Vaccinia Virus Gene Introduction via Marker Replacement
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Solution Overview
Problem
Current methods for introducing foreign genes into vaccinia viruses are not efficient, making it difficult to develop targeted cancer therapies that specifically kill cancer cells while sparing normal cells.
Innovation Solution
A method involving the insertion of a marker gene into the vaccinia virus followed by homologous recombination to replace it with a foreign gene, allowing for easy and confirmed introduction of therapeutic or suicide genes, such as CD and UPRT, which can selectively target and kill cancer cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods are used to introduce foreign genes into vaccinia viruses, then the process is simple, but the efficiency and confirmation of gene introduction is difficult
Solution Approach 1:
A marker gene is introduced into the vaccinia virus genome before the actual foreign gene. This preliminary action creates a detectable intermediate state that facilitates subsequent gene replacement and provides a means to confirm successful gene introduction through loss of the marker signal.
Solution Approach 2:
The marker gene serves as an intermediary element that mediates the gene introduction process. It provides a detectable signal that indicates successful viral infection and gene integration, making the otherwise difficult-to-detect foreign gene introduction confirmable through marker loss.
2Reliability
If vaccine strains of vaccinia virus are used for cancer therapy, then they are highly safe, but they retain attenuated growth potential in normal tissues requiring modification
Solution Approach 1:
The vaccinia virus genome is segmented to identify and modify specific genes (VGF and OIL) that control growth potential. By separately disrupting these genes through marker gene insertion, the virus is modified to lose growth capability in normal tissues while maintaining safety.
Solution Approach 2:
Specific modifications are made at local genomic regions (VGF and OIL genes) to alter the virus's growth properties. The marker genes are inserted at these specific locations to disrupt function locally without affecting the overall safety profile of the vaccine strain.
3Measurement precision
If marker gene is inserted first and then replaced with foreign gene, then easy and definite confirmation is achieved, but the process requires multiple steps
Solution Approach 1:
The marker gene provides a feedback signal (detectable expression) that confirms successful viral infection and gene integration. The loss of this marker signal serves as negative feedback indicating successful replacement with the foreign gene, enabling precise confirmation of the modification process.
Solution Approach 2:
The marker gene typically encodes a fluorescent protein or other detectable marker that produces a visible signal. The loss of this signal (color/fluorescence change) provides a simple visual confirmation that the gene replacement has occurred, making the process easily monitorable despite multiple steps.
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
This approach enables the efficient introduction of foreign genes into vaccinia viruses, enhancing their ability to specifically kill cancer cells through both viral oncolysis and suicide gene action, thereby improving cancer treatment efficacy.
Implementation Method 1
subsequently replaced the fluorescent marker gene with a foreign gene of interest to be introduced by homologous recombination
Implementation Method 2
Suicide genes (CD gene and UPRT gene) were introduced by the above method to the vaccinia virus wherein the fluorescent protein gene was inserted into the endogenous gene
Data Source
Figure 1A~1B
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Figure 3A~3B
AI summary
The present invention has an object to provide a vaccinia virus expressing a foreign gene and capable of killing cancer cells, and a cancer therapy drug comprising the vaccinia virus. The present invention relates to a vaccinia virus, wherein a suicide gene as a foreign gene selected from the group consisting of cytosine deaminase (CD) gene, uracil phosphoribosyltransferase (UPRT) gene, and herpes simplex virus thymidine kinase (HSV-tk) gene is introduced.