Generating Recombinant Avian Herpesvirus Vectors with CRISPR/Cas9 Gene Editing
January 7th, 2019
16.5K views
Herpesvirus of turkeys (HVT) is widely used as a vector platform for the generation of recombinant vaccines against a number of avian diseases. This article describes a simple and rapid approach for the generation of recombinant HVT-vectored vaccines using an integrated NHEJ-CRISPR/Cas9 and Cre-Lox system.
Overview
This article presents a rapid method for generating recombinant vaccines using Herpesvirus of turkeys (HVT) as a vector. The approach integrates NHEJ-CRISPR/Cas9 and Cre-Lox systems for efficient antigen introduction.
Key Study Components
Area of Science
- Virology
- Immunology
- Genetic Engineering
Background
- HVT is a widely used vector for avian vaccines.
- Recombinant vaccines can enhance protection against avian diseases.
- The integration of CRISPR/Cas9 technology allows for precise modifications.
- The Cre-Lox system facilitates the removal of unnecessary components post-insertion.
Purpose of Study
- To develop a streamlined method for creating recombinant HVT-vectored vaccines.
- To demonstrate the efficiency of the integrated NHEJ-CRISPR/Cas9 and Cre-Lox system.
- To enable the introduction of multiple viral genes for multivalent vaccine development.
Methods Used
- Transfection of chick embryo fibroblasts with Cas9 guide RNA and donor plasmids.
- Infection of transfected cells with HVT virus.
- Cell sorting based on GFP expression to isolate successful recombinant cells.
- PCR and gel electrophoresis for verification of recombinant viruses.
Main Results
- Successful introduction of viral antigens into the HVT genome.
- Isolation of GFP-positive cells indicating successful transfection.
- Generation of recombinant HVT viruses verified through PCR.
- Demonstration of the ability to create multivalent vaccines.
Conclusions
- The integrated approach is efficient for recombinant vaccine development.
- GFP visualization aids in the selection of successful clones.
- This method can be adapted for various avian herpes viruses.
Frequently Asked Questions
What is the significance of using HVT as a vector?
HVT is effective for delivering recombinant vaccines against avian diseases, enhancing immune responses.
How does the Cre-Lox system work in this context?
The Cre-Lox system allows for the removal of the GFP marker after successful insertion of the viral antigen.
What are the advantages of using CRISPR/Cas9 technology?
CRISPR/Cas9 provides precise editing capabilities, allowing for targeted modifications in the viral genome.
Can this method be used for other viruses?
Yes, the approach can be adapted for other avian herpes viruses to develop multivalent vaccines.
What role do chick embryo fibroblasts play in this study?
Chick embryo fibroblasts serve as the host cells for transfection and viral infection, facilitating vaccine development.
How are successful recombinant viruses verified?
Verification is done through PCR amplification and gel electrophoresis to confirm the presence of the inserted genes.
Executive Industry Relevance
CRISPR/Cas9-mediated genome editing of Herpesvirus of turkeys (HVT) enables rapid generation of recombinant avian vaccine vectors, supporting scalable multivalent vaccine development. This approach streamlines antigen insertion and marker removal, enhancing predictive confidence in vector engineering and accelerating early discovery to preclinical transitions. The method's efficiency and adaptability position it as a reusable platform for avian vaccine R&D portfolios.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables precise insertion of antigen expression cassettes for functional validation of vaccine targets.
- Supports biological de-risking by confirming antigen expression and genomic integration in the vector.
- Facilitates rapid hypothesis testing for new vaccine constructs and multivalent strategies.
Screening & Assay Development
- Provides visual selection of recombinant clones via GFP marker for efficient screening workflows.
- Standardizes verification of genomic edits using PCR and immunofluorescence assays.
- Delivers reproducible, quantitative outputs for downstream assay development and optimization.
Translational & Preclinical Research
- Enables continuity from vector engineering to preclinical immunogenicity assessment in avian models.
- Aligns with translational biomarker strategies by confirming antigen expression at the protein level.
- Supports risk-adjusted advancement of vaccine candidates based on molecular and phenotypic validation.
Pipeline & Workflow Integration
This genome editing workflow integrates from early discovery through lead identification and preclinical validation in avian vaccine development pipelines.
- Discovery Biology: Supports hypothesis-driven insertion and validation of vaccine antigens in HVT vectors.
- Screening: Enables high-throughput selection and confirmation of recombinant clones using fluorescence and PCR.
- Analytics: Provides quantitative PCR and immunofluorescence readouts for robust comparison of candidate constructs.
- Translational Research: Bridges molecular engineering with functional protein expression and preclinical readiness.
- Enterprise Reuse: Establishes a modular, adaptable platform for future recombinant vaccine vector projects.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence in antigen expression and vector stability.
- Operational Value: Streamlines marker selection and removal, reducing hands-on time and variability.
- Strategic Value: Accelerates go/no-go decisions for candidate advancement and portfolio triage.
- Portfolio Impact: Enables scalable, risk-adjusted development of multivalent vaccine vectors.
Implementation Considerations
- Requires expertise in CRISPR/Cas9 design, cell culture, and virology workflows.
- Demands access to cell sorting, PCR, and fluorescence microscopy infrastructure.
- Necessitates standardized protocols for reproducibility across teams and projects.
- Adaptation to other avian herpesvirus vectors may require locus-specific optimization.
- High transfection efficiency is critical for successful genome editing and downstream selection.
Biopharma FAQs
Why is null hypothesis testing critical for VP2 antigen insertion?
Null hypothesis testing ensures that observed VP2 expression and genomic integration are due to targeted CRISPR/Cas9 editing, not background events, supporting robust target validation in vaccine vector development.
How does independent variable isolation improve GFP marker excision analysis?
Isolating the Cre-Lox excision step allows teams to attribute loss of GFP fluorescence specifically to Cre-mediated recombination, clarifying workflow efficiency and supporting pipeline decision points.
What do quantitative PCR and immunofluorescence measurements enable in this workflow?
Quantitative PCR and immunofluorescence provide objective confirmation of antigen insertion and protein expression, enabling reliable comparison of recombinant clones and supporting data-driven candidate selection.
Why are replication requirements important for cross-team recombinant virus validation?
Replication across multiple passages and independent clones ensures reproducibility of antigen expression and genomic stability, facilitating cross-functional collaboration and enterprise-level confidence in vector performance.
What statistical analysis capabilities are needed before advancing recombinant HVT candidates?
Teams require statistical analysis of PCR and immunofluorescence data to confirm integration efficiency, expression consistency, and to set advancement thresholds for candidate selection in the vaccine development pipeline.
Chapters in this video
0:04
Title
0:53
CRISPR/Cas9-mediated Knock-in: Transfection and Infection
2:14
Harvesting and Purification of the HVT Recombinant Virus
5:38
Excision of the Fluorescent Reporter Gene via the Cre-lox System
6:23
Plaque Purification
7:31
Verification of the Recombinant HVT
9:31
Stability of the Recombinant Virus
10:36
Results: Analysis of the Generated Recombinant Avian Herpesvirus Vectors
11:38
Conclusion
