PCV2 Capsid-IBD Fusion VLPs for Stable E. Coli Vaccine Production
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Solution Overview
Problem
Existing PCV2 vaccines face challenges such as low virus titer in cultured cells, high production costs, molecular instability under physicochemical stress, and insoluble protein aggregates in Escherichia coli expression systems, making stable VLP formation difficult.
Innovation Solution
A fusion protein of PCV2 capsid protein (Cap) and immunoglobulin-binding domain (IBD) is expressed in Escherichia coli, allowing spontaneous VLP formation with enhanced molecular stability and stability against physicochemical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If PCV2 Cap is produced using traditional expression systems (baculovirus/insect cell), then the VLP can be formed, but the production cost increases and work complexity increases
Solution Approach 1:
The patent uses Escherichia coli, a simple and inexpensive bacterial expression system, instead of complex and expensive baculovirus/insect cell systems. The E. coli system allows for cost-effective production of Cap protein while maintaining the ability to form VLPs, directly addressing the contradiction between production cost and productivity
Solution Approach 2:
The patent modifies the Cap protein by fusing it with an immunoglobulin-binding domain (IBD), changing the molecular parameters of the protein. This modification enables the Cap to be produced solubly in E. coli and facilitates spontaneous VLP formation, thereby achieving high productivity with a simple expression system
2Ease of manufacture
If PCV2 Cap is produced in Escherichia coli expression system, then the production cost decreases, but the protein forms insoluble aggregates (inclusion bodies)
Solution Approach 1:
The patent introduces an immunoglobulin-binding domain (IBD) as an intermediary component fused to the Cap protein. This IBD acts as a mediator that prevents the Cap from forming insoluble inclusion bodies in E. coli, while allowing the modified Cap to be produced in large quantities as soluble protein
Solution Approach 2:
The patent creates a composite protein structure by fusing Cap with IBD to form a Cap-IBD fusion protein. This composite structure combines the antigenic properties of Cap with the solubility-enhancing properties of IBD, enabling cost-effective production without inclusion body formation
3Productivity
If VLP is formed from Cap produced in baculovirus/insect cell system, then the VLP can be formed, but the molecular stability against physicochemical load decreases
Solution Approach 1:
The patent uses E. coli-produced Cap-IBD fusion protein instead of baculovirus/insect cell-produced Cap. The bacterial expression system produces a more stable protein that forms VLPs with superior resistance to heat treatment and long-term storage, reversing the stability problem associated with traditional systems
4Productivity
If traditional Cap production methods are used, then the VLP can be produced, but complex post-treatment processes are required
Solution Approach 1:
The Cap-IBD fusion protein has the inherent ability to spontaneously self-assemble into VLPs without requiring complex post-treatment processes. The IBD component facilitates proper folding and assembly, allowing the protein to self-organize into functional VLPs directly from the expression system
Solution Approach 2:
The patent extracts and utilizes the spontaneous self-assembly property of the Cap-IBD fusion protein, eliminating the need for complex purification and assembly procedures required by traditional Cap production methods. This simplifies the entire production workflow while maintaining VLP quality
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The Cap-IBD fusion protein forms stable VLPs that maintain their shape and function as effective vaccines, providing high molecular stability and ease of production without complex post-treatment processes.
Implementation Method 1
a fusion protein of PCV2 Cap and IBD (Cap-IBD fusion protein) is capable of spontaneously associating in the cytoplasm of an Escherichia coli expression host and forming VLP
Data Source
AI summary
Provided is PCV2 VLP that can be used as a vaccine for use in the field of animal husbandry and that has high molecular stability against physicochemical load. A fusion protein according to the present invention includes a capsid protein of porcine circovirus type 2 and an immunoglobulin-binding domain.