Using Bioluminescent Imaging to Investigate Synergism Between Streptococcus pneumoniae and Influenza A Virus in Infant Mice
April 14th, 2011
17.2K views
A concurrent infection with influenza A virus is one of the factors implicated in the induction of invasive pneumococcal disease during asymptomatic Streptococcus pneumoniae carriage. Here we describe a mixed infection method using infant mice to investigate the synergism between these two respiratory pathogens.
Overview
This study investigates the synergistic effects of concurrent influenza A virus infection on the progression of invasive pneumococcal disease during asymptomatic carriage of Streptococcus pneumoniae in infant mice. The research utilizes a mixed infection model to monitor the interactions between these two respiratory pathogens.
Key Study Components
Area of Science
- Infectious diseases
- Microbiology
- Immunology
Background
- Influenza A virus can exacerbate pneumococcal disease.
- Asymptomatic carriage of S. pneumoniae is common in infants.
- Understanding pathogen interactions is crucial for developing treatment strategies.
- Mixed infection models provide insights into disease mechanisms.
Purpose of Study
- To assess the impact of influenza A on S. pneumoniae dissemination.
- To evaluate the advantages of in vivo bioluminescent imaging in tracking infections.
- To explore the kinetics of infection in various organs.
Methods Used
- Preparation of infectious stalks from S. pneumoniae and influenza A virus.
- Intranasal infection of infant mice with S. pneumoniae followed by influenza A.
- In vivo bioluminescent imaging to monitor infection progression.
- Use of anesthetics for imaging procedures.
Main Results
- Bioluminescent imaging revealed enhanced dissemination of S. pneumoniae in co-infected mice.
- Infection kinetics were successfully tracked over time in the same animal.
- The method allowed for monitoring of infections in less accessible sites.
- Results indicate a significant interaction between the two pathogens.
Conclusions
- The mixed infection model is effective for studying pathogen interactions.
- In vivo imaging techniques provide valuable insights into disease progression.
- Findings could inform future therapeutic approaches for co-infections.
Frequently Asked Questions
What is the significance of studying co-infections?
Studying co-infections helps understand how different pathogens interact and affect disease severity.
How does bioluminescent imaging work?
Bioluminescent imaging allows researchers to visualize and track the spread of bioluminescent bacteria in live animals.
What are the advantages of using infant mice in this study?
Infant mice are more susceptible to respiratory infections, making them ideal for studying early-life infections.
Why is it important to monitor infection kinetics?
Monitoring infection kinetics provides insights into how infections progress and can inform treatment strategies.
What role does influenza A play in pneumococcal disease?
Influenza A can exacerbate pneumococcal disease by compromising the immune response and facilitating bacterial spread.
What methods were used to prepare the infectious agents?
Infectious stalks were prepared using standard broth cultures for S. pneumoniae and embryonated chicken eggs for influenza A.
Executive Industry Relevance
Understanding pathogen synergy between influenza and Streptococcus pneumoniae informs target validation for anti-infective strategies. Bioluminescent imaging enables longitudinal tracking of bacterial dissemination in vivo, supporting mechanistic de-risking in preclinical models. This approach enhances predictive confidence in evaluating therapeutic interventions for respiratory co-infections.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Interrogates therapeutic hypotheses by quantifying synergistic pathogen interactions in a disease-relevant system.
- Operational Value: Enables functional target validation through real-time monitoring of bacterial load dynamics.
- Predictive Value: Supports lead identification by measuring exacerbation of pneumococcal dissemination under viral co-infection.
Screening & Assay Development
- Scientific Value: Prepares validated biological systems for downstream antiviral or antibacterial compound screening.
- Operational Value: Provides standardized, quantitative bioluminescent readouts for assay reproducibility.
- Scalability: Supports platform reuse across multiple time points in the same animal, reducing cohort size.
Translational & Preclinical Research
- Scientific Value: Models disease-relevant system to study translational biomarker alignment between viral and bacterial load.
- Operational Value: Enables continuity from discovery through preclinical validation via non-invasive longitudinal imaging.
- Risk Mitigation: Informs risk-adjusted advancement decisions by revealing kinetic thresholds of synergistic exacerbation.
Pipeline & Workflow Integration
The method integrates into early discovery workflows by enabling hypothesis testing of host-pathogen interactions prior to lead optimization.
