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Wang Y, Zeng M, Xia L, Valerie Olovo C, Su Z, Zhang Y. Bacterial strategies for immune systems - Role of the type VI secretion system. Int Immunopharmacol 2023; 114:109550. [PMID: 36525796 DOI: 10.1016/j.intimp.2022.109550] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 11/09/2022] [Accepted: 12/02/2022] [Indexed: 12/15/2022]
Abstract
The process of host infection by bacteria is complicated. Bacterial infections strongly induce the host immune system, which necessitates a robust clearance of the infection. However, bacteria have over time developed strategies that enable their evasion of attacks by the host immune system. One such strategy is the type VI secretion system (T6SS), a special needle-like secretion system that is widespread in Gram-negative bacteria and is responsible for delivering effector proteins into the external bacterial environment or directly into the host cell cytosol. Bacterial T6SS and its secreted effector proteins play an important role in the interaction between bacteria and host immune system. They also serve as antigens that are employed in the development of vaccines for clinical trials as well as future vaccine candidates. This review focuses mainly on aspects of T6SS effectors that impact the strength of the host immune system, including inflammation, autophagy, and apoptosis (silent programmed cell death). The T6SS-based vaccines are also described.
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Affiliation(s)
- Yurou Wang
- Institute for Medical Immunology of Jiangsu University, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu 212013, China; Department of Biochemistry and Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
| | - Minmin Zeng
- Department of Biochemistry and Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
| | - Lin Xia
- Department of Laboratory Medicine, Affiliated Hospital of Jiangsu University, Zhenjiang 212001, China; International Genome Center, Jiangsu University, Zhenjiang 212013, China
| | - Chinasa Valerie Olovo
- Department of Biochemistry and Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
| | - Zhaoliang Su
- Institute for Medical Immunology of Jiangsu University, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu 212013, China; International Genome Center, Jiangsu University, Zhenjiang 212013, China
| | - Ying Zhang
- Institute for Medical Immunology of Jiangsu University, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu 212013, China; Department of Biochemistry and Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China.
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2
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Oslan SNH, Yusoff AH, Mazlan M, Lim SJ, Khoo JJ, Oslan SN, Ismail A. Comprehensive approaches for the detection of Burkholderia pseudomallei and diagnosis of melioidosis in human and environmental samples. Microb Pathog 2022; 169:105637. [PMID: 35710088 DOI: 10.1016/j.micpath.2022.105637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 06/06/2022] [Accepted: 06/10/2022] [Indexed: 11/16/2022]
Abstract
Melioidosis is endemic in Southeast Asia and northern Australia. The causative agent of melioidosis is a Gram-negative bacterium, Burkholderia pseudomallei. Its invasion can be fatal if melioidosis is not treated promptly. It is intrinsically resistant to a variety of antibiotics. In this paper, we present a comprehensive overview of the current trends on melioidosis cases, treatments, B. pseudomallei virulence factors, and molecular techniques to detect the bacterium from different samples. The clinical and microbial diagnosis methods of identification and detection of B. pseudomallei are commonly used for the rapid diagnosis and typing of strains, such as polymerase chain reaction or multi-locus sequence typing. The genotyping strategies and techniques have been constantly evolving to identify genomic loci linked to or associated with this human disease. More research strategies for detecting and controlling melioidosis should be encouraged and conducted to understand the current situation. In conclusion, we review existing diagnostic methodologies for melioidosis detection and provide insights on prospective diagnostic methods for the bacterium.
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Affiliation(s)
- Siti Nur Hazwani Oslan
- Faculty of Food Science and Nutrition, Universiti Malaysia Sabah, Jalan UMS, 88400, Kota Kinabalu, Sabah, Malaysia.
| | - Abdul Hafidz Yusoff
- Gold Rare Earth and Material Technopreneurship Centre (GREAT), Faculty of Bioengineering and Technology, Universiti Malaysia Kelantan, Jeli Campus, Jeli, 17600, Kelantan, Malaysia.
| | - Mazlina Mazlan
- Department of Veterinary Pathology and Microbiology, Faculty of Veterinary Medicine, 43400 UPM, Serdang, Selangor, Malaysia.
| | - Si Jie Lim
- Enzyme Technology and X-Ray Crystallography Laboratory, VacBio 5, Institute of Bioscience, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia; Enzyme and Microbial Technology (EMTech) Research Centre, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.
| | - Jing Jing Khoo
- Tropical Infectious Diseases Research and Education Centre (TIDREC), High Impact Research Building, University of Malaya, 50603, Kuala Lumpur, Malaysia.
| | - Siti Nurbaya Oslan
- Enzyme Technology and X-Ray Crystallography Laboratory, VacBio 5, Institute of Bioscience, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia; Enzyme and Microbial Technology (EMTech) Research Centre, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia; Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.
| | - Aziah Ismail
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 16150, Kubang Kerian, Kelantan, Malaysia.
