Stable SARS-CoV-2 RNA Cell Clones for Persistent Replication

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Solution Overview

Problem

Current systems for SARS-CoV-2 replication and translation do not allow for persistent replication in cell lines due to intrinsic toxicity, making them impractical for high-throughput screening of antiviral compounds.

Innovation Solution

Development of stable cell clones harboring non-native coronavirus genomes with genetically inactivated spike, envelope, and membrane genes, and optionally nucleocapsid genes, along with reporter and marker genes, and specific Nsp1 gene substitutions, enabling autonomous replication and high-throughput screening in a biosafety level 2 setting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If transient replicon systems are used for SARS-CoV-2, then viral gene expression can be achieved, but persistent replication in cell lines is prevented due to intrinsic toxicity

Engineering Contradiction:

Improvepersistent replication capabilityVSAvoidintrinsic toxicity

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and removes the toxic components (functional S, E, and M genes) from the SARS-CoV-2 replicon system, retaining only the essential replication machinery (non-structural proteins) needed for persistent replication without the harmful effects of viral structural protein expression

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces specific mutations in the Nsp1 gene (K164A and H165A substitutions) that alter the protein's properties to reduce cellular toxicity while maintaining replication competence, enabling stable cell line establishment

Inventive Principle:

Principle #35Parameter changes

2Productivity

If transient replicon systems are used, then viral gene expression is possible, but rapid loss of viral sgmRNA or reporter gene occurs making HTS impractical

Engineering Contradiction:

Improvehigh-throughput screening capabilityVSAvoidviral sgmRNA persistence

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent removes the cause of rapid sgmRNA loss by eliminating functional S, E, and M genes, allowing the replicon system to maintain stable sgmRNA levels and reporter gene expression over extended periods suitable for HTS applications

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent establishes continuous, stable viral RNA replication and reporter gene expression in cell lines that can be maintained indefinitely, enabling continuous high-throughput screening operations without the rapid decay seen in transient systems

Inventive Principle:

Principle #20Continuity of useful action

3Reliability

If transient replicon systems are used, then viral replication can be studied, but inability to generate master and working cell banks prevents lot consistency

Engineering Contradiction:

Improvelot consistencyVSAvoidcell bank generation

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent creates cell lines that autonomously maintain the replicon system through stable integration and persistent replication, allowing the cells to serve themselves by continuously producing viral RNA and reporter proteins without requiring repeated transfection or external maintenance

Inventive Principle:

Principle #25Self-service

4Productivity

If transient replicon systems are used, then viral gene expression is achieved, but scaling up for industrial processes becomes challenging

Engineering Contradiction:

Improveindustrial scale capabilityVSAvoidsystem robustness

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent removes the problematic functional viral genes that complicate scaling, creating a simplified replicon system that can be robustly manufactured and scaled for industrial antiviral screening processes

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces Nsp1 mutations that stabilize the replicon system, making it more robust and easier to scale up for industrial applications while maintaining the essential replication function

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250250647A1Stable cell clones harboring replicating SARS-COV-2 RNA

Publication Date: 2025.08.07 THE GOVERNMENT OF THE UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY DEPARTMENT OF HEALTH & HUMAN SERVICES

AI summary

Coronavirus genomes comprising non-native SARS-CoV-2 RNAs having genetically inactivated spike (S), envelope (E), and membrane (M) genes, and optionally a genetically inactivated nucleocapsid (NP) gene, are provided. Such coronavirus genomes further include a reporter gene and a marker gene, and substitutions within a non-structural protein 1 (Nsp1) gene (such as K164A and H165A). Also provided are cells containing the coronavirus genomes, for example, stable cell clones having the isolated non-native coronavirus genome autonomously replicating inside the cells. Also provided are methods of using such cells, for example, methods of identifying anti-viral compounds, such as quantitative high-throughput screening methods that can optionally be performed in a biosafety level 2 (BSL2) laboratory.