nuclear antigen-1 (EBNA1) nucleotide sequence encoding a truncated EBNA1 protein, a promoter and a polyadenylation signal for the EBNA1 nucleotide sequence and an oriP nucleotide sequence; and, a second vector having a gene of interest, a promoter and a polyadenylation signal for the gene of interest and an oriP nucleotide sequence.