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Khakhum N, Baruch-Torres N, Stockton JL, Chapartegui-González I, Badten AJ, Adam A, Wang T, Huerta-Saquero A, Yin YW, Torres AG. Decoration of Burkholderia Hcp1 protein to virus-like particles as a vaccine delivery platform. Infect Immun 2024; 92:e0001924. [PMID: 38353543 PMCID: PMC10929448 DOI: 10.1128/iai.00019-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 01/23/2024] [Indexed: 03/13/2024] Open
Abstract
Virus-like particles (VLPs) are protein-based nanoparticles frequently used as carriers in conjugate vaccine platforms. VLPs have been used to display foreign antigens for vaccination and to deliver immunotherapy against diseases. Hemolysin-coregulated proteins 1 (Hcp1) is a protein component of the Burkholderia type 6 secretion system, which participates in intracellular invasion and dissemination. This protein has been reported as a protective antigen and is used in multiple vaccine candidates with various platforms against melioidosis, a severe infectious disease caused by the intracellular pathogen Burkholderia pseudomallei. In this study, we used P22 VLPs as a surface platform for decoration with Hcp1 using chemical conjugation. C57BL/6 mice were intranasally immunized with three doses of either PBS, VLPs, or conjugated Hcp1-VLPs. Immunization with Hcp1-VLPs formulation induced Hcp1-specific IgG, IgG1, IgG2c, and IgA antibody responses. Furthermore, the serum from Hcp1-VLPs immunized mice enhanced the bacterial uptake and opsonophagocytosis by macrophages in the presence of complement. This study demonstrated an alternative strategy to develop a VLPs-based vaccine platform against Burkholderia species.
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Affiliation(s)
- Nittaya Khakhum
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Noe Baruch-Torres
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, Galveston, Texas, USA
| | - Jacob L. Stockton
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | | | - Alexander J. Badten
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, USA
- Institute for Translational Sciences, Galveston, Texas, USA
| | - Awadalkareem Adam
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Tian Wang
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Alejandro Huerta-Saquero
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, USA
- Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Ensenada, Baja California, Mexico
| | - Y. Whitney Yin
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, Galveston, Texas, USA
| | - Alfredo G. Torres
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, USA
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
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Meumann EM, Limmathurotsakul D, Dunachie SJ, Wiersinga WJ, Currie BJ. Burkholderia pseudomallei and melioidosis. Nat Rev Microbiol 2024; 22:155-169. [PMID: 37794173 DOI: 10.1038/s41579-023-00972-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/04/2023] [Indexed: 10/06/2023]
Abstract
Burkholderia pseudomallei, the causative agent of melioidosis, is found in soil and water of tropical and subtropical regions globally. Modelled estimates of the global burden predict that melioidosis remains vastly under-reported, and a call has been made for it to be recognized as a neglected tropical disease by the World Health Organization. Severe weather events and environmental disturbance are associated with increased case numbers, and it is anticipated that, in some regions, cases will increase in association with climate change. Genomic epidemiological investigations have confirmed B. pseudomallei endemicity in newly recognized regions, including the southern United States. Melioidosis follows environmental exposure to B. pseudomallei and is associated with comorbidities that affect the immune response, such as diabetes, and with socioeconomic disadvantage. Several vaccine candidates are ready for phase I clinical trials. In this Review, we explore the global burden, epidemiology and pathophysiology of B. pseudomallei as well as current diagnostics, treatment recommendations and preventive measures, highlighting research needs and priorities.
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Affiliation(s)
- Ella M Meumann
- Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia.
- Department of Infectious Diseases, Division of Medicine, Royal Darwin Hospital, Darwin, Northern Territory, Australia.
| | - Direk Limmathurotsakul
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
- Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- NDM Centre for Global Health Research, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Susanna J Dunachie
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
- NDM Centre for Global Health Research, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Willem J Wiersinga
- Division of Infectious Diseases, Center for Experimental Molecular Medicine, Amsterdam University Medical Centers, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands
| | - Bart J Currie
- Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia
- Department of Infectious Diseases, Division of Medicine, Royal Darwin Hospital, Darwin, Northern Territory, Australia
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Herron ICT, Laws TR, Nelson M. Marmosets as models of infectious diseases. Front Cell Infect Microbiol 2024; 14:1340017. [PMID: 38465237 PMCID: PMC10921895 DOI: 10.3389/fcimb.2024.1340017] [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: 11/17/2023] [Accepted: 01/29/2024] [Indexed: 03/12/2024] Open
Abstract
Animal models of infectious disease often serve a crucial purpose in obtaining licensure of therapeutics and medical countermeasures, particularly in situations where human trials are not feasible, i.e., for those diseases that occur infrequently in the human population. The common marmoset (Callithrix jacchus), a Neotropical new-world (platyrrhines) non-human primate, has gained increasing attention as an animal model for a number of diseases given its small size, availability and evolutionary proximity to humans. This review aims to (i) discuss the pros and cons of the common marmoset as an animal model by providing a brief snapshot of how marmosets are currently utilized in biomedical research, (ii) summarize and evaluate relevant aspects of the marmoset immune system to the study of infectious diseases, (iii) provide a historical backdrop, outlining the significance of infectious diseases and the importance of developing reliable animal models to test novel therapeutics, and (iv) provide a summary of infectious diseases for which a marmoset model exists, followed by an in-depth discussion of the marmoset models of two studied bacterial infectious diseases (tularemia and melioidosis) and one viral infectious disease (viral hepatitis C).
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Affiliation(s)
- Ian C. T. Herron
- CBR Division, Defence Science and Technology Laboratory (Dstl), Salisbury, United Kingdom
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Stockton JL, Khakhum N, Stevenson HL, Torres AG. Burkholderia pseudomallei BicA protein promotes pathogenicity in macrophages by regulating invasion, intracellular survival, and virulence. mSphere 2023; 8:e0037823. [PMID: 37768049 PMCID: PMC10597401 DOI: 10.1128/msphere.00378-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 08/08/2023] [Indexed: 09/29/2023] Open
Abstract
Burkholderia pseudomallei (Bpm) is the causative agent of melioidosis disease. Bpm is a facultative intracellular pathogen with a complex life cycle inside host cells. Pathogenic success depends on a variety of virulence factors with one of the most critical being the type 6 secretion system (T6SS). Bpm uses the T6SS to move into neighboring cells, resulting in multinucleated giant cell (MNGC) formation, a strategy used to disseminate from cell to cell. Our prior study using a dual RNA-seq analysis to dissect T6SS-mediated virulence on intestinal epithelial cells identified BicA as a factor upregulated in a T6SS mutant. BicA regulates both type 3 secretion system (T3SS) and T6SSs; however, the extent of its involvement during disease progression is unclear. To fully dissect the role of BicA during systemic infection, we used two macrophage cell lines paired with a pulmonary in vivo challenge murine model. We found that ΔbicA has a distinct intracellular replication defect in both immortalized and primary macrophages, which begins as early as 1 h post-infection. This intracellular defect is linked with the lack of cell-to-cell dissemination and MNGC formation as well as a defect in T3SS expression. The in vitro phenotype translated in vivo as ΔbicA was attenuated in a pulmonary model of infection, demonstrating a distinct macrophage activation profile and a lack of pathological features present in the wild type. Overall, these results highlight the role of BicA in regulating intracellular virulence and demonstrate that specific regulation of secretion systems has a significant effect on host response and Bpm pathogenesis. IMPORTANCE Melioidosis is an understudied tropical disease that still results in ~50% fatalities in infected patients. It is caused by the Gram-negative bacillus Burkholderia pseudomallei (Bpm). Bpm is an intracellular pathogen that disseminates from the infected cell to target organs, causing disseminated disease. The regulation of secretion systems involved in entry and cell-to-cell spread is poorly understood. In this work, we characterize the role of BicA as a regulator of secretion systems during infection of macrophages in vitro and in vivo. Understanding how these virulence factors are controlled will help us determine their influence on the host cells and define the macrophage responses associated with bacterial clearance.
