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Srivastava P, Shukla A, Singh R, Kant R, Mishra N, Behera SP, Dwivedi GR, Yadav DK. Orientia tsutsugamushi: An Unusual Intracellular Bacteria-Adaptation Strategies, Available Antibiotics, and Alternatives for Treatment. Curr Microbiol 2024; 81:236. [PMID: 38907107 DOI: 10.1007/s00284-024-03754-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 05/28/2024] [Indexed: 06/23/2024]
Abstract
During evolution Orientia tsutsugamushi became a smarter obligate bacterium to establish as intracellular pathogens. O. tsutsugamushi is a human pathogenic bacterium responsible for 1 billion infections of scrub typhus. Several novel mechanisms make this bacterium unique (cell wall, genetic constitutions, secretion system, etc.). In 2007, O. tsutsugamushi Boryong was pioneer strain for whole-genome sequencing. But the fundamental biology of this bacterial cell is a mystery till date. The unusual biology makes this organism as model for host cell interaction. Only a few antibiotics are effective against this intracellular pathogen but emergence of less susceptibility toward antibiotics make the situation alarming. The review was captivated to highlight the unusual aspects of adaptation, antibiotics, and drugs beyond antibiotics.
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Affiliation(s)
- Prashansha Srivastava
- ICMR-Regional Medical Research Centre, BRD Medical College Campus, Gorakhpur, 273013, India
| | - Aishwarya Shukla
- ICMR-Regional Medical Research Centre, BRD Medical College Campus, Gorakhpur, 273013, India
| | - Rajeev Singh
- ICMR-Regional Medical Research Centre, BRD Medical College Campus, Gorakhpur, 273013, India
| | - Rajni Kant
- ICMR-Regional Medical Research Centre, BRD Medical College Campus, Gorakhpur, 273013, India
| | - Nalini Mishra
- ICMR-Regional Medical Research Centre, BRD Medical College Campus, Gorakhpur, 273013, India
| | - Sthita P Behera
- ICMR-Regional Medical Research Centre, BRD Medical College Campus, Gorakhpur, 273013, India
| | - Gaurav R Dwivedi
- ICMR-Regional Medical Research Centre, BRD Medical College Campus, Gorakhpur, 273013, India.
| | - Dharmendra K Yadav
- College of Pharmacy, Gachon University of Medicine and Science, Hambakmoeiro 191, Yeonsu-Gu, Incheon, 21924, Korea
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Minahan NT, Yen TY, Guo YLL, Shu PY, Tsai KH. Concatenated ScaA and TSA56 Surface Antigen Sequences Reflect Genome-Scale Phylogeny of Orientia tsutsugamushi: An Analysis Including Two Genomes from Taiwan. Pathogens 2024; 13:299. [PMID: 38668254 PMCID: PMC11054523 DOI: 10.3390/pathogens13040299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 03/29/2024] [Accepted: 03/29/2024] [Indexed: 04/29/2024] Open
Abstract
Orientia tsutsugamushi is an obligate intracellular bacterium associated with trombiculid mites and is the causative agent of scrub typhus, a life-threatening febrile disease. Strain typing of O. tsutsugamushi is based on its immunodominant surface antigen, 56-kDa type-specific antigen (TSA56). However, TSA56 gene sequence-based phylogenetic analysis is only partially congruent with core genome-based phylogenetic analysis. Thus, this study investigated whether concatenated surface antigen sequences, including surface cell antigen (Sca) proteins, can reflect the genome-scale phylogeny of O. tsutsugamushi. Complete genomes were obtained for two common O. tsutsugamushi strains in Taiwan, TW-1 and TW-22, and the core genome/proteome was identified for 11 O. tsutsugamushi strains. Phylogenetic analysis was performed using maximum likelihood (ML) and neighbor-joining (NJ) methods, and the congruence between trees was assessed using a quartet similarity measure. Phylogenetic analysis based on 691 concatenated core protein sequences produced identical tree topologies with ML and NJ methods. Among TSA56 and core Sca proteins (ScaA, ScaC, ScaD, and ScaE), TSA56 trees were most similar to the core protein tree, and ScaA trees were the least similar. However, concatenated ScaA and TSA56 sequences produced trees that were highly similar to the core protein tree, the NJ tree being more similar. Strain-level characterization of O. tsutsugamushi may be improved by coanalyzing ScaA and TSA56 sequences, which are also important targets for their combined immunogenicity.
