title: Carboxyfluorescein diacetate succinimidyl ester labeling method to  study the interaction between Leptospira and macrophages.
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.
authors.affiliation: Department of Immunology and Microbiology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China. liuboyu2014@163.com
authors.forename: Boyu
authors.initials: B
authors.lastname: Liu
authors.forename: Yanchun
authors.initials: Y
authors.lastname: Wang
authors.forename: Xiaokui
authors.initials: X
authors.lastname: Guo
authors.forename: Weinan
authors.initials: W
authors.lastname: Zhu
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Ping
authors.initials: P
authors.lastname: He
mesh_terms: D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D005434:Flow Cytometry; D005452:Fluoresceins / Q000737:chemistry; D054884:Host-Pathogen Interactions; D007919:Leptospira / Q000737:chemistry / Q000276:immunology*; D007922:Leptospirosis / Q000276:immunology* / Q000382:microbiology* / Q000473:pathology; D008168:Lung / Q000382:microbiology / Q000473:pathology; D008264:Macrophages / Q000276:immunology* / Q000382:microbiology*; D051379:Mice; D018613:Microscopy, Confocal; D013194:Staining and Labeling / Q000379:methods*; D013388:Succinimides / Q000737:chemistry
chemical_list: C087165:5-(6)-carboxyfluorescein diacetate succinimidyl ester; D005452:Fluoresceins; D013388:Succinimides