Rescue of Recombinant Zika Virus from a Bacterial Artificial Chromosome cDNA Clone
June 24th, 2019
The recent epidemic of Zika virus highlights the importance of establishing reverse genetic approaches to develop vaccines and/or therapeutic strategies. Here, we describe the protocol to rescue an infectious recombinant Zika virus from a full-length cDNA clone assembled in a bacterial artificial chromosome under the control of the human cytomegalovirus immediate-early promoter.
Overview
This study presents a protocol for generating infectious recombinant Zika virus from a full-length cDNA clone. The method utilizes a bacterial artificial chromosome (BAC) system controlled by the human cytomegalovirus promoter, enabling the manipulation of the viral genome for research and vaccine development.
Key Study Components
Area of Science
- Virology
- Genetic Engineering
- Vaccine Development
Background
- The Zika virus epidemic underscores the need for effective vaccines.
- Reverse genetics allows for direct manipulation of viral genomes.
- Constructing infectious clones can mitigate toxicity issues associated with viral genomes.
- This methodology can be applied to other flaviviruses and positive-stranded RNA viruses.
Purpose of Study
- To develop a reverse genetic system for Zika virus.
- To facilitate the study of viral biology and pathogenesis.
- To create a platform for vaccine strategy development.
Methods Used
- Construction of a Zika virus cDNA clone using BAC technology.
- Transfection of Vero cells with the BAC cDNA clone.
- Purification of BAC using alkaline lysis.
- Assessment of viral titer and cytopathic effects post-transfection.
Main Results
- Infectious Zika virus was successfully rescued with high titers.
- The rescued virus induced a clear cytopathic effect in Vero cells.
- Immunofluorescence confirmed the identity of the rescued virus.
- Stable cDNA clones were generated for further research.
Conclusions
- This study demonstrates a reliable method for generating infectious Zika virus.
- The BAC system is effective for manipulating the viral genome.
- Results can aid in the development of vaccines and therapeutic strategies.
Frequently Asked Questions
Executive Industry Relevance
This protocol enables the generation of stable infectious clones for flaviviruses like Zika virus, addressing a critical bottleneck in antiviral and vaccine development. By overcoming genome toxicity in bacterial systems, it supports reliable target validation and mechanistic de-risking in early discovery. The approach provides a reusable platform for studying viral pathogenesis and evaluating therapeutic candidates.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables direct manipulation of the viral genome to interrogate therapeutic hypotheses and validate targets.
- Operational Value: Provides a stable, reproducible system for functional target validation without bacterial toxicity artifacts.
Screening & Assay Development
- Scientific Value: Generates quantifiable viral outputs such as titer and cytopathic effect for compound screening.
- Operational Value: Produces homogeneous plaques and consistent viral titers, supporting assay standardization and reproducibility.
Translational & Preclinical Research
- Scientific Value: Supports disease-relevant studies of viral pathogenesis and immune response in Vero cells.
- Operational Value: Enables continuous propagation and stock production for preclinical efficacy and safety testing.
Pipeline & Workflow Integration
The method fits within the discovery continuum from target validation through lead identification to preclinical evaluation, providing a scalable source of infectious virus for downstream applications.
- Discovery Biology: Facilitates hypothesis testing and pathway clarification via genome editing of the infectious clone.
- Screening: Delivers standardized virus stocks for high-throughput antiviral compound evaluation.
- Analytics: Enables quantitative readouts including plaque-forming units and immunofluorescence-based validation.
- Translational Research: Bridges discovery to preclinical work by producing authentic virus for efficacy models.
- Enterprise Reuse: Establishes a platform technology applicable to other flaviviruses and positive-strand RNA viruses with unstable genomes.
Operational & Enterprise Impact
- Scientific Value: Enhances predictive confidence by reducing mechanistic ambiguity in viral pathogenesis studies.
- Operational Value: Ensures batch-to-batch consistency and scalability of virus production for screening campaigns.
- Strategic Value: Improves go/no-go decisions by enabling early assessment of antiviral efficacy and resistance profiles.
- Portfolio Impact: Supports risk-adjusted prioritization of candidates through reliable preclinical data generation.
Implementation Considerations
- Molecular cloning expertise for fragment assembly and BAC construction.
- Access to transfection reagents and equipment for eukaryotic cell delivery.
- Biosafety Level 2 infrastructure for handling infectious virus.
- Standardized cell culture systems for consistent virus rescue and titration.
- Sequence verification steps to confirm clone integrity post-purification.
Biopharma FAQs
Chapters in this video
0:04
Title
1:09
Construction of a ZIKV Infectious cDNA Clone in a BAC
1:41
Preparation of High-purity pBAC-ZIKV for the Rescue of Infectious rZIKV
2:36
Rescue of Infectious rZIKV from the BAC cDNA Clone by Transfection of Vero Cells
4:40
Amplification and Generation of Viral Stocks
5:58
Results: Analysis of the Rescued Recombinant Zika Virus
7:34
Conclusion