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3
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Roe C, Vazquez AJ, Phillips PD, Allender CJ, Bowen RA, Nottingham RD, Doyle A, Wongsuwan G, Wuthiekanun V, Limmathurotsakul D, Peacock S, Keim P, Tuanyok A, Wagner DM, Sahl JW. Multiple phylogenetically-diverse, differentially-virulent Burkholderia pseudomallei isolated from a single soil sample collected in Thailand. PLoS Negl Trop Dis 2022; 16:e0010172. [PMID: 35143500 PMCID: PMC8865643 DOI: 10.1371/journal.pntd.0010172] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 02/23/2022] [Accepted: 01/14/2022] [Indexed: 11/24/2022] Open
Abstract
Burkholderia pseudomallei is a soil-dwelling bacterium endemic to Southeast Asia and northern Australia that causes the disease, melioidosis. Although the global genomic diversity of clinical B. pseudomallei isolates has been investigated, there is limited understanding of its genomic diversity across small geographic scales, especially in soil. In this study, we obtained 288 B. pseudomallei isolates from a single soil sample (~100g; intensive site 2, INT2) collected at a depth of 30cm from a site in Ubon Ratchathani Province, Thailand. We sequenced the genomes of 169 of these isolates that represent 7 distinct sequence types (STs), including a new ST (ST1820), based on multi-locus sequence typing (MLST) analysis. A core genome SNP phylogeny demonstrated that all identified STs share a recent common ancestor that diverged an estimated 796-1260 years ago. A pan-genomics analysis demonstrated recombination between clades and intra-MLST phylogenetic and gene differences. To identify potential differential virulence between STs, groups of BALB/c mice (5 mice/isolate) were challenged via subcutaneous injection (500 CFUs) with 30 INT2 isolates representing 5 different STs; over the 21-day experiment, eight isolates killed all mice, 2 isolates killed an intermediate number of mice (1-2), and 20 isolates killed no mice. Although the virulence results were largely stratified by ST, one virulent isolate and six attenuated isolates were from the same ST (ST1005), suggesting that variably conserved genomic regions may contribute to virulence. Genomes from the animal-challenged isolates were subjected to a bacterial genome-wide association study to identify genomic regions associated with differential virulence. One associated region is a unique variant of Hcp1, a component of the type VI secretion system, which may result in attenuation. The results of this study have implications for comprehensive sampling strategies, environmental exposure risk assessment, and understanding recombination and differential virulence in B. pseudomallei.
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Affiliation(s)
- Chandler Roe
- The Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Adam J. Vazquez
- The Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Paul D. Phillips
- The Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Chris J. Allender
- The Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Richard A. Bowen
- Department of Biological Sciences, Colorado State University, Ft. Collins, Colorado, United States of America
| | - Roxanne D. Nottingham
- The Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Adina Doyle
- The Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Gumphol Wongsuwan
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
| | - Vanaporn Wuthiekanun
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
| | | | - Sharon Peacock
- Department of Medicine, University of Cambridge, Cambridge, England
| | - Paul Keim
- The Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Apichai Tuanyok
- The Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - David M. Wagner
- The Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Jason W. Sahl
- The Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
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4
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Mariappan V, Vellasamy KM, Barathan M, Girija ASS, Shankar EM, Vadivelu J. Hijacking of the Host's Immune Surveillance Radars by Burkholderia pseudomallei. Front Immunol 2021; 12:718719. [PMID: 34456925 PMCID: PMC8384953 DOI: 10.3389/fimmu.2021.718719] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 07/12/2021] [Indexed: 11/20/2022] Open
Abstract
Burkholderia pseudomallei (B. pseudomallei) causes melioidosis, a potentially fatal disease for which no licensed vaccine is available thus far. The host-pathogen interactions in B. pseudomallei infection largely remain the tip of the iceberg. The pathological manifestations are protean ranging from acute to chronic involving one or more visceral organs leading to septic shock, especially in individuals with underlying conditions similar to COVID-19. Pathogenesis is attributed to the intracellular ability of the bacterium to ‘step into’ the host cell’s cytoplasm from the endocytotic vacuole, where it appears to polymerize actin filaments to spread across cells in the closer vicinity. B. pseudomallei effectively evades the host’s surveillance armory to remain latent for prolonged duration also causing relapses despite antimicrobial therapy. Therefore, eradication of intracellular B. pseudomallei is highly dependent on robust cellular immune responses. However, it remains ambiguous why certain individuals in endemic areas experience asymptomatic seroconversion, whereas others succumb to sepsis-associated sequelae. Here, we propose key insights on how the host’s surveillance radars get commandeered by B. pseudomallei.