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Affiliation(s)
- Nicholas T. Minahan
- Institute of Environmental and Occupational Health Sciences, College of Public Health, National Taiwan University, Taipei 100025, Taiwan; (N.T.M.); (Y.-L.L.G.)
| | - Tsai-Ying Yen
- Centers for Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taipei 115210, Taiwan; (T.-Y.Y.); (P.-Y.S.)
| | - Yue-Liang Leon Guo
- Institute of Environmental and Occupational Health Sciences, College of Public Health, National Taiwan University, Taipei 100025, Taiwan; (N.T.M.); (Y.-L.L.G.)
- Department of Environmental and Occupational Medicine, National Taiwan University (NTU) College of Medicine and NTU Hospital, Taipei 100025, Taiwan
| | - Pei-Yun Shu
- Centers for Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taipei 115210, Taiwan; (T.-Y.Y.); (P.-Y.S.)
| | - Kun-Hsien Tsai
- Institute of Environmental and Occupational Health Sciences, College of Public Health, National Taiwan University, Taipei 100025, Taiwan; (N.T.M.); (Y.-L.L.G.)
- Global Health Program, College of Public Health, National Taiwan University, Taipei 100025, Taiwan
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3
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Fromm L, Mehl J, Keller C. Orientia tsutsugamushi: A life between escapes. Microbiologyopen 2023; 12:e1380. [PMID: 37877457 PMCID: PMC10493369 DOI: 10.1002/mbo3.1380] [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: 08/16/2023] [Accepted: 08/31/2023] [Indexed: 10/26/2023] Open
Abstract
The life cycle of the mite-borne, obligate intracellular pathogen Orientia tsutsugamushi (Ot), the causative agent of human scrub typhus, differs in many aspects from that of other members of the Rickettsiales order. Particularly, the nonlytic cellular exit of individual Ot bacteria at the plasma membrane closely resembles the budding of enveloped viruses but has only been rudimentarily studied at the molecular level. This brief article is focused on the current state of knowledge of escape events in the life cycle of Ot and highlights differences in strategies of other rickettsiae.
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Affiliation(s)
- Lea Fromm
- Institute of VirologyPhilipps University MarburgMarburgGermany
| | - Jonas Mehl
- Institute of VirologyPhilipps University MarburgMarburgGermany
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Pereira IS, Pais SV, Borges V, Borrego MJ, Gomes JP, Mota LJ. The Type III Secretion Effector CteG Mediates Host Cell Lytic Exit of Chlamydia trachomatis. Front Cell Infect Microbiol 2022; 12:902210. [PMID: 35903198 PMCID: PMC9318579 DOI: 10.3389/fcimb.2022.902210] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 05/25/2022] [Indexed: 11/17/2022] Open
Abstract
Chlamydia trachomatis is an obligate intracellular bacterium causing ocular and urogenital infections in humans that are a significant burden worldwide. The completion of its characteristic infectious cycle relies on the manipulation of several host cell processes by numerous chlamydial type III secretion effector proteins. We previously identified the C. trachomatis CteG effector and showed it localizes at the host cell plasma membrane at late stages of infection. Here, we showed that, from 48 h post-infection, mammalian cells infected by wild-type C. trachomatis contained more infectious chlamydiae in the culture supernatant than cells infected by a CteG-deficient strain. This phenotype was CteG-dependent as it could be complemented in cells infected by the CteG-deficient strain carrying a plasmid encoding CteG. Furthermore, we detected a CteG-dependent defect on host cell cytotoxicity, indicating that CteG mediates chlamydial lytic exit. Previous studies showed that Pgp4, a global regulator of transcription encoded in the C. trachomatis virulence plasmid, also mediates chlamydial lytic exit. However, by using C. trachomatis strains encoding or lacking Pgp4, we showed that production and localization of CteG are not regulated by Pgp4. A C. trachomatis strain lacking both CteG and Pgp4 was as defective in promoting host cell cytotoxicity as mutant strains lacking only CteG or Pgp4. Furthermore, CteG overproduction in a plasmid suppressed the host cell cytotoxic defect of CteG- and Pgp4-deficient chlamydiae. Overall, we revealed the first chlamydial type III secretion effector involved in host cell lytic exit. Our data indicates that CteG and Pgp4 participate in a single cascade of events, but involving multiple layers of regulation, leading to lysis of host cells and release of the infectious chlamydiae.
