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Updated: Aug 25, 2026
Live Cell Imaging of Bacillus subtilis and Streptococcus pneumoniae using Automated Time-lapse Microscopy
Published on: July 28, 2011
Time-lapse confocal imaging of development of Bacillus anthracis in macrophages
Gordon Ruthel1, Wilson J Ribot, Sina Bavari
1Clinical Research Management, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland 21702, USA. gordon.ruthel@amedd.army.mil.
Abstract:
Macrophages attempt to battle infection with Bacillus anthracis spores by phagocytosis of the spores. However, it is believed that B. anthracis spores may survive phagocytosis and may actually use the macrophages that ingest them as a means of transport to lymph nodes. Thus far, the events that occur after spores undergo phagocytosis have remained unclear. To elucidate the fate of spores internalized by macrophages, we have used time-lapse confocal microscopy to follow individual fluorescent spores over time. By use of this method, we have determined that some phagocytized spores survive beyond germination, to become bacilli that then replicate within the macrophages.
Insights
Bacillus anthracis spores can survive macrophage ingestion and replicate inside host cells. This study reveals that infected macrophages may serve as a transport system for anthrax bacilli to spread within the body.
Area of Science:
- Microbiology
- Immunology
- Cell Biology
Background:
- Macrophages are key immune cells involved in combating bacterial infections like Bacillus anthracis.
- It is hypothesized that Bacillus anthracis spores may evade phagocytosis and utilize macrophages for dissemination to lymph nodes.
- The intracellular fate of Bacillus anthracis spores post-phagocytosis remains largely unknown.
Purpose of the Study:
- To investigate the survival and replication of Bacillus anthracis spores within macrophages after phagocytosis.
- To elucidate the intracellular events following macrophage-spore interaction.
Main Methods:
- Utilized time-lapse confocal microscopy to track individual fluorescently labeled Bacillus anthracis spores.
- Observed the behavior and fate of spores within macrophages over time.
Main Results:
- Demonstrated that some phagocytized Bacillus anthracis spores survive the germination process within macrophages.
- Confirmed that these surviving spores develop into bacilli and replicate intracellularly.
- Revealed that macrophages can harbor replicating Bacillus anthracis bacilli.
Conclusions:
- Bacillus anthracis spores can survive and replicate inside macrophages, challenging the notion of complete phagocytic clearance.
- Macrophages may act as a Trojan horse, facilitating the spread of Bacillus anthracis bacilli within the host.
- Understanding this intracellular survival mechanism is crucial for developing effective anthrax treatments.
