Continuous Directed Evolution in Metazoan Cells
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Solution Overview
Problem
Current directed evolution platforms are limited by slow growth rates of eukaryotic cells and the need for discrete steps in mutagenesis, screening, and amplification, which restrict the size of libraries that can be effectively screened and amplified, especially in metazoan cells.
Innovation Solution
The development of a continuous directed evolution method using engineered, non-naturally occurring DNA viruses and metazoan cells with modified genomes, where the DNA viruses have a deleted viral polymerase and a protein necessary for production, and the cells express an error-prone DNA virus polymerase, enabling rapid replication and selection of infectious particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If directed evolution is performed in metazoan cells using traditional methods, then the biological relevance is improved, but the time required for each evolution round increases significantly
Solution Approach 1:
The system divides the directed evolution process into two independent components: (1) viral replication and gene amplification occurs continuously and rapidly, while (2) selection pressure is applied through engineered cellular mechanisms. This segmentation allows the time-consuming cellular selection step to be decoupled from the rapid viral replication step, enabling continuous evolution without waiting for slow cellular division cycles.
Solution Approach 2:
The system pre-establishes an error-prone DNA polymerase expression system in the metazoan cells before viral infection. This preliminary action ensures that when the virus infects the cell, mutagenesis is immediately active during viral DNA replication, eliminating the need for separate mutagenesis steps and accelerating the evolution process while maintaining biological relevance.
2Ease of manufacture
If discrete steps are used for mutagenesis, screening, and amplification, then the process control is improved, but the productivity decreases
Solution Approach 1:
The system implements continuous viral replication and gene amplification within the metazoan cells, eliminating the need for repeated discrete steps of harvest, transfection, and amplification. The virus continuously replicates and produces mutant variants throughout the cell culture period, maintaining continuous evolutionary pressure and significantly increasing the number of evolution rounds that can be achieved in a given time frame while preserving process control through engineered selection mechanisms.
3Productivity
If the viral polymerase is present, then the virus replication efficiency is improved, but the mutagenesis capability is reduced
Solution Approach 1:
The system introduces an intermediary error-prone DNA polymerase that is expressed by the metazoan cell and acts as a mediator during viral DNA replication. This intermediary polymerase introduces mutations at high rates while the virus's own replication machinery maintains efficient replication. The intermediary polymerase thus bridges the need for both high replication efficiency and high mutagenesis rates, allowing the virus to replicate rapidly while accumulating genetic diversity.
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 allows for rapid and continuous directed evolution in metazoan cells, enabling larger library sizes and faster evolution cycles, reducing the risk of 'cheating' mechanisms and improving the scalability and efficiency of biomolecule development.
Implementation Method 1
The generation of infectious viruses that can infect new cells depends on the evolution of a gene of interest which is driven by an error-prone DNA virus DNA polymerase
Data Source
AI summary
Disclosed herein are methods of performing continuous directed evolution in complex biological systems, including metazoan cells. These methods include the infection of engineered, non-naturally occurring metazoan cells with engineered, non-naturally occurring DNA viruses. The generation of infectious viruses that can infect new cells depends on the evolution of a gene of interest which is driven by an error-prone adenoviral polymerase. Also disclosed herein, are the compositions of engineered, non-naturally occurring metazoan cells and engineered, non-naturally occurring DNA viruses that function as components in the continuous directed evolution methodologies.