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Affiliation(s)
- Inês Serrano Pereira
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
- UCIBIO – Applied Molecular Biosciences Unit, Department of Life Sciences, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
| | - Sara Vilela Pais
- UCIBIO – Applied Molecular Biosciences Unit, Department of Life Sciences, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
| | - Vítor Borges
- Bioinformatics Unit, Department of Infectious Diseases, National Institute of Health Dr. Ricardo Jorge (INSA), Lisbon, Portugal
| | - Maria José Borrego
- Bioinformatics Unit, Department of Infectious Diseases, National Institute of Health Dr. Ricardo Jorge (INSA), Lisbon, Portugal
| | - João Paulo Gomes
- Bioinformatics Unit, Department of Infectious Diseases, National Institute of Health Dr. Ricardo Jorge (INSA), Lisbon, Portugal
| | - Luís Jaime Mota
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
- UCIBIO – Applied Molecular Biosciences Unit, Department of Life Sciences, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
- *Correspondence: Luís Jaime Mota,
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Vaccine Design and Vaccination Strategies against Rickettsiae. Vaccines (Basel) 2021; 9:vaccines9080896. [PMID: 34452021 PMCID: PMC8402588 DOI: 10.3390/vaccines9080896] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/10/2021] [Accepted: 08/11/2021] [Indexed: 12/30/2022] Open
Abstract
Rickettsioses are febrile, potentially lethal infectious diseases that are a serious health threat, especially in poor income countries. The causative agents are small obligate intracellular bacteria, rickettsiae. Rickettsial infections are emerging worldwide with increasing incidence and geographic distribution. Nonetheless, these infections are clearly underdiagnosed because methods of diagnosis are still limited and often not available. Another problem is that the bacteria respond to only a few antibiotics, so delayed or wrong antibiotic treatment often leads to a more severe outcome of the disease. In addition to that, the development of antibiotic resistance is a serious threat because alternative antibiotics are missing. For these reasons, prophylactic vaccines against rickettsiae are urgently needed. In the past years, knowledge about protective immunity against rickettsiae and immunogenic determinants has been increasing and provides a basis for vaccine development against these bacterial pathogens. This review provides an overview of experimental vaccination approaches against rickettsial infections and perspectives on vaccination strategies.
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Comparison of Lethal and Nonlethal Mouse Models of Orientia tsutsugamushi Infection Reveals T-Cell Population-Associated Cytokine Signatures Correlated with Lethality and Protection. Trop Med Infect Dis 2021; 6:tropicalmed6030121. [PMID: 34287349 PMCID: PMC8293330 DOI: 10.3390/tropicalmed6030121] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/25/2021] [Accepted: 06/30/2021] [Indexed: 11/19/2022] Open
Abstract
The antigenic diversity of Orientia tsutsugamushi as well as the interstrain difference(s) associated with virulence in mice impose the necessity to dissect the host immune response. In this study we compared the host response in lethal and non-lethal murine models of O. tsutsugamushi infection using the two strains, Karp (New Guinea) and Woods (Australia). The models included the lethal model: Karp intraperitoneal (IP) challenge; and the nonlethal models: Karp intradermal (ID), Woods IP, and Woods ID challenges. We monitored bacterial trafficking to the liver, lung, spleen, kidney, heart, and blood, and seroconversion during the 21-day challenge. Bacterial trafficking to all organs was observed in both the lethal and nonlethal models of infection, with significant increases in average bacterial loads observed in the livers and hearts of the lethal model. Multicolor flow cytometry was utilized to analyze the CD4+ and CD8+ T cell populations and their intracellular production of the cytokines IFNγ, TNF, and IL2 (single, double, and triple combinations) associated with both the lethal and nonlethal murine models of infection. The lethal model was defined by a cytokine signature of double- (IFNγ-IL2) and triple-producing (IL2-TNF-IFNγ) CD4+ T-cell populations; no multifunctional signature was identified in the CD8+ T-cell populations associated with the lethal model. In the nonlethal model, the cytokine signature was predominated by CD4+ and CD8+ T-cell populations associated with single (IL2) and/or double (IL2-TNF) populations of producers. The cytokine signatures associated with our lethal model will become depletion targets in future experiments; those signatures associated with our nonlethal model are hypothesized to be related to the protective nature of the nonlethal challenges.
