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Visualizing early Mycobacterium tuberculosis interactions with murine lung macrophages using intravital imaging
Biorxiv : the Preprint Server for Biology
|March 23, 2026
Summary
Researchers developed a new intravital microscopy method to safely visualize Mycobacterium tuberculosis (Mtb) infection dynamics in mouse lungs. This breakthrough allows real-time imaging of bacterial behavior and host interactions under BSL-2 conditions.
Area of Science:
- * Microbiology
- * Immunology
- * Biomedical Imaging
Background:
- * Intravital microscopy offers real-time visualization of cellular processes in vivo.
- * Previous studies of Mycobacterium tuberculosis (Mtb) were limited by Biosafety Level 3 (BSL-3) requirements and technical challenges in lung imaging.
- * High-resolution imaging of the lung requires specialized techniques to overcome motion artifacts and ensure sample stability.
Purpose of the Study:
- * To establish a practical, safe, and high-resolution intravital microscopy protocol for studying Mtb infection in the murine lung.
- * To overcome the biosafety and technical hurdles that have previously hindered real-time imaging of Mtb in vivo.
- * To provide a foundation for mechanistic studies of mycobacterial pathogenesis and host immune responses.
Main Methods:
- * Development of a Biosafety Level 2 (BSL-2) compatible protocol using the Window for High-Resolution Imaging of the murine Lung (WHRIL).
- * Utilization of a genetically defined, triple-auxotrophic, tdTomato-expressing Mtb strain (mc² 8471) for intravenous infection.
- * Application of intravital microscopy in reporter mice to visualize bacterial dynamics post-infection.
Main Results:
- * Successful visualization of rapid bacterial entry into the pulmonary vasculature.
- * Observation of Mtb aggregation, vascular occlusion, and dissemination into the lung parenchyma.
- * Real-time imaging of macrophage uptake of Mtb over three days post-infection.
Conclusions:
- * The developed WHRIL-based protocol provides the first practical platform for real-time intravital imaging of Mtb in the lung under BSL-2 conditions.
- * This system enables detailed mechanistic studies of bacterial physiology, host recognition, and immune clearance.
- * The protocol facilitates research on mycobacterial infections using safe Mtb surrogates, paving the way for new therapeutic strategies.