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Affiliation(s)
- Jacob L. Stockton
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Nittaya Khakhum
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Heather L. Stevenson
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Alfredo G. Torres
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, USA
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
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Huerta-Saquero A, Chapartegui-González I, Bowser S, Khakhum N, Stockton JL, Torres AG. P22-Based Nanovaccines against Enterohemorrhagic Escherichia coli. Microbiol Spectr 2023:e0473422. [PMID: 36943089 PMCID: PMC10100862 DOI: 10.1128/spectrum.04734-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) is an important causative agent of diarrhea in humans that causes outbreaks worldwide. Efforts have been made to mitigate the morbidity and mortality caused by these microorganisms; however, the global incidence is still high, causing hundreds of deaths per year. Several vaccine candidates have been evaluated that demonstrate some stability and therapeutic potential but have limited overarching effect. Virus-like particles have been used successfully as nanocontainers for the targeted delivery of drugs, proteins, or nucleic acids. In this study, phage P22 nanocontainers were used as a carrier for the highly antigenic T3SS structural protein EscC that is conserved between EHEC and other enteropathogenic bacteria. We were able to stably incorporate the EscC protein into P22 nanocontainers. The EscC-P22 particles were used to intranasally inoculate mice, which generated specific antibodies against EscC. These antibodies increased the phagocytic activity of murine macrophages infected with EHEC in vitro and reduced bacterial adherence to Caco-2 epithelial cells in vitro, illustrating their functionality. The EscC-P22-based particles are a potential nanovaccine candidate for immunization against EHEC O157:H7 infections. IMPORTANCE This study describes the initial attempt to use P22 viral-like particles as nanocontainers expressing enterohemorrhagic Escherichia coli (EHEC) proteins that are immunogenic and could be used as effective vaccines against EHEC infections.
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Affiliation(s)
- Alejandro Huerta-Saquero
- Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Ensenada, Baja California, México
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | | | - Sarah Bowser
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Nittaya Khakhum
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Jacob L Stockton
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Alfredo G Torres
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
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Ali A, Waris A, Khan MA, Asim M, Khan AU, Khan S, Zeb J. Recent advancement, immune responses, and mechanism of action of various vaccines against intracellular bacterial infections. Life Sci 2023; 314:121332. [PMID: 36584914 DOI: 10.1016/j.lfs.2022.121332] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 12/20/2022] [Accepted: 12/23/2022] [Indexed: 12/29/2022]
Abstract
Emerging and re-emerging bacterial infections are a serious threat to human and animal health. Extracellular bacteria are free-living, while facultative intracellular bacteria replicate inside eukaryotic host cells. Many serious human illnesses are now known to be caused by intracellular bacteria such as Salmonella enterica, Escherichia coli, Staphylococcus aureus, Rickettsia massiliae, Chlamydia species, Brucella abortus, Mycobacterium tuberculosis and Listeria monocytogenes, which result in substantial morbidity and mortality. Pathogens like Mycobacterium, Brucella, MRSA, Shigella, Listeria, and Salmonella can infiltrate and persist in mammalian host cells, particularly macrophages, where they proliferate and establish a repository, resulting in chronic and recurrent infections. The current treatment for these bacteria involves the application of narrow-spectrum antibiotics. FDA-approved vaccines against obligate intracellular bacterial infections are lacking. The development of vaccines against intracellular pathogenic bacteria are more difficult because host defense against these bacteria requires the activation of the cell-mediated pathway of the immune system, such as CD8+ T and CD4+ T. However, different types of vaccines, including live, attenuated, subunit, killed whole cell, nano-based and DNA vaccines are currently in clinical trials. Substantial development has been made in various vaccine strategies against intracellular pathogenic bacteria. This review focuses on the mechanism of intracellular bacterial infection, host immune response, and recent advancements in vaccine development strategies against various obligate intracellular bacterial infections.
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Affiliation(s)
- Asmat Ali
- Department of Biotechnology and Genetic Engineering, Hazara University Mansehra, Pakistan
| | - Abdul Waris
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong.
| | - Muhammad Ajmal Khan
- Division of Life Sciences, Center for Cancer Research and State Key Laboratory of Molecular Neurosciences, The Hong Kong University of Science and Technology, Hong Kong
| | - Muhammad Asim
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong
| | - Atta Ullah Khan
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, China
| | - Sahrish Khan
- Department of Biotechnology, Quaid-i-Azam University, Islamabad, Pakistan
| | - Jehan Zeb
- Department of Infectious Diseases and Public Health, City University of Hong Kong, Hong Kong
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Zhu K, Li G, Li J, Zheng M, Peng X, Rao Y, Li M, Zhou R, Rao X. Hcp1-loaded staphylococcal membrane vesicle vaccine protects against acute melioidosis. Front Immunol 2022; 13:1089225. [PMID: 36618368 PMCID: PMC9822774 DOI: 10.3389/fimmu.2022.1089225] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022] Open
Abstract
Burkholderia pseudomallei is the causal agent of melioidosis, a deadly tropical infectious disease that lacks a vaccine. On the basis of the attenuated Staphylococcus aureus RN4220-Δagr (RN), we engineered the RN4220-Δagr/pdhB-hcp1 strain (RN-Hcp1) to generate B. pseudomallei hemolysin-coregulated protein 1 (Hcp1)-loaded membrane vesicles (hcp1MVs). The immunization of BALB/c mice with hcp1MVs mixed with adjuvant by a three-dose regimen increased the serum specific IgG production. The serum levels of inflammatory factors, including TNF-α and IL-6, in hcp1MV-vaccinated mice were comparable with those in PBS-challenged mice. The partial adjuvant effect of staphylococcal MVs was observed with the elevation of specific antibody titer in hcp1MV-vaccinated mice relative to those that received the recombinant Hcp1 protein (rHcp1) or MVs derived from RN strain (ΔagrMVs). The hcp1MVs/adjuvant vaccine protected 70% of mice from lethal B. pseudomallei challenge. Immunization with hcp1MVs only protected 60% of mice, whereas vaccination with rHcp1 or ΔagrMVs conferred no protection. Moreover, mice that received hcp1MVs/adjuvant and hcp1MVs immunization had low serum TNF-α and IL-6 levels and no inflammatory infiltration in comparison with other groups. In addition, all surviving mice in hcp1MVs/adjuvant and hcp1MVs groups exhibited no culturable bacteria in their lungs, livers, and spleens five days postinfection. Overall, our data highlighted a new strategy for developing B. pseudomallei vaccine and showed that Hcp1-incorporated staphylococcal MV is a promising candidate for the prevention of acute melioidosis.