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Affiliation(s)
- Vanitha Mariappan
- Center for Toxicology and Health Risk Studies, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Kumutha Malar Vellasamy
- Department of Medical Microbiology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Muttiah Barathan
- Department of Medical Microbiology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - A S Smiline Girija
- Department of Microbiology, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences (SIMATS), Chennai, India
| | - Esaki M Shankar
- Infection Biology, Department of Life Sciences, Central University of Tamil Nadu, Thiruvarur, India
| | - Jamuna Vadivelu
- Department of Medical Microbiology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
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5
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Loaiza CD, Duhan N, Lister M, Kaundal R. In silico prediction of host-pathogen protein interactions in melioidosis pathogen Burkholderia pseudomallei and human reveals novel virulence factors and their targets. Brief Bioinform 2020; 22:5842243. [PMID: 32444871 DOI: 10.1093/bib/bbz162] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 11/13/2019] [Accepted: 11/20/2019] [Indexed: 12/13/2022] Open
Abstract
The aerobic, Gram-negative motile bacillus, Burkholderia pseudomallei is a facultative intracellular bacterium causing melioidosis, a critical disease of public health importance, which is widely endemic in the tropics and subtropical regions of the world. Melioidosis is associated with high case fatality rates in animals and humans; even with treatment, its mortality is 20-50%. It also infects plants and is designated as a biothreat agent. B. pseudomallei is pathogenic due to its ability to invade, resist factors in serum and survive intracellularly. Despite its importance, to date only a few effector proteins have been functionally characterized, and there is not much information regarding the host-pathogen protein-protein interactions (PPI) of this system, which are important to studying infection mechanisms and thereby develop prevention measures. We explored two computational approaches, the homology-based interolog and the domain-based method, to predict genome-scale host-pathogen interactions (HPIs) between two different strains of B. pseudomallei (prototypical, and highly virulent) and human. In total, 76 335 common HPIs (between the two strains) were predicted involving 8264 human and 1753 B. pseudomallei proteins. Among the unique PPIs, 14 131 non-redundant HPIs were found to be unique between the prototypical strain and human, compared to 3043 non-redundant HPIs between the highly virulent strain and human. The protein hubs analysis showed that most B. pseudomallei proteins formed a hub with human dnaK complex proteins associated with tuberculosis, a disease similar in symptoms to melioidosis. In addition, drug-binding and carbohydrate-binding mechanisms were found overrepresented within the host-pathogen network, and metabolic pathways were frequently activated according to the pathway enrichment. Subcellular localization analysis showed that most of the pathogen proteins are targeting human proteins inside cytoplasm and nucleus. We also discovered the host targets of the drug-related pathogen proteins and proteins that form T3SS and T6SS in B. pseudomallei. Additionally, a comparison between the unique PPI patterns present in the prototypical and highly virulent strains was performed. The current study is the first report on developing a genome-scale host-pathogen protein interaction networks between the human and B. pseudomallei, a critical biothreat agent. We have identified novel virulence factors and their interacting partners in the human proteome. These PPIs can be further validated by high-throughput experiments and may give new insights on how B. pseudomallei interacts with its host, which will help medical researchers in developing better prevention measures.
