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Updated: Jun 10, 2025
Longitudinal Follow-Up of Urinary Tract Infections and Their Treatment in Mice using Bioluminescence Imaging
Published on: June 14, 2021
Development of bioluminescent Group B streptococcal strains for longitudinal infection studies
Inês Lorga1,2, Rafaela Geraldo1,3, Joana Soares2
1ICBAS - Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal.
Insights
Developing new bioluminescent Group B Streptococcus (GBS) strains is crucial for studying neonatal disease. Genetically engineered GBS strains enable non-invasive, in vivo monitoring of infection progression and treatment efficacy.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Biotechnology
Background:
- Group B Streptococcus (GBS) is a primary cause of invasive neonatal disease, leading to significant mortality and morbidity.
- Current treatment strategies primarily focus on antibacterials, highlighting the urgent need for novel therapeutic approaches.
- A major obstacle in GBS research is the absence of non-invasive technologies for longitudinal in vivo studies.
Purpose of the Study:
- To develop and evaluate three distinct bioluminescent Group B Streptococcus (GBS) strains for in vivo pathogenic analysis.
- To compare the efficacy of different bioluminescence systems (luxABCDE operon and firefly luciferase) for tracking GBS infections in a preclinical model.
- To establish a non-invasive imaging tool for assessing GBS disease progression and evaluating potential treatments.
Main Methods:
- Construction of three bioluminescent GBS strains: luxGBS-CC17 (luxABCDE operon on a replicative vector), fflucGBS-CC17 (red-shifted firefly luciferase on a replicative vector), and glucGBS-CC17 (luciferase integrated into the bacterial genome).
- In vitro and in vivo (infected mouse pups) assessment of bioluminescent signal intensity and stability.
- Comparison of signal output across different infection routes (haematological and vertical transmission).
Main Results:
- The luxGBS-CC17 strain showed suitability for in vitro analysis but lacked sufficient signal in vivo.
- The fflucGBS-CC17 strain provided a strong bioluminescent signal proportional to organ colonization, though vector stability varied with infection route.
- The glucGBS-CC17 strain, with chromosomally integrated luciferase, demonstrated significant bioluminescence in both infection models, correlating with high systemic colonization.
Conclusions:
- Stable chromosomal integration of luciferase (glucGBS-CC17) offers a reliable method for non-invasive, in vivo monitoring of GBS infection.
- These engineered GBS strains facilitate preclinical evaluation of therapeutic interventions against invasive neonatal disease.
- The developed bioluminescent imaging approach addresses the need for longitudinal studies in GBS pathogenesis research.
Abstract:
Group B Streptococcus (GBS) remains the leading bacterial cause of invasive neonatal disease, resulting in substantial morbidity and mortality. New therapeutic approaches beyond antibacterial treatment to prevent neonatal disease outcomes are urgent. One significant limitation in studying GBS disease and progression is the lack of non-invasive technologies for longitudinal studies. Here, we develop and compare three bioluminescent GBS strains for in vivo pathogenic analysis. Bioluminescence is based on the luxABCDE operon on a replicative vector (luxGBS-CC17), and the red-shifted firefly luciferase on a replicative vector (fflucGBS-CC17) or integrated in the genome (glucGBS-CC17). We show that luxGBS-CC17 is suitable for in vitro analysis but does not produce a significant bioluminescent signal in infected pups. In contrast, the fflucGBS-CC17 results in a strong bioluminescent signal proportional to the organ colonisation level. However, the stability of the replicative vector depends on the route of infection, especially when pups acquire the bacteria from infected vaginal mucosa. Stable chromosomal integration of luciferase in glucGBS-CC17 leads to significant bioluminescence in both haematological and vertical infection models associated with high systemic colonisation. These strains will allow the preclinical evaluation of treatment efficacy against GBS invasive disease using whole-mouse bioluminescence imaging.