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Affiliation(s)
- Keting Zhu
- Department of Emergency Medicine, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Gang Li
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Jia Li
- Department of Emergency Medicine, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Mingxia Zheng
- Department of Emergency Medicine, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Xiaohui Peng
- Department of Emergency Medicine, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Yifan Rao
- Department of Emergency Medicine, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Ming Li
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University, Chongqing, China,*Correspondence: Ming Li, ; Renjie Zhou, ; Xiancai Rao,
| | - Renjie Zhou
- Department of Emergency Medicine, Xinqiao Hospital, Army Medical University, Chongqing, China,*Correspondence: Ming Li, ; Renjie Zhou, ; Xiancai Rao,
| | - Xiancai Rao
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University, Chongqing, China,*Correspondence: Ming Li, ; Renjie Zhou, ; Xiancai Rao,
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Early Activation of iNKT Cells Increased Survival Time of BALB/c Mice in a Murine Model of Melioidosis. Infect Immun 2022; 90:e0026822. [PMID: 36374098 PMCID: PMC9753712 DOI: 10.1128/iai.00268-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Melioidosis is an infectious disease caused by Burkholderia pseudomallei. High interferon gamma (IFN-γ) levels in naive mice were reported to mediate protection against B. pseudomallei infection. Invariant natural killer T (iNKT) cells can produce and secrete several cytokines, including IFN-γ. When iNKT cell-knockout (KO) BALB/c mice were infected with B. pseudomallei, their survival time was significantly shorter than wild-type mice. Naive BALB/c mice pretreated intraperitoneally with α-galactosylceramide (α-GalCer), an iNKT cell activator, 24 h before infection demonstrated 62.5% survival at the early stage, with prolonged survival time compared to nonpretreated infected control mice (14 ± 1 days versus 6 ± 1 days, respectively). At 4 h after injection with α-GalCer, treated mice showed significantly higher levels of serum IFN-γ, interleukin-4 (IL-4), IL-10, and IL-12 than control mice. Interestingly, the IFN-γ levels in the α-GalCer-pretreated group were decreased at 4, 24, and 48 h after infection, while they were highly increased in the control group. At 24 h postinfection in the α-GalCer group, bacterial loads were significantly lower in blood (no growth and 1,780.00 ± 51.21, P < 0.0001), spleens (no growth and 34,300 ± 1,106.04, P < 0.0001), and livers (1,550 ± 68.72 and 13,400 ± 1,066.67, P < 0.0001) than in the control group, but not in the lungs (15,300 ± 761.10 and 1,320 ± 41.63, P < 0.0001), and almost all were negative at 48 h postinfection. This study for the first time shows that early activation of iNKT cells by α-GalCer helps clearance of B. pseudomallei and prolongs mouse survival.
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Functional Activities of O-Polysaccharide and Hemolysin Coregulated Protein 1 Specific Antibodies Isolated from Melioidosis Patients. Infect Immun 2022; 90:e0021422. [PMID: 36226942 PMCID: PMC9670879 DOI: 10.1128/iai.00214-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Melioidosis is a fatal tropical disease caused by the environmental Gram-negative bacterium, Burkholderia pseudomallei. This bacterium is intrinsically resistant to several antibiotics and treatment of melioidosis requires prolonged antibiotic administration. To date, there are no vaccines available for melioidosis. Previous studies have shown that humoral immunity is critical for surviving melioidosis and that O-polysaccharide (OPS) and hemolysin coregulated protein 1 (Hcp1) are important protective antigens in animal models of melioidosis. Our previous studies revealed that melioidosis patients had high levels of OPS- and Hcp1-specific antibodies and that IgG against OPS (IgG-OPS) and Hcp1 (IgG-Hcp1) were associated with patient survival. In this study, we characterized the potential function(s) of IgG-OPS and IgG-Hcp1 from melioidosis patients. IgG-OPS and IgG-Hcp1 were purified from pooled serum obtained from melioidosis patients using immuno-affinity chromatography. Antibody-dependent cellular phagocytosis assays were performed with pooled serum from melioidosis patients and compared with serum obtained from healthy controls. Serum from melioidosis patients significantly enhanced B. pseudomallei uptake into the human monocytic cell line THP-1 compared with pooled serum from healthy donors. Enhanced opsonization was observed with IgG-OPS and IgG-Hcp1 in a dose-dependent manner. Antibody-dependent complement deposition assays were performed with IgG-OPS and IgG-Hcp1 using flow cytometry and showed that there was enhanced C3b deposition on the surface of B. pseudomallei treated with IgG-OPS but to a lesser degree with IgG-Hcp1. This study provides insight into the function of IgG-OPS and IgG-Hcp1 in human melioidosis and supports that OPS and Hcp1 are potential vaccine antigens for immunization against melioidosis.
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Efficacy of Co-Trimoxazole against Experimental Melioidosis Acquired by Different Routes of Infection. Antimicrob Agents Chemother 2022; 66:e0070822. [PMID: 36226972 DOI: 10.1128/aac.00708-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Burkholderia pseudomallei is the causative agent of melioidosis and presents with diverse clinical manifestations. Naturally occurring infection occurs following contamination of cuts or skin abrasions, or ingestion of contaminated water, and occasionally through inhalational of infected soil or water particles. The influence of the route of disease acquisition on the efficacy of medical countermeasures has not been explored in humans or in appropriate animal models. The efficacy of co-trimoxazole against melioidosis acquired by different routes of exposure was assessed in postexposure prophylaxis (PEP) and treatment studies in marmoset models of melioidosis. Following challenge with B. pseudomallei by the inhalational, subcutaneous, or ingestion routes of administration, animals were given co-trimoxazole at 12 hourly intervals for 14 days, starting either 6 h postchallenge or at the onset of fever. Animals were then observed for 28 days. All animals that received antibiotic 6 h postchallenge survived the duration of dosing. All animals that received antibiotics at the onset of fever completed the treatment, but 10%, 57%, and 60% of those with ingestion, subcutaneous, and inhalation challenge relapsed, respectively. Bacteriological and histological differences were observed between placebo-control animals and those that relapsed. Immunological profiles indicate difference between animals given placebo and those that relapsed or survived the duration of the study. A broad T-cell activation was observed in animals that survived. Overall, these data suggest the efficacy of co-trimoxazole, as measured in the incidence of relapse, differs depending on the disease-acquisition route. Therefore, there are implications in treating this disease in regions of endemicity.
