Confocal Imaging of Double-Stranded RNA and Pattern Recognition Receptors in Negative-Sense RNA Virus Infection
January 26th, 2019
Double-stranded RNA produced during RNA virus replication can be recognized by pattern recognition receptors to induce an innate immune response. For negative-sense RNA viruses, the interaction between the low-level dsRNA and PRRs remains unclear. We have developed a confocal microscopy method to visualize arenavirus dsRNA and PRR in individual cells.
Traditional double-strand RNA detection assay usually is not sensitive enough to detect double-strand RNA formed in negative-sense RNA virus infection.Therefore the interaction between double-stranded RNA and host pattern recognition receptors has remained largely elusive for these viruses.Utilizing this protocol we are able to visualize and characterize the interaction between viral nuclear protein, double-strand RNA and host a PRRs at a single-cell level for negative-sense RNA virus.This is a multiplex assay that allows for simultaneous staining of double-stranded RNA and two viral or host protein targets in individual cells.Unlike the RNA-FISH assay this technique is RNA sequence independent and usually compatible with antibody detection of protein targets.Begin 24 hours prior to infection by seeding 200, 000 human lung epithelial A549 cells onto Poly-D-Lysine coated glass cover slips in 12-well plates and growing them at 37
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Overview
This study investigates the recognition of double-stranded RNA (dsRNA) produced during RNA virus replication by pattern recognition receptors (PRRs) to induce an innate immune response. The focus is on negative-sense RNA viruses, where the interaction between low-level dsRNA and PRRs is not well understood. A confocal microscopy method has been developed to visualize arenavirus dsRNA and PRRs in individual cells.
Key Study Components
Area of Science
- Neuroscience
- Immunology
- Virology
Background
- Double-stranded RNA is a byproduct of RNA virus replication.
- Pattern recognition receptors play a crucial role in the innate immune response.
- The interaction between dsRNA and PRRs in negative-sense RNA viruses is poorly understood.
- Visualizing dsRNA and PRRs can enhance understanding of viral immune evasion.
Purpose of Study
- To elucidate the interaction between dsRNA and PRRs in negative-sense RNA viruses.
- To develop a method for visualizing these interactions in individual cells.
- To contribute to the understanding of the innate immune response to RNA viruses.
Methods Used
- Confocal microscopy for visualization of dsRNA and PRRs.
- Cellular assays to assess the immune response.
- Analysis of dsRNA levels during viral replication.
- Comparative studies with different RNA viruses.
Main Results
- Successful visualization of arenavirus dsRNA and PRRs in individual cells.
- Identification of specific interactions between dsRNA and PRRs.
- Insights into the immune response mechanisms triggered by dsRNA.
- Clarification of the role of dsRNA in viral pathogenesis.
Conclusions
- The developed confocal microscopy method is effective for studying dsRNA and PRR interactions.
- Understanding these interactions may lead to new therapeutic strategies against RNA viruses.
- This research contributes to the broader field of viral immunology.
Frequently Asked Questions
Executive Industry Relevance
Visualizing low-abundance double-stranded RNA (dsRNA) in negative-sense RNA virus infection addresses a critical gap in understanding innate immune activation and viral immune evasion. This capability supports target validation and mechanistic de-risking in antiviral discovery by enabling direct observation of pattern recognition receptor (PRR) engagement with viral replicative intermediates. The method enhances predictive confidence in early-stage target selection for arenavirus and related pathogens, informing portfolio prioritization in high-containment pathogen programs.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables interrogation of therapeutic hypotheses by visualizing dsRNA-PRR interactions at single-cell resolution in pathogenic virus models.
- Operational Value: Provides a sensitive, sequence-independent detection method compatible with multiplexed protein staining for pathway clarification.
- Predictive Value: Supports biological de-risking of PRR targets by confirming ligand engagement in relevant infection contexts.
Screening & Assay Development
- Assay Readiness: Generates quantitative, spatially resolved readouts of dsRNA and PRR colocalization for assay standardization.
- Screening Relevance: Prepares validated biological systems for downstream compound screening by establishing baseline immune activation metrics.
- Platform Utility: Compatible with antibody-based detection, enabling reuse across viral targets and host proteins in imaging workflows.
Translational & Preclinical Research
- Translational Continuity: Bridges discovery observations to preclinical validation by mapping dsRNA distribution and PRR recruitment in disease-relevant systems.
- Mechanistic Insight: Clarifies spatial and temporal dynamics of innate immune signaling, informing biomarker selection for pathway modulation.
- Risk-Adjusted Advancement: Enables data-driven go/no-go decisions based on visual confirmation of target engagement in high-pathogenicity models.
Pipeline & Workflow Integration
The method fits within the discovery continuum from target hypothesis testing through lead identification to preclinical validation, particularly for immunomodulatory antivirals targeting PRR pathways.
- Discovery Biology: Supports hypothesis testing of PRR agonist/antagonist mechanisms by visualizing dsRNA as the endogenous ligand in infected cells.
- Screening: Delivers reproducible, quantitative imaging outputs that enable comparison of compound effects on dsRNA-PRR interactions.
- Analytics: Provides multiplexed fluorescence readouts (dsRNA, viral protein, PRR) for high-content analysis of immune activation states.
- Translational Research: Connects in vitro observations to preclinical continuity by confirming PRR activation in primary or stem-cell-derived lung epithelial models.
- Enterprise Reuse: Establishes a standardized imaging platform applicable to multiple negative-sense RNA viruses and host targets beyond arenaviruses.
Operational & Enterprise Impact
- Scientific Value: Increases target validation confidence by reducing mechanistic ambiguity in PRR-ligand interactions.
- Operational Value: Enhances assay reproducibility and scalability through standardized confocal protocols and sensitive dsRNA detection.
- Strategic Value: Improves go/no-go decision quality by providing direct visual evidence of pathway modulation, reducing late-stage attrition.
- Portfolio Impact: Enables risk-adjusted prioritization of immunomodulatory candidates based on confirmed target engagement in pathogenic virus contexts.
Implementation Considerations
- Requires expertise in confocal microscopy, immunofluorescence staining, and biosafety-level-appropriate virology techniques.
- Dependent on access to high-sensitivity dsRNA antibodies (e.g., 9D5 clone) and compatible fluorescence imaging infrastructure.
- Necessitates standardization across laboratories for consistent dsRNA signal quantification and colocalization analysis.
- Must account for cell model variability (e.g., A549 vs. primary airway epithelium) in dsRNA production and PRR expression levels.
- Practical limitations include potential antibody cross-reactivity and the need for optimization in high-containment (BSL-3/BSL-4) settings.
Biopharma FAQs
Chapters in this video
0:04
Title
1:05
Preparation of A549 Cells and JUNV (Junn virus) Infection
2:09
Fixation and Immunostaining
5:10
Results: Distribution and Colocalization Between the Retinoic Acid Like Receptors RLRs (RIG-I and MDA-5) and dsRNA in JUNV-infected Cells
5:52
Conclusion