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Musa TH, Ahmad T, Wana MN, Li W, Musa HH, Sharun K, Tiwari R, Dhama K, Chaicumpa W, Campbell MC, Wei P. The epidemiology, diagnosis and management of scrub typhus disease in China. Hum Vaccin Immunother 2021; 17:3795-3805. [PMID: 34124995 DOI: 10.1080/21645515.2021.1934355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Thirty-nine years ago, scrub typhus (ST), a disease, was not among the China's notifiable diseases. However, ST has reemerged to become a growing public health issue in the southwest part of China. The major factors contributing to an increased incidence and prevalence of this disease include rapid globalization, urbanization, expansion of humans into previously uninhabited areas, and climate change. The clinical manifestation of ST also consists of high fever, headache, weakness, myalgia, rash, and an eschar. In severe cases, complications (e.g. multi-organ failure, jaundice, acute renal failure, pneumonitis, myocarditis, and even death) can occur. The diagnosis of ST is mainly based on serological identification by indirect immunofluorescence assay and other molecular methods. Furthermore, several groups of antibiotics (e.g. tetracycline, chloramphenicol, macrolides, and rifampicin) are currently effective in treating this disease. This fact suggests the need for robust early diagnostic techniques, increased surveillance, and prompt treatment, and develop future vaccine.
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Affiliation(s)
- Taha Hussein Musa
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, Department of Epidemiology and Health Statistics, School of Public Health, Southeast University, Nanjing, China.,Biomedical Research Institute (BRI), Darfur College, Nyala, Sudan
| | - Tauseef Ahmad
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, Department of Epidemiology and Health Statistics, School of Public Health, Southeast University, Nanjing, China
| | - Mohammed Nasiru Wana
- Department of Biological Sciences, Faculty of Science, Abubakar Tafawa Balewa University, Bauchi, Nigeria
| | - Wei Li
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, Department of Epidemiology and Health Statistics, School of Public Health, Southeast University, Nanjing, China
| | - Hassan Hussein Musa
- Faculty of Medical Laboratory Sciences, University of Khartoum, Khartoum, Sudan
| | - Khan Sharun
- Division of Surgery, ICAR-Indian Veterinary Research Institute, Bareilly, India
| | - Ruchi Tiwari
- Department of Veterinary Microbiology and Immunology, College of Veterinary Sciences, UP Deen Dayal Upadhayaya Pashu Chikitsa Vigyan Vishwavidyalay Evum Go-Anusandhan Sansthan (DUVASU), Mathura, India
| | - Kuldeep Dhama
- Division of Pathology, ICAR-Indian Veterinary Research Institute, Bareilly, India
| | - Wanpen Chaicumpa
- Center of Research Excellence on Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | | | - Pingmin Wei
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, Department of Epidemiology and Health Statistics, School of Public Health, Southeast University, Nanjing, China
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8
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Salje J. Cells within cells: Rickettsiales and the obligate intracellular bacterial lifestyle. Nat Rev Microbiol 2021; 19:375-390. [PMID: 33564174 DOI: 10.1038/s41579-020-00507-2] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2020] [Indexed: 01/01/2023]
Abstract
The Rickettsiales are a group of obligate intracellular vector-borne Gram-negative bacteria that include many organisms of clinical and agricultural importance, including Anaplasma spp., Ehrlichia chaffeensis, Wolbachia, Rickettsia spp. and Orientia tsutsugamushi. This Review provides an overview of the current state of knowledge of the biology of these bacteria and their interactions with host cells, with a focus on pathogenic species or those that are otherwise important for human health. This includes a description of rickettsial genomics, bacterial cell biology, the intracellular lifestyles of Rickettsiales and the mechanisms by which they induce and evade the innate immune response.