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Biryukov SS, Cote CK, Klimko CP, Dankmeyer JL, Rill NO, Shoe JL, Hunter M, Shamsuddin Z, Velez I, Hedrick ZM, Rosario-Acevedo R, Talyansky Y, Schmidt LK, Orne CE, Fetterer DP, Burtnick MN, Brett PJ, Welkos SL, DeShazer D. Evaluation of two different vaccine platforms for immunization against melioidosis and glanders. Front Microbiol 2022; 13:965518. [PMID: 36060742 PMCID: PMC9428723 DOI: 10.3389/fmicb.2022.965518] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 07/22/2022] [Indexed: 11/13/2022] Open
Abstract
Burkholderia pseudomallei and the closely related species, Burkholderia mallei, produce similar multifaceted diseases which range from rapidly fatal to protracted and chronic, and are a major cause of mortality in endemic regions. Besides causing natural infections, both microbes are Tier 1 potential biothreat agents. Antibiotic treatment is prolonged with variable results, hence effective vaccines are urgently needed. The purpose of our studies was to compare candidate vaccines that target both melioidosis and glanders to identify the most efficacious one(s) and define residual requirements for their transition to the non-human primate aerosol model. Studies were conducted in the C57BL/6 mouse model to evaluate the humoral and cell-mediated immune response and protective efficacy of three Burkholderia vaccine candidates against lethal aerosol challenges with B. pseudomallei K96243, B. pseudomallei MSHR5855, and B. mallei FMH. The recombinant vaccines generated significant immune responses to the vaccine antigens, and the live attenuated vaccine generated a greater immune response to OPS and the whole bacterial cells. Regardless of the candidate vaccine evaluated, the protection of mice was associated with a dampened cytokine response within the lungs after exposure to aerosolized bacteria. Despite being delivered by two different platforms and generating distinct immune responses, two experimental vaccines, a capsule conjugate + Hcp1 subunit vaccine and the live B. pseudomallei 668 ΔilvI strain, provided significant protection and were down-selected for further investigation and advanced development.
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Affiliation(s)
- Sergei S. Biryukov
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Christopher K. Cote
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
- *Correspondence: Christopher K. Cote
| | - Christopher P. Klimko
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Jennifer L. Dankmeyer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Nathaniel O. Rill
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Jennifer L. Shoe
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Melissa Hunter
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Zain Shamsuddin
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Ivan Velez
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Zander M. Hedrick
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Raysa Rosario-Acevedo
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Yuli Talyansky
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Lindsey K. Schmidt
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, NV, United States
| | - Caitlyn E. Orne
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, NV, United States
| | - David P. Fetterer
- Biostatistics Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Mary N. Burtnick
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, NV, United States
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Paul J. Brett
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, NV, United States
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Susan L. Welkos
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - David DeShazer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
- David DeShazer
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12
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Development of Melioidosis Subunit Vaccines Using an Enzymatically Inactive Burkholderia pseudomallei AhpC. Infect Immun 2022; 90:e0022222. [PMID: 35862715 PMCID: PMC9387246 DOI: 10.1128/iai.00222-22] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Burkholderia pseudomallei, the causative agent of melioidosis, is a facultative intracellular, Gram-negative pathogen that is highly infectious via the respiratory route and can cause severe, debilitating, and often fatal diseases in humans and animals. At present, no licensed vaccines for immunization against this CDC Tier 1 select agent exist. Studies in our lab have previously demonstrated that subunit vaccine formulations consisting of a B. pseudomallei capsular polysaccharide (CPS)-based glycoconjugate (CPS-CRM197) combined with hemolysin-coregulated protein (Hcp1) provided C57BL/6 mice with high-level protection against an acute inhalational challenge of B. pseudomallei. In this study, we evaluated the immunogenicity and protective capacity of B. pseudomallei alkyl hydroperoxide reductase subunit C (AhpC) in combination with CPS-CRM197. AhpC is a peroxiredoxin involved in oxidative stress reduction and is a potential protective antigen. To facilitate our studies and maximize safety in animals, recombinant B. pseudomallei AhpC harboring an active site mutation (AhpCC57G) was expressed in Escherichia coli and purified using tandem nickel-cobalt affinity chromatography. Immunization of C57BL/6 mice with CPS-CRM197 combined with AhpCC57G stimulated high-titer IgG responses against the CPS component of the glycoconjugate as well as stimulated high-titer IgG and robust interferon gamma (IFN-γ)-, interleukin-5 (IL-5)-, and IL-17-secreting T cell responses against AhpCC57G. When challenged via an inhalational route with a high dose (~27 50% lethal doses [LD50s]) of B. pseudomallei, 70% of the immunized mice survived 35 days postchallenge. Collectively, our findings demonstrate that AhpCC57G is a potent activator of cellular and humoral immune responses and may be a promising candidate to include in future melioidosis subunit vaccines.
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13
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Sanchez-Villamil JI, Tapia D, Khakhum N, Widen SG, Torres AG. Dual RNA-seq reveals a type 6 secretion system-dependent blockage of TNF-α signaling and BicA as a Burkholderia pseudomallei virulence factor important during gastrointestinal infection. Gut Microbes 2022; 14:2111950. [PMID: 35984745 PMCID: PMC9397134 DOI: 10.1080/19490976.2022.2111950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 08/03/2022] [Indexed: 02/04/2023] Open
Abstract
Melioidosis is a disease caused by the Gram-negative bacillus Burkholderia pseudomallei (Bpm), commonly found in soil and water of endemic areas. Naturally acquired human melioidosis infections can result from either exposure through percutaneous inoculation, inhalation, or ingestion of soil-contaminated food or water. Our prior studies recognized Bpm as an effective enteric pathogen, capable of establishing acute or chronic gastrointestinal infections following oral inoculation. However, the specific mechanisms and virulence factors involved in the pathogenesis of Bpm during intestinal infection are unknown. In our current study, we standardized an in vitro intestinal infection model using primary intestinal epithelial cells (IECs) and demonstrated that Bpm requires a functional T6SS for full virulence. Further, we performed dual RNA-seq analysis on Bpm-infected IECs to evaluate differentially expressed host and bacterial genes in the presence or absence of a T6SS. Our results showed a dysregulation in the TNF-α signaling via NF-κB pathway in the absence of the T6SS, with some of the genes involved in inflammatory processes and cell death also affected. Analysis of the bacterial transcriptome identified virulence factors and regulatory proteins playing a role during infection, with association to the T6SS. By using a Bpm transposon mutant library and isogenic mutants, we showed that deletion of the bicA gene, encoding a putative T3SS/T6SS regulator, ablated intracellular survival and plaque formation by Bpm and impacted survival and virulence when using murine models of acute and chronic gastrointestinal infection. Overall, these results highlight the importance of the type 6 secretion system in the gastrointestinal pathogenesis of Bpm.
