Researchers have developed a revolutionary technique to study Group B Streptococcus (GBS) infections using bioluminescent reporter strains. GBS is the leading cause of severe neonatal infections, resulting in high mortality and lifelong complications. This new approach allows scientists to non-invasively track the progression of GBS disease in living animals, paving the way for better understanding of the infection and development of new treatments.
Shedding Light on Deadly Bacterial Infections
Group B Streptococcus (GBS) is a major threat to newborn babies, causing life-threatening infections like meningitis and sepsis. Despite improvements in treatment, GBS remains the leading cause of invasive bacterial disease in infants, with high mortality rates and significant long-term neurological consequences for survivors. Studying the progression of these infections has been challenging, as traditional methods rely on euthanizing animals to track bacterial colonization in different organs.
Bioluminescent Bacteria: A Game-Changer for Infection Research
To overcome this limitation, a team of researchers from Portugal and France set out to develop bioluminescent strains of GBS. By engineering the bacteria to produce light, the scientists can now non-invasively monitor the infection in living animals using specialized imaging techniques.
The researchers created three different bioluminescent GBS strains, each with unique properties:
1. luxGBS-CC17: This strain uses the luciferase enzyme from fireflies to produce light. While it worked well in vitro, the strain failed to produce a strong enough signal to be detected in infected animals.
2. fflucGBS-CC17: This strain uses a red-shifted variant of the firefly luciferase, which emits light at a longer wavelength that can better penetrate tissues. The researchers found this strain was effective for short-term infection studies, but the bioluminescent plasmid was not stable enough for long-term monitoring.
A Stable, Chromosomal Approach
To address the stability issue, the team developed a third strain, glucGBS-CC17, where the luciferase gene was integrated directly into the bacterial chromosome. This ensures the reporter is maintained as the bacteria replicate, making it suitable for long-term studies of GBS disease progression.
The researchers demonstrated that the glucGBS-CC17 strain reliably produced bioluminescent signals that correlated with the level of bacterial colonization in different organs, including the brain, lungs, and liver. This allowed them to non-invasively track the infection in living mice, revealing valuable insights into the pathogenesis of GBS.
Paving the Way for Improved Treatments
The availability of these bioluminescent GBS strains represents a significant breakthrough for the field of neonatal infectious disease research. By enabling researchers to monitor the infection in real-time, without the need to euthanize animals, the new method aligns with the principles of the 3Rs (Replacement, Reduction, and Refinement) in animal experimentation.
Moreover, these bioluminescent GBS strains will be invaluable tools for evaluating the efficacy of new preventive and therapeutic approaches against this deadly infection, ultimately leading to improved outcomes for newborns affected by GBS disease.
Author credit: This article is based on research by Inês Lorga, Rafaela Geraldo, Joana Soares, Liliana Oliveira, Arnaud Firon, Elva Bonifácio Andrade.
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