Non-diffusing Plant Virus Vector for Controlled Gene Expression
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Solution Overview
Problem
Existing plant virus vectors establish uncontrolled infections in host plants, leading to unintended diffusion of recombinant virus genes and high risks of transmission through soil-borne, insect-borne, and direct-contact routes.
Innovation Solution
Development of a non-diffusing plant virus vector lacking the gene involved in intercellular movement, specifically a cucumber mosaic virus (CMV) vector with a stop codon inserted in the RNA-3 gene encoding the 3a protein, which only proliferates in transgenic plants expressing the necessary protein for intercellular movement, preventing uncontrolled spread.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a plant virus vector is used to express foreign genes, then gene expression capability is improved, but uncontrolled diffusion and transmission risk increases
Solution Approach 1:
The patent extracts and removes the movement protein (MP) gene from the virus vector genome, separating the gene expression function from the intercellular movement function. This creates a vector that can express foreign genes but cannot move between cells autonomously, directly resolving the contradiction between expression capability and diffusion risk.
Solution Approach 2:
The patent introduces a complementation system where the MP gene is provided by a separate helper component or transgenic plant. This intermediary approach allows the virus vector to regain movement capability only when paired with the appropriate complementing element, enabling controlled gene expression while preventing uncontrolled diffusion through soil-borne, insect-borne, and direct-contact transmission.
2Object-affected harmful factors
If the virus vector is made non-diffusing by removing the movement protein gene, then transmission risk is reduced, but intercellular movement capability is lost
Solution Approach 1:
The patent segments the virus vector into separate functional components: one vector carries the foreign gene expression cassette but lacks the MP gene, while another component (helper virus or transgenic plant) provides the MP gene. This segmentation allows independent control of gene expression and intercellular movement functions, resolving the contradiction between reducing transmission risk and maintaining movement capability.
Solution Approach 2:
The patent employs preliminary action by pre-transfecting plants with the MP gene or providing a helper component before introducing the virus vector. This ensures that when the vector enters the plant, the necessary movement protein is already available, enabling intercellular movement without requiring the vector to carry the MP gene itself, thus reducing transmission risk while maintaining movement capability.
3Reliability
If a CMV vector with stop codon in RNA-3 gene is used, then selective infection in transgenic plants is achieved, but proliferation in normal plants is prevented
Solution Approach 1:
The patent applies local quality by introducing a stop codon specifically in the RNA-3 gene region that encodes the movement protein, while leaving other essential viral genes intact. This localized modification prevents proliferation in normal plants by blocking movement protein production, but allows selective infection and proliferation in transgenic plants that provide complementary movement functions through their modified genomes.
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AI summary
The present invention is to provide a novel non-diffusing plant virus vector wherein virus vector infection and proliferation are possible only in a recombinant plant transfected with a gene necessary for viral proliferation, thereby enabling avoidance of unintended diffusion of a recombinant virus, a selective and specific expression system therefor, and a method of expression thereof which comprises combining a non-diffusing virus vector lacking a gene involved in intercellular movement of a cucumber mosaic virus (CMV) genome and a transgenic plant transfected with the lacked gene involved in intercellular movement for the non-diffusing virus vector to establish infection and proliferation selectively and specifically in the transgenic plant.