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Affiliation(s)
| | - Daniel Tapia
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Nittaya Khakhum
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Steven G. Widen
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Alfredo G. Torres
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
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14
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Saini S, Singha H, Shanmugasundaram K, Tripathi BN. Characterization of immunoglobulin and cytokine responses in Burkholderia mallei infected equids. Microb Pathog 2021; 162:105310. [PMID: 34838612 DOI: 10.1016/j.micpath.2021.105310] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 11/12/2021] [Accepted: 11/22/2021] [Indexed: 01/30/2023]
Abstract
Burkholderia mallei causes a highly fatal infectious disease in equines known as glanders. It is one of the OIE listed notifiable diseases, which entails strict control policy measures once B. mallei infection is confirmed in the susceptible hosts. Humans, especially equine handlers, veterinary professionals and laboratory workers are at greater risk to acquire the B. mallei infection directly through prolonged contact with glanderous equines, and indirectly through unprotected handling of B. mallei contaminated materials. Further, natural resistance of B. mallei to multiple antibiotics, aerosol transmission, lack of effective vaccine and treatment make this organism a potential agent of biological warfare. Results of experimental B. mallei infection in mouse and non-human primates and immunization with live attenuated B. mallei strains demonstrated that activation of early innate and adaptive immune responses play a critical role in controlling B. mallei infection. However, the immune response elicited by the primary hosts (equids) B. mallei infection is poorly understood. Therefore, we aimed to investigate immune responses in glanders affected horses (n = 23) and mules (n = 1). In this study, chronically infected equids showed strong humoral responses (IgM, IgG and IgA) specific to B. mallei type 6 secretory proteins such as Hcp1, TssA and TssB. The infected equids also elicited robust cellular responses characterized by significantly elevated levels of IFN-γ, TNF-α, IL-12, IL-17 and IL-6 in PBMCs. In addition, stimulation of equine PBMCs by Hcp1 resulted in the further elevation of these cytokines. Thus, the present study indicated that antibody response and T helper cell (Th) type 1-associated cytokines were the salient features of chronic B. mallei infection in horses. The immune responses also suggest further evaluation of these proteins as potential vaccine candidates.
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Affiliation(s)
- Sheetal Saini
- ICAR-National Research Centre on Equines, Sirsa Road, Hisar, 125001, Haryana, India
| | - Harisankar Singha
- ICAR-National Research Centre on Equines, Sirsa Road, Hisar, 125001, Haryana, India.
| | - Karuppusamy Shanmugasundaram
- National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Sirsa Road, Hisar, 125001, Haryana, India
| | - Bhupendra Nath Tripathi
- Division of Animal Sciences, Indian Council of Agricultural Research, Krishi Bhavan, New Delhi, 110 001, India.
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15
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Recent Progress in Shigella and Burkholderia pseudomallei Vaccines. Pathogens 2021; 10:pathogens10111353. [PMID: 34832508 PMCID: PMC8621228 DOI: 10.3390/pathogens10111353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/15/2021] [Accepted: 10/18/2021] [Indexed: 12/28/2022] Open
Abstract
Significant advancement has been made in the development of vaccines against bacterial pathogens. However, several roadblocks have been found during the evaluation of vaccines against intracellular bacterial pathogens. Therefore, new lessons could be learned from different vaccines developed against unrelated intracellular pathogens. Bacillary dysentery and melioidosis are important causes of morbidity and mortality in developing nations, which are caused by the intracellular bacteria Shigella and Burkholderia pseudomallei, respectively. Although the mechanisms of bacterial infection, dissemination, and route of infection do not provide clues about the commonalities of the pathogenic infectious processes of these bacteria, a wide variety of vaccine platforms recently evaluated suggest that in addition to the stimulation of antibodies, identifying protective antigens and inducing T cell responses are some additional required elements to induce effective protection. In this review, we perform a comparative evaluation of recent candidate vaccines used to combat these two infectious agents, emphasizing the common strategies that can help investigators advance effective and protective vaccines to clinical trials.
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16
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Grund ME, Kramarska E, Choi SJ, McNitt DH, Klimko CP, Rill NO, Dankmeyer JL, Shoe JL, Hunter M, Fetterer DP, Hedrick ZM, Velez I, Biryukov SS, Cote CK, Berisio R, Lukomski S. Predictive and Experimental Immunogenicity of Burkholderia Collagen-like Protein 8-Derived Antigens. Vaccines (Basel) 2021; 9:vaccines9111219. [PMID: 34835150 PMCID: PMC8621890 DOI: 10.3390/vaccines9111219] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 10/15/2021] [Accepted: 10/18/2021] [Indexed: 11/25/2022] Open
Abstract
Burkholderia pseudomallei is an infectious bacterium of clinical and biodefense concern, and is the causative agent of melioidosis. The mortality rate can reach up to 50% and affects 165,000 people per year; however, there is currently no vaccine available. In this study, we examine the antigen-specific immune response to a vaccine formulated with antigens derived from an outer membrane protein in B. pseudomallei, Bucl8. Here, we employed a number of bioinformatic tools to predict Bucl8-derived epitopes that are non-allergenic and non-toxic, but would elicit an immune response. From these data, we formulated a vaccine based on two extracellular components of Bucl8, the β-barrel loops and extended collagen and non-collagen domains. Outbred CD-1 mice were immunized with vaccine formulations—composed of recombinant proteins or conjugated synthetic peptides with adjuvant—to assess the antigen-specific immune responses in mouse sera and lymphoid organs. We found that mice vaccinated with either Bucl8-derived components generated a robust TH2-skewed antibody response when antigen was combined with the adjuvant AddaVax, while the TH1 response was limited. Mice immunized with synthetic loop peptides had a stronger, more consistent antibody response than recombinant protein antigens, based on higher IgG titers and recognition of bacteria. We then compared peptide-based vaccines in an established C57BL/6 inbred mouse model and observed a similar TH2-skewed response. The resulting formulations will be applied in future studies examining the protection of Bucl8-derived vaccines.