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Affiliation(s)
- Jeanne Salje
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK. .,Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. .,Public Health Research Institute, Rutgers University, Newark, NJ, USA.
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9
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Abstract
Over the last decades, rickettsioses are emerging worldwide. These diseases are caused by intracellular bacteria. Although rickettsioses can be treated with antibiotics, a vaccine against rickettsiae is highly desired for several reasons. Rickettsioses are highly prevalent, especially in poor countries, and there are indications of the development of antibiotic resistance. In addition, some rickettsiae can persist and cause recurrent disease. The development of a vaccine requires the understanding of the immune mechanisms that are involved in protection as well as in immunopathology. Knowledge about these immune responses is accumulating, and efforts have been undertaken to identify antigenic components of rickettsiae that may be useful as a vaccine. This review provides an overview on current knowledge of adaptive immunity against rickettsiae, which is essential for defense, rickettsial antigens that have been identified so far, and on vaccination strategies that have been used in animal models of rickettsial infections.
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Heydari S, Siavoshi F, Jazayeri MH, Sarrafnejad A, Saniee P. Helicobacter pylori release from yeast as a vesicle-encased or free bacterium. Helicobacter 2020; 25:e12725. [PMID: 32666589 DOI: 10.1111/hel.12725] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 06/22/2020] [Accepted: 06/23/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND Yeast has been suggested as a potent reservoir of H. pylori that facilitates bacterial spread within human populations. What mechanism ensures effective H. pylori release from yeast? Here, H. pylori release from yeast as a vesicle-encased or free bacterium was studied. MATERIALS AND METHODS Liquid culture of Candida yeast was examined by light, fluorescence and transmission electron microscopy methods to observe the released vesicles. Vesicles were isolated and examined by TEM. Immunogold labeling was used for detection of H. pylori-specific proteins in vesicles' membrane. Free bacterial cells, released from yeast, were separated by immunomagnetic separation and observed by field emission scanning electron microscopy (FESEM). DNA of bead-bound bacteria was used for amplification of H. pylori-16S rDNA. Viability of bead-bound bacteria was examined by live/dead stain and cultivation on Brucella blood agar. RESULTS Microscopic observations showed that vesicles contained bacterium-like structures. Thin sections showed release of vesicle-encased or free bacterium from yeast. Immunogold labeling revealed occurrence of H. pylori proteins in vesicles' membrane. FESEM showed attachment of H. pylori cells to magnetic beads. Sequencing of 521 bp PCR product confirmed the identity of bead-bound H. pylori. Live/dead staining showed viability of bead-bound H. pylori but the result of culture was negative. CONCLUSIONS Escape of intracellular H. pylori from yeast as a membrane-bound or free bacterium indicates that H. pylori uses safe exit mechanisms that do not damage the host which is the principle of symbiotic associations. In human stomach, certain conditions may stimulate yeast cells to release H. pylori as a vesicle-encased or free bacterium.
