Poxvirus K3 Host Range Selection for Recombinant Virus Generation
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Solution Overview
Problem
Current methods for generating recombinant poxviruses, such as vaccinia virus, are time-consuming and limited by the need for non-poxvirus derived selection markers, which restricts their application in human vaccines and therapeutics due to the requirement for specific host cell compatibility and inefficient selection processes.
Innovation Solution
A method utilizing host range selection by poxvirus K3 proteins, where a parent poxvirus with disrupted E3 and K3 genes is used in conjunction with an insertion cassette containing K3 orthologs to facilitate crossover events and generate recombinant viruses that can replicate in specific host cells, allowing for targeted expression and selection of recombinant poxviruses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chemical selection methods (bromo-deoxyuridine, antibiotics) or color marker based selection (β-gal, GFP) are used to select recombinant vaccinia viruses, then selection efficiency is improved, but the process becomes time-consuming and requires non-poxvirus derived genes as selection markers
Solution Approach 1:
The invention extracts and utilizes the native poxvirus K3 gene as a selection marker, removing the dependency on non-poxvirus derived selection markers. The K3 gene is naturally present in poxvirus genomes and its expression confers host range expansion, allowing selection of recombinant viruses without requiring external chemical or color-based markers from other virus families.
Solution Approach 2:
The poxvirus K3 gene serves as a self-contained selection marker that is intrinsic to the poxvirus system. The K3 gene product naturally antagonizes PKR-mediated antiviral responses, enabling the virus to replicate in a broader host range without requiring external selection agents. This self-service mechanism eliminates the need for time-consuming chemical selection processes.
2Ease of manufacture
If non-poxvirus derived selection markers are used, then recombinant virus selection is achieved, but application in human vaccines and therapeutics is restricted due to host cell compatibility requirements
Solution Approach 1:
The K3 gene serves multiple functions: it acts as both a virulence factor that antagonizes host PKR-mediated antiviral responses and as a selection marker that confers host range expansion. This multi-functionality allows the same gene to enable both virus replication and selection, eliminating the need for separate selection markers and improving adaptability to different host cells for vaccine and therapeutic applications.
Solution Approach 2:
The invention changes the host range parameter of the poxvirus by introducing or modifying the K3 gene. The K3 gene product alters the virus's ability to replicate in different host cells by antagonizing PKR-mediated antiviral responses, thereby expanding host compatibility. This parameter change enables broader application in human vaccines and therapeutics without requiring host-specific adaptation.
3Ease of manufacture
If homologous recombination is used to generate recombinant vaccinia viruses, then the desired recombinant viruses can be produced, but they represent only a small percentage of the total virus population requiring complex selection
Solution Approach 1:
The K3 gene acts as an intermediary that mediates both the recombination process and the selection of recombinant viruses. By linking the K3 gene expression to the recombinant virus construction (either through co-expression or as part of the recombination event), the K3 gene serves as a mediator that enables easy identification and enrichment of recombinant viruses from the total virus population.
Data Source
AI summary
Described herein is a novel method for generation of recombinant poxviruses using an E3 and K3 double deletion mutant virus as the parental virus for generation of recombinant viruses. Following allowing for crossing over between the parental virus and an insertion cassette including an orthopox K3 peptide and the gene of interest, recombinant viruses are selected by infecting a host cell line permissive for the orthopox K3 peptide but not for the E3 and K3 double mutant parental virus. It is also demonstrated that a specific small molecule inhibitor of NEDD8 activating enzyme, MLN4924, can completely block poxvirus K3 family protein mediated PKR degradation and virus replication.