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Affiliation(s)
- Megan E. Grund
- Department of Microbiology, Immunology and Cell Biology, School of Medicine, West Virginia University, Morgantown, WV 26506, USA; (M.E.G.); (S.J.C.); (D.H.M.)
| | - Eliza Kramarska
- Institute of Biostructures and Bioimaging, National Research Council (CNR-IBB), 80134 Naples, Italy; (E.K.); (R.B.)
| | - Soo Jeon Choi
- Department of Microbiology, Immunology and Cell Biology, School of Medicine, West Virginia University, Morgantown, WV 26506, USA; (M.E.G.); (S.J.C.); (D.H.M.)
| | - Dudley H. McNitt
- Department of Microbiology, Immunology and Cell Biology, School of Medicine, West Virginia University, Morgantown, WV 26506, USA; (M.E.G.); (S.J.C.); (D.H.M.)
| | - Christopher P. Klimko
- Bacteriology Division, The United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD 21702, USA; (C.P.K.); (N.O.R.); (J.L.D.); (J.L.S.); (M.H.); (Z.M.H.); (I.V.); (S.S.B.); (C.K.C.)
| | - Nathaniel O. Rill
- Bacteriology Division, The United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD 21702, USA; (C.P.K.); (N.O.R.); (J.L.D.); (J.L.S.); (M.H.); (Z.M.H.); (I.V.); (S.S.B.); (C.K.C.)
| | - Jennifer L. Dankmeyer
- Bacteriology Division, The United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD 21702, USA; (C.P.K.); (N.O.R.); (J.L.D.); (J.L.S.); (M.H.); (Z.M.H.); (I.V.); (S.S.B.); (C.K.C.)
| | - Jennifer L. Shoe
- Bacteriology Division, The United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD 21702, USA; (C.P.K.); (N.O.R.); (J.L.D.); (J.L.S.); (M.H.); (Z.M.H.); (I.V.); (S.S.B.); (C.K.C.)
| | - Melissa Hunter
- Bacteriology Division, The United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD 21702, USA; (C.P.K.); (N.O.R.); (J.L.D.); (J.L.S.); (M.H.); (Z.M.H.); (I.V.); (S.S.B.); (C.K.C.)
| | - David P. Fetterer
- Biostatistics Division, The United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD 21702, USA;
| | - Zander M. Hedrick
- Bacteriology Division, The United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD 21702, USA; (C.P.K.); (N.O.R.); (J.L.D.); (J.L.S.); (M.H.); (Z.M.H.); (I.V.); (S.S.B.); (C.K.C.)
| | - Ivan Velez
- Bacteriology Division, The United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD 21702, USA; (C.P.K.); (N.O.R.); (J.L.D.); (J.L.S.); (M.H.); (Z.M.H.); (I.V.); (S.S.B.); (C.K.C.)
| | - Sergei S. Biryukov
- Bacteriology Division, The United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD 21702, USA; (C.P.K.); (N.O.R.); (J.L.D.); (J.L.S.); (M.H.); (Z.M.H.); (I.V.); (S.S.B.); (C.K.C.)
| | - Christopher K. Cote
- Bacteriology Division, The United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD 21702, USA; (C.P.K.); (N.O.R.); (J.L.D.); (J.L.S.); (M.H.); (Z.M.H.); (I.V.); (S.S.B.); (C.K.C.)
| | - Rita Berisio
- Institute of Biostructures and Bioimaging, National Research Council (CNR-IBB), 80134 Naples, Italy; (E.K.); (R.B.)
| | - Slawomir Lukomski
- Department of Microbiology, Immunology and Cell Biology, School of Medicine, West Virginia University, Morgantown, WV 26506, USA; (M.E.G.); (S.J.C.); (D.H.M.)
- Correspondence:
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17
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D'haeseleer P, Collette NM, Lao V, Segelke BW, Branda SS, Franco M. Shotgun Immunoproteomic Approach for the Discovery of Linear B-Cell Epitopes in Biothreat Agents Francisella tularensis and Burkholderia pseudomallei. Front Immunol 2021; 12:716676. [PMID: 34659206 PMCID: PMC8513525 DOI: 10.3389/fimmu.2021.716676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Accepted: 09/02/2021] [Indexed: 11/13/2022] Open
Abstract
Peptide-based subunit vaccines are coming to the forefront of current vaccine approaches, with safety and cost-effective production among their top advantages. Peptide vaccine formulations consist of multiple synthetic linear epitopes that together trigger desired immune responses that can result in robust immune memory. The advantages of linear compared to conformational epitopes are their simple structure, ease of synthesis, and ability to stimulate immune responses by means that do not require complex 3D conformation. Prediction of linear epitopes through use of computational tools is fast and cost-effective, but typically of low accuracy, necessitating extensive experimentation to verify results. On the other hand, identification of linear epitopes through experimental screening has been an inefficient process that requires thorough characterization of previously identified full-length protein antigens, or laborious techniques involving genetic manipulation of organisms. In this study, we apply a newly developed generalizable screening method that enables efficient identification of B-cell epitopes in the proteomes of pathogenic bacteria. As a test case, we used this method to identify epitopes in the proteome of Francisella tularensis (Ft), a Select Agent with a well-characterized immunoproteome. Our screen identified many peptides that map to known antigens, including verified and predicted outer membrane proteins and extracellular proteins, validating the utility of this approach. We then used the method to identify seroreactive peptides in the less characterized immunoproteome of Select Agent Burkholderia pseudomallei (Bp). This screen revealed known Bp antigens as well as proteins that have not been previously identified as antigens. Although B-cell epitope prediction tools Bepipred 2.0 and iBCE-EL classified many of our seroreactive peptides as epitopes, they did not score them significantly higher than the non-reactive tryptic peptides in our study, nor did they assign higher scores to seroreactive peptides from known Ft or Bp antigens, highlighting the need for experimental data instead of relying on computational epitope predictions alone. The present workflow is easily adaptable to detecting peptide targets relevant to the immune systems of other mammalian species, including humans (depending upon the availability of convalescent sera from patients), and could aid in accelerating the discovery of B-cell epitopes and development of vaccines to counter emerging biological threats.
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Affiliation(s)
- Patrik D'haeseleer
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Nicole M Collette
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Victoria Lao
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Brent W Segelke
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Steven S Branda
- Molecular and Microbiology Department, Sandia National Laboratories, Livermore, CA, United States
| | - Magdalena Franco
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA, United States
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18
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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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19
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Sengyee S, Yarasai A, Janon R, Morakot C, Ottiwet O, Schmidt LK, West TE, Burtnick MN, Chantratita N, Brett PJ. Melioidosis Patient Survival Correlates With Strong IFN-γ Secreting T Cell Responses Against Hcp1 and TssM. Front Immunol 2021; 12:698303. [PMID: 34394091 PMCID: PMC8363298 DOI: 10.3389/fimmu.2021.698303] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 07/19/2021] [Indexed: 11/13/2022] Open
Abstract
Melioidosis, caused by the Gram-negative bacterium Burkholderia pseudomallei, is a serious infectious disease with diverse clinical manifestations. The morbidity and mortality of melioidosis is high in Southeast Asia and no licensed vaccines currently exist. This study was aimed at evaluating human cellular and humoral immune responses in Thai adults against four melioidosis vaccine candidate antigens. Blood samples from 91 melioidosis patients and 100 healthy donors from northeast Thailand were examined for immune responses against B. pseudomallei Hcp1, AhpC, TssM and LolC using a variety of cellular and humoral immune assays including IFN-γ ELISpot assays, flow cytometry and ELISA. PHA and a CPI peptide pool were also used as control stimuli in the ELISpot assays. Hcp1 and TssM stimulated strong IFN-γ secreting T cell responses in acute melioidosis patients which correlated with survival. High IFN-γ secreting CD4+ T cell responses were observed during acute melioidosis. Interestingly, while T cell responses of melioidosis patients against the CPI peptide pool were low at the time of enrollment, the levels increased to the same as in healthy donors by day 28. Although high IgG levels against Hcp1 and AhpC were detected in acute melioidosis patients, no significant differences between survivors and non-survivors were observed. Collectively, these studies help to further our understanding of immunity against disease following natural exposure of humans to B. pseudomallei as well as provide important insights for the selection of candidate antigens for use in the development of safe and effective melioidosis subunit vaccines.