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Affiliation(s)
- Samira Heydari
- Department of Microbiology, School of Biology, University College of Sciences, University of Tehran, Tehran, Iran
| | - Farideh Siavoshi
- Department of Microbiology, School of Biology, University College of Sciences, University of Tehran, Tehran, Iran
| | - Mir Hadi Jazayeri
- Department of Immunology, Faculty of Medical Sciences, Iran University of Medical Sciences, Tehran, Iran.,Immunology Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Abdolfattah Sarrafnejad
- Department of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Parastoo Saniee
- Department of Microbiology and Microbial Biotechnology, Faculty of Life Science and Biotechnology, Shahid Beheshti University, Tehran, Iran
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Alsultan M, Morriss J, Contaifer D, Kumar NG, Wijesinghe DS. Host Lipid Response in Tropical Diseases. CURRENT TREATMENT OPTIONS IN INFECTIOUS DISEASES 2020. [DOI: 10.1007/s40506-020-00222-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Lipid Droplets: A Significant but Understudied Contributor of Host⁻Bacterial Interactions. Cells 2019; 8:cells8040354. [PMID: 30991653 PMCID: PMC6523240 DOI: 10.3390/cells8040354] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 04/05/2019] [Accepted: 04/12/2019] [Indexed: 12/13/2022] Open
Abstract
Lipid droplets (LDs) are cytosolic lipid storage organelles that are important for cellular lipid metabolism, energy homeostasis, cell signaling, and inflammation. Several bacterial, viral and protozoal pathogens exploit host LDs to promote infection, thus emphasizing the importance of LDs at the host–pathogen interface. In this review, we discuss the thus far reported relation between host LDs and bacterial pathogens including obligate and facultative intracellular bacteria, and extracellular bacteria. Although there is less evidence for a LD–extracellular bacterial interaction compared to interactions with intracellular bacteria, in this review, we attempt to compare the bacterial mechanisms that target LDs, the host signaling pathways involved and the utilization of LDs by these bacteria. Many intracellular bacteria employ unique mechanisms to target host LDs and potentially obtain nutrients and lipids for vacuolar biogenesis and/or immune evasion. However, extracellular bacteria utilize LDs to either promote host tissue damage or induce host death. We also identify several areas that require further investigation. Along with identifying LD interactions with bacteria besides the ones reported, the precise mechanisms of LD targeting and how LDs benefit pathogens should be explored for the bacteria discussed in the review. Elucidating LD–bacterial interactions promises critical insight into a novel host–pathogen interaction.
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Soong L. Dysregulated Th1 Immune and Vascular Responses in Scrub Typhus Pathogenesis. THE JOURNAL OF IMMUNOLOGY 2019; 200:1233-1240. [PMID: 29431689 DOI: 10.4049/jimmunol.1701219] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 11/30/2017] [Indexed: 12/25/2022]
Abstract
Scrub typhus is an emerging, insect-transmitted disease caused by Orientia tsutsugamushi, a Gram- and LPS-negative bacterium that replicates freely within professional phagocytes and endothelial cells. Scrub typhus is prevalent with high mortality rates, but information regarding its molecular pathogenesis, microbial virulence determinants, and key immune responses is limited. Improved animal models have recently been developed that respectively resemble the pathological features of self-limiting or severe scrub typhus in humans. Strong activation of Th1 and CD8, but not Th2 and regulatory T, immune responses, accompanied by altered angiopoietin/Tie2-related regulation, are hallmarks of lethal infection in murine models. This review, based primarily on recent advances from clinical and experimental studies, highlights tissue- and endothelial cell-specific biomarkers that are indicative of immune dysregulation. The potential roles of neutrophils and damage-associated molecular pattern molecules at late stages of disease are discussed in the context of vascular leakage, pulmonary and renal injury, and scrub typhus pathogenesis.
