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Updated: Apr 20, 2026
Immuno-fluorescence Assay of Leptospiral Surface-exposed Proteins
Published on: July 1, 2011
Carboxyfluorescein diacetate succinimidyl ester labeling method to study the interaction between Leptospira and
Boyu Liu1, Yanchun Wang, Xiaokui Guo
1Department of Immunology and Microbiology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China. liuboyu2014@163.com
Abstract:
Leptospirosis, which is caused by pathogenic species of the genus Leptospira, has emerged as one of the most widespread zoonotic diseases in the world. The exact mechanism of pathogenesis remains unknown, and the interaction between Leptospira and macrophages is not well understood. In this study, we report that carboxyfluorescein diacetate succinimidyl ester (CFDA-SE) can efficiently label different Leptospira interrogans strains without affecting bacterial motility, viability, or virulence. Following co-incubation, CFDA-SE-labeled leptospires associated with macrophages were quantified by flow cytometry or confocal microscopy. In addition, we showed that trypan blue efficiently quenched the extracellular fluorescence from the adherent leptospires, which enabled intracellular and extracellular bacteria to be distinguished.
Insights
Researchers developed a new method to track Leptospira bacteria using CFDA-SE labeling. This technique allows for better understanding of how Leptospira interrogans interacts with macrophages, aiding leptospirosis research.
Area of Science:
- Microbiology
- Immunology
- Infectious Diseases
Background:
- Leptospirosis is a significant global zoonotic disease caused by Leptospira.
- The pathogenesis of Leptospira and its interaction with host immune cells, particularly macrophages, are not fully understood.
Purpose of the Study:
- To develop and validate a reliable method for labeling Leptospira interrogans strains.
- To investigate the association of labeled Leptospira with macrophages.
- To differentiate between intracellular and extracellular bacteria.
Main Methods:
- Labeling of Leptospira interrogans with carboxyfluorescein diacetate succinimidyl ester (CFDA-SE).
- Assessment of labeling effects on bacterial motility, viability, and virulence.
- Quantification of Leptospira-macrophage association using flow cytometry and confocal microscopy.
- Use of trypan blue to quench extracellular fluorescence for distinguishing intracellular bacteria.
Main Results:
- CFDA-SE labeling efficiently marked various Leptospira interrogans strains without compromising bacterial characteristics.
- The method allowed for accurate quantification of Leptospira association with macrophages.
- Trypan blue quenching effectively distinguished between intracellular and extracellular bacteria.
Conclusions:
- CFDA-SE labeling is a robust tool for studying Leptospira-macrophage interactions.
- This technique facilitates a deeper understanding of leptospirosis pathogenesis.
- The developed method aids in the study of zoonotic bacterial infections.