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Affiliation(s)
- Sineenart Sengyee
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Atchara Yarasai
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Rachan Janon
- Department of Medicine, Mukdahan Hospital, Mukdahan, Thailand
| | - Chumpol Morakot
- Department of Medicine, Mukdahan Hospital, Mukdahan, Thailand
| | - Orawan Ottiwet
- Department of Medicine, Mukdahan Hospital, Mukdahan, Thailand
| | - Lindsey K. Schmidt
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, NV, United States
| | - T. Eoin West
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Division of Pulmonary, Critical Care & Sleep Medicine, Harborview Medical Center, University of Washington, Seattle, WA, United States
- International Respiratory and Severe Illness Center, University of Washington, Seattle, WA, United States
| | - Mary N. Burtnick
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, NV, United States
| | - Narisara Chantratita
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Paul J. Brett
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, NV, United States
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20
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Multicomponent Gold-Linked Glycoconjugate Vaccine Elicits Antigen-Specific Humoral and Mixed T H1-T H17 Immunity, Correlated with Increased Protection against Burkholderia pseudomallei. mBio 2021; 12:e0122721. [PMID: 34182777 PMCID: PMC8263005 DOI: 10.1128/mbio.01227-21] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Burkholderia pseudomallei is the causative agent of melioidosis, a fatal disease with a high mortality rate. The intrinsic resistance to commonly used antibiotics combined with the complex bacterial life cycle has hampered the development of preventive and therapeutic interventions and vaccines. Furthermore, the need of humoral and cell-mediated immunity in protection against B. pseudomallei has complicated the development of effective vaccines. Antigen delivery vaccine platforms that promote humoral and cellular responses while maintaining a safe profile are a roadblock to developing subunit vaccines against intracellular pathogens. Gold nanoparticles (AuNPs) were used for the delivery of multicomponent antigens with the goal of inducing vaccine-mediated immunity, promoting protection against melioidosis disease. Different nanoglycoconjugates using predicted immunogenic protein candidates, Hcp1, FlgL, OpcP, OpcP1, OmpW, and hemagglutinin, were covalently coupled to AuNPs, together with the lipopolysaccharide (LPS) from Burkholderia thailandensis, which acted as an additional antigen. Animals immunized with individually coupled (AuNP-protein-LPS) formulations containing OpcP or OpcP1, together with CpG as an adjuvant, showed a significant increase in protection, whereas a nanovaccine combination (AuNP-Combo2-LPS) showed significant and complete protection against a lethal intranasal B. pseudomallei challenge. Animals immunized with AuNP-Combo2-LPS showed robust humoral antigen-specific (IgG and IgA) responses with higher IgG2c titer, indicating a TH1-skewed response and promotion of macrophage uptake. In addition, immunization with the nanovaccine combination resulted in a mixed antigen-specific TH1-TH17 cytokine profile after immunization. This study provides the basis for an elegant and refined multicomponent glycoconjugate vaccine formulation capable of eliciting both humoral and cell-mediated responses against lethal B. pseudomallei challenge.
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21
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Potempa J, Madej M, Scott DA. The RagA and RagB proteins of Porphyromonas gingivalis. Mol Oral Microbiol 2021; 36:225-232. [PMID: 34032024 DOI: 10.1111/omi.12345] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 05/05/2021] [Accepted: 05/07/2021] [Indexed: 11/27/2022]
Abstract
RagA and RagB proteins are major components of the outer membrane of the oral pathogen Porphyromonas gingivalis and, while recently suggested to represent a novel peptide uptake system, their full function is still under investigation. Herein, we (a) discuss the evidence that the rag locus contributes to P. gingivalis virulence; (b) provide insight to Rag protein potential biological function in macromolecular transport and other aspects of bacterial physiology; (c) address the host response to Rag proteins which are immunodominant and immunomodulatory; and (d) review the potential of Rag-focused therapeutic strategies for the control of periodontal diseases.
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Affiliation(s)
- Jan Potempa
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, Kentucky, USA.,Faculty of Biochemistry, Biophysics and Biotechnology, Department of Microbiology, Jagiellonian University, Kraków, Poland
| | - Mariusz Madej
- Faculty of Biochemistry, Biophysics and Biotechnology, Department of Microbiology, Jagiellonian University, Kraków, Poland
| | - David A Scott
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, Kentucky, USA
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22
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Khakhum N, Bharaj P, Walker DH, Torres AG, Endsley JJ. Antigen-specific antibody and polyfunctional T cells generated by respiratory immunization with protective Burkholderia ΔtonB Δhcp1 live attenuated vaccines. NPJ Vaccines 2021; 6:72. [PMID: 33986290 PMCID: PMC8119421 DOI: 10.1038/s41541-021-00333-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 03/18/2021] [Indexed: 11/09/2022] Open
Abstract
Melioidosis, caused by Burkholderia pseudomallei (Bpm), lacks a vaccine. We identify the immune correlates of protection induced by B. mallei ΔtonB Δhcp1 (CLH001) and Bpm ΔtonB Δhcp1 (PBK001) vaccines against inhalational melioidosis. Mucosal immunization with either vaccine generates Bpm-specific IgM and IgG (IgG2b/c > IgG1 > IgG3) antibodies in sera and lungs, and lung IgA antibodies. Sera confers complement-independent bactericidal activity and macrophages opsonophagocytic uptake but is insufficient in passive transfer experiments to provide significant protection. Both vaccines elicit memory Th1 and Th17 CD4+ T-cell responses in lung and spleen after Bpm antigen-specific recall. The PBK001 vaccine is superior in generating respiratory IgA post-boost, anamnestic IgG at challenge, T-cell recall to specific antigen, and development of diverse polyfunctional memory T-cell pools. Analysis of lung histology suggests that potent polyfunctional T-cell memory and/or IL-17 signatures generated with PBK001 vaccination may be associated with moderate lung inflammation post vaccination.
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Affiliation(s)
- Nittaya Khakhum
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA
| | - Preeti Bharaj
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA
| | - David H Walker
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA
| | - Alfredo G Torres
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA. .,Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA.
| | - Janice J Endsley
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA.