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Affiliation(s)
- Lynn Soong
- Department of Microbiology and Immunology, Center for Tropical Diseases, Center for Biodefense and Emerging Infectious Diseases, Sealy Center for Vaccine Development, Institute of Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555; and .,Department of Pathology, Center for Tropical Diseases, Center for Biodefense and Emerging Infectious Diseases, Sealy Center for Vaccine Development, Institute of Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555
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14
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Lalchhandama K. Orientia tsutsugamushi, the agent of scrub typhus. WIKIJOURNAL OF MEDICINE 2019. [DOI: 10.15347/wjm/2019.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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15
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Flieger A, Frischknecht F, Häcker G, Hornef MW, Pradel G. Pathways of host cell exit by intracellular pathogens. MICROBIAL CELL 2018; 5:525-544. [PMID: 30533418 PMCID: PMC6282021 DOI: 10.15698/mic2018.12.659] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Host cell exit is a critical step in the life-cycle of intracellular pathogens, intimately linked to barrier penetration, tissue dissemination, inflammation, and pathogen transmission. Like cell invasion and intracellular survival, host cell exit represents a well-regulated program that has evolved during host-pathogen co-evolution and that relies on the dynamic and intricate interplay between multiple host and microbial factors. Three distinct pathways of host cell exit have been identified that are employed by three different taxa of intracellular pathogens, bacteria, fungi and protozoa, namely (i) the initiation of programmed cell death, (ii) the active breaching of host cellderived membranes, and (iii) the induced membrane-dependent exit without host cell lysis. Strikingly, an increasing number of studies show that the majority of intracellular pathogens utilize more than one of these strategies, dependent on life-cycle stage, environmental factors and/or host cell type. This review summarizes the diverse exit strategies of intracellular-living bacterial, fungal and protozoan pathogens and discusses the convergently evolved commonalities as well as system-specific variations thereof. Key microbial molecules involved in host cell exit are highlighted and discussed as potential targets for future interventional approaches.
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Affiliation(s)
- Antje Flieger
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Wernigerode, Germany
| | | | - Georg Häcker
- Institute of Medical Microbiology and Hygiene, Medical Center - University of Freiburg, Germany
| | - Mathias W Hornef
- Institute of Medical Microbiology, RWTH Aachen University Hospital, Germany
| | - Gabriele Pradel
- Division of Cellular and Applied Infection Biology, Institute of Biology II, RWTH Aachen University, Germany
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16
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Díaz FE, Abarca K, Kalergis AM. An Update on Host-Pathogen Interplay and Modulation of Immune Responses during Orientia tsutsugamushi Infection. Clin Microbiol Rev 2018; 31:e00076-17. [PMID: 29386235 PMCID: PMC5967693 DOI: 10.1128/cmr.00076-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The obligate intracellular bacterium Orientia tsutsugamushi is the causative agent of scrub typhus in humans, a serious mite-borne disease present in a widespread area of endemicity, which affects an estimated 1 million people every year. This disease may exhibit a broad range of presentations, ranging from asymptomatic to fatal conditions, with the latter being due to disseminated endothelial infection and organ injury. Unique characteristics of the biology and host-pathogen interactions of O. tsutsugamushi, including the high antigenic diversity among strains and the highly variable, short-lived memory responses developed by the host, underlie difficulties faced in the pursuit of an effective vaccine, which is an imperative need. Other factors that have hindered scientific progress relative to the infectious mechanisms of and the immune response triggered by this bacterium in vertebrate hosts include the limited number of mechanistic studies performed on animal models and the lack of genetic tools currently available for this pathogen. However, recent advances in animal model development are promising to improve our understanding of host-pathogen interactions. Here, we comprehensively discuss the recent advances in and future perspectives on host-pathogen interactions and the modulation of immune responses related to this reemerging disease, highlighting the role of animal models.
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Affiliation(s)
- Fabián E Díaz
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Katia Abarca
- Departamento en Enfermedades Infecciosas e Inmunología Pediátricas, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alexis M Kalergis
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Departamento de Endocrinología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
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Abstract
The coevolution of intracellular bacteria with their eukaryotic hosts has presented these pathogens with numerous challenges for their evolutionary progress and survival. Chief among these is the ability to exit from host cells, an event that is fundamentally linked to pathogen dissemination and transmission. Recent years have witnessed a major expansion of research in this area, and this chapter summarizes our current understanding of the spectrum of exit strategies that are exploited by intracellular pathogens. Clear themes regarding the mechanisms of microbial exit have emerged and are most easily conceptualized as (i) lysis of the host cell, (ii) nonlytic exit of free bacteria, and (iii) release of microorganisms into membrane-encased compartments. The adaptation of particular exit strategies is closely linked with additional themes in microbial pathogenesis, including host cell death, manipulation of host signaling pathways, and coincident activation of proinflammatory responses. This chapter will explore the molecular determinants used by intracellular pathogens to promote host cell escape and the infectious advantages each exit pathway may confer, and it will provide an evolutionary framework for the adaptation of these mechanisms.