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Affiliation(s)
- Cristian D Loaiza
- Center for Integrated BioSystems/Department of Plants, Soils, and Climate, College of Agriculture and Applied Sciences, Utah State University, USA
| | - Naveen Duhan
- Center for Integrated BioSystems/Department of Plants, Soils, and Climate, College of Agriculture and Applied Sciences, Utah State University, USA
| | - Matthew Lister
- Bioinformatics Facility, Center for Integrated BioSystems, Utah State University, USA
| | - Rakesh Kaundal
- Department of Plants, Soils, and Climate/Center for Integrated BioSystems, College of Agriculture and Applied Sciences, Utah State University, Logan, UT 84322 USA
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6
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Price EP, Viberg LT, Kidd TJ, Bell SC, Currie BJ, Sarovich DS. Transcriptomic analysis of longitudinal Burkholderia pseudomallei infecting the cystic fibrosis lung. Microb Genom 2018; 4. [PMID: 29989529 PMCID: PMC6159556 DOI: 10.1099/mgen.0.000194] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The melioidosis bacterium, Burkholderia pseudomallei, is increasingly being recognised as a pathogen in patients with cystic fibrosis (CF). We have recently catalogued genome-wide variation of paired, isogenic B. pseudomallei isolates from seven Australasian CF cases, which were collected between 4 and 55 months apart. Here, we extend this investigation by documenting the transcriptomic changes in B. pseudomallei in five cases. Following growth in an artificial CF sputum medium, four of the five paired isolates exhibited significant differential gene expression (DE) that affected between 32 and 792 genes. The greatest number of DE events was observed between the strains from patient CF9, consistent with the hypermutator status of the latter strain, which is deficient in the DNA mismatch repair protein MutS. Two patient isolates harboured duplications that concomitantly increased expression of the β-lactamase-encoding gene penA, and a 35 kb deletion in another abolished expression of 29 genes. Convergent expression profiles in the chronically-adapted isolates identified two significantly downregulated and 17 significantly upregulated loci, including the resistance-nodulation-division (RND) efflux pump BpeEF-OprC, the quorum-sensing hhqABCDE operon, and a cyanide- and pyocyanin-insensitive cytochrome bd quinol oxidase. These convergent pathoadaptations lead to increased expression of pathways that may suppress competing bacterial and fungal pathogens, and that enhance survival in oxygen-restricted environments, the latter of which may render conventional antibiotics less effective in vivo. Treating chronically adapted B. pseudomallei infections with antibiotics designed to target anaerobic infections, such as the nitroimidazole class of antibiotics, may significantly improve pathogen eradication attempts by exploiting this Achilles heel.
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Affiliation(s)
- Erin P Price
- 1Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Sippy Downs, QLD, Australia.,2Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia
| | - Linda T Viberg
- 2Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia
| | - Timothy J Kidd
- 3Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia.,4School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, Australia
| | - Scott C Bell
- 3Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia.,5QIMR Berghofer Medical Research Institute, Herston, QLD, Australia.,6Department of Thoracic Medicine, The Prince Charles Hospital, Chermside, QLD, Australia
| | - Bart J Currie
- 2Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia.,7Department of Infectious Diseases and Northern Territory Medical Program, Royal Darwin Hospital, Darwin, Northern Territory, Australia
| | - Derek S Sarovich
- 1Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Sippy Downs, QLD, Australia.,2Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia
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Abstract
Purpose of review Burkholderia mallei is a facultative intracellular pathogen that causes the highly contagious and often the fatal disease, glanders. With its high rate of infectivity via aerosol and recalcitrance toward antibiotics, this pathogen is considered a potential biological threat agent. This review focuses on the most recent literature highlighting host innate immune response to B. mallei. Recent findings Recent studies focused on elucidating host innate immune responses to the novel mechanisms and virulence factors employed by B. mallei for survival. Studies suggest that pathogen proteins manipulate various cellular processes, including host ubiquitination pathways, phagosomal escape, and actin–cytoskeleton rearrangement. Immune-signaling molecules such as Toll-like receptors, nucleotode-binding oligomerization domain, myeloid differentiation primary response protein 88, and proinflammatory cytokines such as interferon-gamma and tumor necrosis factor-α, play key roles in the induction of innate immune responses. Modifications in B. mallei lipopolysaccharide, in particular, the lipid A acyl groups, stimulate immune responses via Toll-like receptor4 activation that may contribute to persistent infection. Summary Mortality is high because of septicemia and immune pathogenesis with B. mallei exposure. An effective innate immune response is critical to controlling the acute phase of the infection. Both vaccination and therapeutic approaches are necessary for complete protection against B. mallei.