- Discovery Biology: Supports pathway clarification by visualizing temporal and spatial dissemination of S. pneumoniae in co-infected hosts.
- Screening: Delivers assay readiness through standardized bioluminescent signal quantification in nasopharyngeal and pulmonary compartments.
- Analytics: Generates quantitative measurements of bacterial luminescence intensity to compare mono- and co-infection conditions.
- Translational Research: Connects to preclinical continuity by modeling infant mouse susceptibility to respiratory co-infections.
- Enterprise Reuse: Establishes a reusable imaging platform for evaluating anti-infective candidates against synergistic pathogen pairs.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence by reducing mechanistic ambiguity in pathogen synergy mechanisms.
- Operational Value: Enhances reproducibility and standardization through serial in vivo imaging of individual animals.
- Strategic Value: Improves go/no-go decisions by identifying early biomarkers of exacerbated bacterial dissemination.
- Portfolio Impact: Enables risk-adjusted prioritization of compounds targeting viral-bacterial interaction nodes.
Implementation Considerations
- Requires expertise in infant mouse handling, invasive pathogen work, and bioluminescent imaging instrumentation.
- Dependent on access to IVIS imaging systems and anaerobic culture capabilities for S. pneumoniae stock preparation.
- Necessitates cross-team standardization of anesthesia protocols and imaging time points for longitudinal consistency.
- Involves adaptation considerations when extending the model to adult mice or alternative bacterial strains.
- Limited by the need for biosafety level 2 facilities and ethical approvals for neonatal animal infection studies.
Biopharma FAQs
Why does bioluminescent imaging matter for target validation in co-infection models?
Bioluminescent imaging enables real-time, quantitative tracking of bacterial dissemination in live animals, providing direct readouts of pathogen load without terminal sampling. This supports target validation by allowing researchers to measure the impact of therapeutic interventions on synergistic exacerbation over time. The method reduces variability between animals, increasing confidence in target engagement data.
How does isolation of influenza virus as an independent variable support discovery pipeline objectives?
Isolating influenza virus exposure allows researchers to assess its specific effect on S. pneumoniae progression in colonized infant mice, establishing causality in synergistic interactions. This independent variable manipulation supports hypothesis testing in early discovery by distinguishing viral facilitation from bacterial intrinsic virulence. The approach enables de-risking of targets by confirming that observed exacerbation is virus-dependent.
What quantitative dependent variable measurements enable assessment of synergistic pathogenesis?
Bioluminescent signal intensity from the nasopharyngeal and lung regions serves as a quantitative dependent variable reflecting S. pneumoniae burden. Changes in signal intensity over time indicate bacterial dissemination kinetics, allowing comparison between mono- and co-infected conditions. These measurements provide objective data to evaluate the magnitude of viral exacerbation on bacterial load.
Why do replication requirements matter for cross-functional collaboration in infectious disease research?
Replication across multiple animals and time points ensures that observed synergistic effects are consistent and not due to individual variability, which is critical for assay transfer between biology and pharmacology teams. Standardized imaging protocols and blinded analysis enhance reproducibility, enabling reliable data sharing across discovery and preclinical functions. This consistency supports confident advancement decisions in therapeutic development pipelines.
What statistical analysis capabilities are required before implementing this imaging approach in drug discovery workflows?
Implementation requires capability to perform longitudinal data analysis, including repeated measures ANOVA or mixed-effects models to account for within-animal correlation over time. Threshold-based analysis of bioluminescent signal increase (e.g., fold-change relative to baseline) must be supported to define significant exacerbation. Access to software for image quantification (e.g., Living Image) and statistical packages (e.g., GraphPad, R) is necessary for robust interpretation.
Chapters in this video
0:05
Title
1:47
Preparation of Infectious Stock of Bioluminescent S. pneumoniae
3:14
Growth and Preparation of Influenza A Virus Stocks
6:22
Intranasal Infection of Mice with Bioluminescent S pneumoniae and/or Influenza A Virus
9:15
In vivo Bioluminescent Imaging of Co-Infection of Respiratory Tract with S. pneumoniae and Influenza Virus
10:21
Conclusion
7:25
Bioluminescent Imaging Using the IVIS Spectrum (Caliper Sciences)