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18
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Affiliation(s)
- Jeanne Salje
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- * E-mail:
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Osterloh A. Immune response against rickettsiae: lessons from murine infection models. Med Microbiol Immunol 2017; 206:403-417. [PMID: 28770333 PMCID: PMC5664416 DOI: 10.1007/s00430-017-0514-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Accepted: 07/20/2017] [Indexed: 12/19/2022]
Abstract
Rickettsiae are small intracellular bacteria that can cause life-threatening febrile diseases. Rickettsioses occur worldwide with increasing incidence. Therefore, a vaccine is highly desired. A prerequisite for the development of a vaccine is the knowledge of the immune response against these bacteria, in particular protective immunity. In recent years murine models of rickettsial infections have been established, and the study of immune response against rickettsiae in mice provided many new insights into protective and pathological immune reactions. This review summarizes the current knowledge about immune mechanisms in protection and pathology in rickettsial infections.
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Affiliation(s)
- Anke Osterloh
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
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20
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Samanta D, Mulye M, Clemente TM, Justis AV, Gilk SD. Manipulation of Host Cholesterol by Obligate Intracellular Bacteria. Front Cell Infect Microbiol 2017; 7:165. [PMID: 28529926 PMCID: PMC5418226 DOI: 10.3389/fcimb.2017.00165] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 04/18/2017] [Indexed: 12/29/2022] Open
Abstract
Cholesterol is a multifunctional lipid that plays important metabolic and structural roles in the eukaryotic cell. Despite having diverse lifestyles, the obligate intracellular bacterial pathogens Chlamydia, Coxiella, Anaplasma, Ehrlichia, and Rickettsia all target cholesterol during host cell colonization as a potential source of membrane, as well as a means to manipulate host cell signaling and trafficking. To promote host cell entry, these pathogens utilize cholesterol-rich microdomains known as lipid rafts, which serve as organizational and functional platforms for host signaling pathways involved in phagocytosis. Once a pathogen gains entrance to the intracellular space, it can manipulate host cholesterol trafficking pathways to access nutrient-rich vesicles or acquire membrane components for the bacteria or bacteria-containing vacuole. To acquire cholesterol, these pathogens specifically target host cholesterol metabolism, uptake, efflux, and storage. In this review, we examine the strategies obligate intracellular bacterial pathogens employ to manipulate cholesterol during host cell colonization. Understanding how obligate intracellular pathogens target and use host cholesterol provides critical insight into the host-pathogen relationship.
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Affiliation(s)
- Dhritiman Samanta
- Department of Microbiology and Immunology, Indiana University School of MedicineIndianapolis, IN, USA
| | - Minal Mulye
- Department of Microbiology and Immunology, Indiana University School of MedicineIndianapolis, IN, USA
| | - Tatiana M Clemente
- Department of Microbiology and Immunology, Indiana University School of MedicineIndianapolis, IN, USA
| | - Anna V Justis
- Department of Microbiology and Immunology, Indiana University School of MedicineIndianapolis, IN, USA
| | - Stacey D Gilk
- Department of Microbiology and Immunology, Indiana University School of MedicineIndianapolis, IN, USA
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21
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Exploitation of host lipids by bacteria. Curr Opin Microbiol 2013; 17:38-45. [PMID: 24581691 DOI: 10.1016/j.mib.2013.11.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 10/27/2013] [Accepted: 11/09/2013] [Indexed: 11/21/2022]
Abstract
Bacteria that interact with eukaryotic cells have developed a variety of strategies to divert host lipids, or cellular processes driven by lipids, to their benefit. Host lipids serve as building blocks for bacterial membrane formation and as energy source. They promote the formation of specific microdomains, facilitating interactions with the host. Host lipids are also critical players in the entry of bacteria or toxins into cells, and, for bacteria growing inside parasitophorous vacuoles, in building a secure shelter. Bacterial dissemination is often dependent on enzymatic activities targeting host lipids. Finally, on a larger scale, long lasting parasitic association can disturb host lipid metabolism so deeply as to 'reprogram' it, as proposed in the case of Mycobacterium infection.
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