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Kang WT, Vellasamy KM, Vadivelu J. Eukaryotic pathways targeted by the type III secretion system effector protein, BipC, involved in the intracellular lifecycle of Burkholderia pseudomallei. Sci Rep 2016; 6:33528. [PMID: 27634329 PMCID: PMC5025855 DOI: 10.1038/srep33528] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 08/24/2016] [Indexed: 12/15/2022] Open
Abstract
Burkholderia pseudomallei, the etiological agent for melioidosis, is known to secrete a type III secretion system (TTSS) protein into the host’s internal milieu. One of the TTSS effector protein, BipC, has been shown to play an important role in the B. pseudomallei pathogenesis. To identify the host response profile that was directly or indirectly regulated by this protein, genome-wide transcriptome approach was used to examine the gene expression profiles of infected mice. The transcriptome analysis of the liver and spleen revealed that a total of approximately 1,000 genes were transcriptionally affected by BipC. Genes involved in bacterial invasion, regulation of actin cytoskeleton, and MAPK signalling pathway were over-expressed and may be specifically regulated by BipC in vivo. These results suggest that BipC mainly targets pathways related to the cellular processes which could modulate the cellular trafficking processes. The host transcriptional response exhibited remarkable differences with and without the presence of the BipC protein. Overall, the detailed picture of this study provides new insights that BipC may have evolved to efficiently manipulate host-cell pathways which is crucial in the intracellular lifecycle of B. pseudomallei.
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Affiliation(s)
- Wen-Tyng Kang
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Kumutha Malar Vellasamy
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Jamuna Vadivelu
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia
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Deen NS, Gong L, Naderer T, Devenish RJ, Kwok T. Analysis of the Relative Contribution of Phagocytosis, LC3-Associated Phagocytosis, and Canonical Autophagy During Helicobacter pylori Infection of Macrophages. Helicobacter 2015; 20:449-59. [PMID: 25864465 DOI: 10.1111/hel.12223] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND Previous findings have suggested that Helicobacter pylori induces autophagic processes and subsequently takes refuge in autophagosomes, thereby contributing to persistent infection. Recently, a noncanonical form of autophagy, LC3 (microtubule-associated protein 1 light chain 3)-associated phagocytosis (LAP), has been shown to be required for efficient clearance of some intracellular bacteria. Whether H. pylori infection induces LAP had not been examined previously. In this study, we determined the extent to which H. pylori infection induces canonical autophagy or LAP in macrophages, and the involvement of the H. pylori cag pathogenicity island (cagPAI) with these processes. METHODS Immunofluorescence confocal microscopy was used to analyze the formation of GFP-LC3 puncta and their colocalization with H. pylori. Transmission electron microscopy was used to detect the ultrastructure of H. pylori-containing compartments. RESULTS The majority of intracellular bacteria (85-95%) were found in phagosomes that were LC3-negative, with a small proportion (4-14%) appearing "free" in the cytosol. Only a very small percentage (0.5-6%) of intracellular H. pylori was sequestered in autophagosomes. Furthermore, no statistically significant difference in the relative distribution of H. pylori in the various compartments was observed between wild-type and cagPAI-mutant bacteria. CONCLUSIONS In macrophages, H. pylori infection does not induce LAP, but can induce canonical autophagy, which entraps a very small fraction of intracellular bacteria. We propose that this subpopulation of intracellular H. pylori might have escaped from phagosomes into the cytosol before being sequestered by autophagosomes. The cagPAI of H. pylori has only minor influence, if any, on the extent of these processes.
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Affiliation(s)
- Nadia S Deen
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic., Australia
| | - Lan Gong
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic., Australia
| | - Thomas Naderer
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic., Australia
| | - Rodney J Devenish
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic., Australia
| | - Terry Kwok
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic., Australia.,Department of Microbiology, Monash University, Clayton, Vic., Australia
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10
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Steele S, Brunton J, Kawula T. The role of autophagy in intracellular pathogen nutrient acquisition. Front Cell Infect Microbiol 2015; 5:51. [PMID: 26106587 PMCID: PMC4460576 DOI: 10.3389/fcimb.2015.00051] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 05/26/2015] [Indexed: 01/01/2023] Open
Abstract
Following entry into host cells intracellular pathogens must simultaneously evade innate host defense mechanisms and acquire energy and anabolic substrates from the nutrient-limited intracellular environment. Most of the potential intracellular nutrient sources are stored within complex macromolecules that are not immediately accessible by intracellular pathogens. To obtain nutrients for proliferation, intracellular pathogens must compete with the host cell for newly-imported simple nutrients or degrade host nutrient storage structures into their constituent components (fatty acids, carbohydrates, and amino acids). It is becoming increasingly evident that intracellular pathogens have evolved a wide variety of strategies to accomplish this task. One recurrent microbial strategy is to exploit host degradative processes that break down host macromolecules into simple nutrients that the microbe can use. Herein we focus on how a subset of bacterial, viral, and eukaryotic pathogens leverage the host process of autophagy to acquire nutrients that support their growth within infected cells.
