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Intracellular survival of Burkholderia pseudomallei
A L Jones1, T J Beveridge, D E Woods
1Department of Microbiology and Infectious Diseases, University of Calgary Health Sciences Centre, Alberta, Canada.
Abstract:
Burkholderia pseudomallei is the causative agent of melioidosis, a disease being increasingly recognized as an important cause of morbidity and mortality in many regions of the world. Several features of melioidosis suggest that B. pseudomallei is a facultative intracellular pathogen. This study was designed to assess the ability of B. pseudomallei to invade and survive in eukaryotic cells. We have shown that B. pseudomallei has the capacity to invade cultured cell lines, including HeLa, CHO, A549, and Vero cells. We have demonstrated intracellular survival of B. pseudomallei in professional phagocytic cells, including rat alveolar macrophages. B pseudomallei was localized inside vacuoles in human monocyte-like U937 cells, a histiocytic lymphoma cell line with phagocytic properties. Additionally, electron microscopic visualization of B. pseudomallei-infected HeLa cells and polymorphonuclear leukocytes confirmed the presence of intracellular bacteria within membrane-bound vacuoles. B. pseudomallei was found to be resistant to the cationic peptide protamine and to purified human defensin HNP-1.
Insights
Burkholderia pseudomallei, the cause of melioidosis, can invade and survive within host eukaryotic cells. This bacterium was found to be resistant to key antimicrobial peptides, highlighting its potential as an intracellular pathogen.
Area of Science:
- Microbiology
- Cell Biology
- Pathogen Research
Background:
- Melioidosis, caused by Burkholderia pseudomallei, is a significant global health concern.
- Clinical features suggest B. pseudomallei acts as a facultative intracellular pathogen.
Purpose of the Study:
- To investigate the capacity of B. pseudomallei to invade and survive within eukaryotic host cells.
- To determine the intracellular localization and resistance mechanisms of B. pseudomallei.
Main Methods:
- Invasion assays using various cultured cell lines (HeLa, CHO, A549, Vero).
- Intracellular survival studies in professional phagocytic cells (rat alveolar macrophages, U937 cells).
- Electron microscopy for visualizing intracellular bacteria and resistance testing against antimicrobial peptides (protamine, defensin HNP-1).
Main Results:
- B. pseudomallei successfully invaded multiple eukaryotic cell lines.
- Intracellular survival was demonstrated in phagocytic cells, with bacteria localized within vacuoles.
- Electron microscopy confirmed intracellular bacteria within membrane-bound vacuoles in HeLa cells and polymorphonuclear leukocytes.
- B. pseudomallei exhibited resistance to protamine and human defensin HNP-1.
Conclusions:
- B. pseudomallei possesses the ability to invade host cells and survive intracellularly, supporting its role as a facultative intracellular pathogen.
- Intracellular B. pseudomallei resides within vacuoles and demonstrates resistance to specific host defense peptides, contributing to its pathogenesis.