Altered Lentiviral Integrase for Site-Specific Genome Insertion
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Solution Overview
Problem
Existing methods for introducing exogenous genetic elements into a target cell genome often result in unwanted integration, which can disrupt the host cell's genetic stability and functionality.
Innovation Solution
A system utilizing a recombinase polypeptide, specifically a serine recombinase, integrated with a retroviral vector that is integration-deficient, to introduce exogenous genetic elements into a target cell genome, allowing precise modification without integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a retroviral vector is used to introduce exogenous genetic elements into a target cell genome, then the efficiency of genetic element introduction is improved, but unwanted integration occurs which disrupts genetic stability
Solution Approach 1:
The integrase enzyme is removed from the retroviral vector system, extracting the problematic integration function while preserving the reverse transcription and packaging capabilities. This allows the vector to deliver genetic material without causing unwanted genomic integration, thus maintaining genetic stability while retaining delivery efficiency.
Solution Approach 2:
The retroviral vector system is segmented into separate functional components: the integration-deficient vector handles delivery and reverse transcription, while integrase is provided separately as a trans-complementing protein. This segmentation allows controlled integration only when both components are present, preventing unwanted autonomous integration.
2Stability of the object's composition
If integration activity is enabled in a retroviral vector, then exogenous genetic elements can be stably incorporated into the genome, but unwanted integration events occur that disrupt host cell functionality
Solution Approach 1:
An intermediary mechanism is introduced where integrase acts as a controlled mediator rather than an autonomous enzyme. The integrase is provided separately and only functions when both the integration-deficient vector and integrase protein are present in the same cell, enabling stable incorporation only under controlled conditions and preventing unwanted autonomous integration events.
3Productivity
If a standard retroviral integrase is used, then integration of exogenous DNA occurs efficiently, but precision and control over integration location is reduced
Solution Approach 1:
The system implements local quality control by using integrase with altered activity that requires specific conditions for function. The integrase is engineered to have reduced autonomous activity but can still perform integration when trans-complemented, creating a localized and controlled integration event rather than random widespread integration.
Data Source
AI summary
Among other things, provided herein are systems that replace the natural random integration activity of a retrovirus with site-specific integration machinery. This approach allows for a more precise targeting of a gene of interest into a human genome, e.g., for therapeutic purposes. The system may include integration-deficient retrovirus (e.g., lentivirus) (IDLV), in which the natural integration activity has been reduced (e.g., by mutation to the viral integrase polypeptide). Instead, the system may comprise a site-specific recombinase (e.g., a serine recombinase, e.g., a serine integrase) capable of directing insertion of a template DNA, or portion thereof, into a desired site in the human genome.