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Affiliation(s)
- Shaun Steele
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina Chapel Hill, NC, USA
| | - Jason Brunton
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina Chapel Hill, NC, USA
| | - Thomas Kawula
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina Chapel Hill, NC, USA
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11
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Devenish RJ, Lai S. Autophagy and Burkholderia. Immunol Cell Biol 2014; 93:18-24. [DOI: 10.1038/icb.2014.87] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 09/11/2014] [Accepted: 09/16/2014] [Indexed: 12/26/2022]
Affiliation(s)
- Rodney J Devenish
- Department of Biochemistry and Molecular Biology, Monash University, Clayton CampusMelbourneVICAustralia
| | - Shu‐chin Lai
- Department of Biochemistry and Molecular Biology, Monash University, Clayton CampusMelbourneVICAustralia
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12
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Stone JK, DeShazer D, Brett PJ, Burtnick MN. Melioidosis: molecular aspects of pathogenesis. Expert Rev Anti Infect Ther 2014; 12:1487-99. [PMID: 25312349 DOI: 10.1586/14787210.2014.970634] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Burkholderia pseudomallei is a gram-negative bacterium that causes melioidosis, a multifaceted disease that is highly endemic in southeast Asia and northern Australia. This facultative intracellular pathogen possesses a large genome that encodes a wide array of virulence factors that promote survival in vivo by manipulating host cell processes and disarming elements of the host immune system. Antigens and systems that play key roles in B. pseudomallei virulence include capsular polysaccharide, lipopolysaccharide, adhesins, specialized secretion systems, actin-based motility and various secreted factors. This review provides an overview of the current and steadily expanding knowledge regarding the molecular mechanisms used by this organism to survive within a host and their contribution to the pathogenesis of melioidosis.
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Affiliation(s)
- Joshua K Stone
- Department of Microbiology and Immunology, University of South Alabama, 610 Clinic Drive, Mobile, AL 36688, USA
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13
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Biggins JB, Kang HS, Ternei MA, DeShazer D, Brady SF. The chemical arsenal of Burkholderia pseudomallei is essential for pathogenicity. J Am Chem Soc 2014; 136:9484-90. [PMID: 24884988 PMCID: PMC4091270 DOI: 10.1021/ja504617n] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
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Increasing evidence has shown that
small-molecule chemistry in
microbes (i.e., secondary metabolism) can modulate the microbe–host
response in infection and pathogenicity. The bacterial disease melioidosis
is conferred by the highly virulent, antibiotic-resistant pathogen Burkholderia pseudomallei (BP). Whereas
some macromolecular structures have been shown to influence BP virulence (e.g., secretion systems, cellular capsule,
pili), the role of the large cryptic secondary metabolome encoded
within its genome has been largely unexplored for its importance to
virulence. Herein we demonstrate that BP-encoded
small-molecule biosynthesis is indispensible for in vivo BP pathogenicity. Promoter exchange experiments were used to induce
high-level molecule production from two gene clusters (MPN and SYR)
found to be essential for in vivo virulence. NMR
structural characterization of these metabolites identified a new
class of lipopeptide biosurfactants/biofilm modulators (the
malleipeptins) and syrbactin-type proteasome inhibitors, both
of which represent overlooked small-molecule virulence factors for BP. Disruption of Burkholderia virulence by inhibiting the
biosynthesis of these small-molecule biosynthetic pathways may prove
to be an effective strategy for developing novel melioidosis-specific
therapeutics.
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Affiliation(s)
- John B Biggins
- Laboratory of Genetically Encoded Small Molecules, Howard Hughes Medical Institute , The Rockefeller University , 1230 York Avenue, New York, New York 10065, United States
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