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23
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Waag DM, Chance TB, Trevino SR, Rossi FD, Fetterer DP, Amemiya K, Dankmeyer JL, Ingavale SS, Tobery SA, Zeng X, Kern SJ, Worsham PL, Cote CK, Welkos SL. Comparison of three non-human primate aerosol models for glanders, caused by Burkholderia mallei. Microb Pathog 2021; 155:104919. [PMID: 33915206 DOI: 10.1016/j.micpath.2021.104919] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 03/30/2021] [Accepted: 04/01/2021] [Indexed: 01/15/2023]
Abstract
Burkholderia mallei is a gram-negative obligate animal pathogen that causes glanders, a highly contagious and potentially fatal disease of solipeds including horses, mules, and donkeys. Humans are also susceptible, and exposure can result in a wide range of clinical forms, i.e., subclinical infection, chronic forms with remission and exacerbation, or acute and potentially lethal septicemia and/or pneumonia. Due to intrinsic antibiotic resistance and the ability of the organisms to survive intracellularly, current treatment regimens are protracted and complicated; and no vaccine is available. As a consequence of these issues, and since B. mallei is infectious by the aerosol route, B. mallei is regarded as a major potential biothreat agent. To develop optimal medical countermeasures and diagnostic tests, well characterized animal models of human glanders are needed. The goal of this study was to perform a head-to-head comparison of models employing three commonly used nonhuman primate (NHP) species, the African green monkey (AGM), Rhesus macaque, and the Cynomolgus macaque. The natural history of infection and in vitro clinical, histopathological, immunochemical, and bacteriological parameters were examined. The AGMs were the most susceptible NHP to B. mallei; five of six expired within 14 days. Although none of the Rhesus or Cynomolgus macaques succumbed, the Rhesus monkeys exhibited abnormal signs and clinical findings associated with B. mallei infection; and the latter may be useful for modeling chronic B. mallei infection. Based on the disease progression observations, gross and histochemical pathology, and humoral and cellular immune response findings, the AGM appears to be the optimal model of acute, lethal glanders infection. AGM models of infection by B. pseudomallei, the etiologic agent of melioidosis, have been characterized recently. Thus, the selection of the AGM species provides the research community with a single NHP model for investigations on acute, severe, inhalational melioidosis and glanders.
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Affiliation(s)
- David M Waag
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, USA
| | - Taylor B Chance
- Pathology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, USA
| | - Sylvia R Trevino
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, USA
| | - Franco D Rossi
- Applied and Advanced Technology-Aerobiology, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, USA
| | - David P Fetterer
- Biostatistics Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, USA
| | - Kei Amemiya
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, USA
| | - Jennifer L Dankmeyer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, USA
| | - Susham S Ingavale
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, USA
| | - Steven A Tobery
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, USA
| | - Xiankun Zeng
- Pathology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, USA
| | - Steven J Kern
- Biostatistics Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, USA
| | - Patricia L Worsham
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, USA
| | - Christopher K Cote
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, USA.
| | - Susan L Welkos
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, USA.
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24
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Grund ME, Choi Soo J, Cote CK, Berisio R, Lukomski S. Thinking Outside the Bug: Targeting Outer Membrane Proteins for Burkholderia Vaccines. Cells 2021; 10:cells10030495. [PMID: 33668922 PMCID: PMC7996558 DOI: 10.3390/cells10030495] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/18/2021] [Accepted: 02/22/2021] [Indexed: 12/16/2022] Open
Abstract
Increasing antimicrobial resistance due to misuse and overuse of antimicrobials, as well as a lack of new and innovative antibiotics in development has become an alarming global threat. Preventative therapeutics, like vaccines, are combative measures that aim to stop infections at the source, thereby decreasing the overall use of antibiotics. Infections due to Gram-negative pathogens pose a significant treatment challenge because of substantial multidrug resistance that is acquired and spread throughout the bacterial population. Burkholderia spp. are Gram-negative intrinsically resistant bacteria that are responsible for environmental and nosocomial infections. The Burkholderia cepacia complex are respiratory pathogens that primarily infect immunocompromised and cystic fibrosis patients, and are acquired through contaminated products and equipment, or via patient-to-patient transmission. The Burkholderia pseudomallei complex causes percutaneous wound, cardiovascular, and respiratory infections. Transmission occurs through direct exposure to contaminated water, water-vapors, or soil, leading to the human disease melioidosis, or the equine disease glanders. Currently there is no licensed vaccine against any Burkholderia pathogen. This review will discuss Burkholderia vaccine candidates derived from outer membrane proteins, OmpA, OmpW, Omp85, and Bucl8, encompassing their structures, conservation, and vaccine formulation.
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Affiliation(s)
- Megan E. Grund
- Department of Microbiology, Immunology and Cell Biology, School of Medicine, West Virginia University, Morgantown, WV 26506, USA; (M.E.G.); (S.J.C.)
| | - Jeon Choi Soo
- Department of Microbiology, Immunology and Cell Biology, School of Medicine, West Virginia University, Morgantown, WV 26506, USA; (M.E.G.); (S.J.C.)
| | - Christopher K. Cote
- Bacteriology Division, The United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD 21702, USA;
| | - Rita Berisio
- Institute of Biostructures and Bioimaging, National Research Council (CNR-IBB), 80145 Naples, Italy;
| | - Slawomir Lukomski
- Department of Microbiology, Immunology and Cell Biology, School of Medicine, West Virginia University, Morgantown, WV 26506, USA; (M.E.G.); (S.J.C.)
- Correspondence: ; Tel.: +1-304-293-6405
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25
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Schuit M, Gardner S, Taylor J, Dabisch P. Evaluation of four sampling devices for Burkholderia pseudomallei laboratory aerosol studies. PLoS Negl Trop Dis 2021; 15:e0009001. [PMID: 33524051 PMCID: PMC7850477 DOI: 10.1371/journal.pntd.0009001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 11/21/2020] [Indexed: 11/18/2022] Open
Abstract
Previous field and laboratory studies investigating airborne Burkholderia pseudomallei have used a variety of different aerosol samplers to detect and quantify concentrations of the bacteria in aerosols. However, the performance of aerosol samplers can vary in their ability to preserve the viability of collected microorganisms, depending on the resistance of the organisms to impaction, desiccation, or other stresses associated with the sampling process. Consequently, sampler selection is critical to maximizing the probability of detecting viable microorganisms in collected air samples in field studies and for accurate determination of aerosol concentrations in laboratory studies. To inform such decisions, the present study assessed the performance of four laboratory aerosol samplers, specifically the all-glass impinger (AGI), gelatin filter, midget impinger, and Mercer cascade impactor, for collecting aerosols containing B. pseudomallei generated from suspensions in two types of culture media. The results suggest that the relative performance of the sampling devices is dependent on the suspension medium utilized for aerosolization. Performance across the four samplers was similar for aerosols generated from suspensions supplemented with 4% glycerol. However, for aerosols generated from suspensions without glycerol, use of the filter sampler or an impactor resulted in significantly lower estimates of the viable aerosol concentration than those obtained with either the AGI or midget impinger. These results demonstrate that sampler selection has the potential to affect estimation of doses in inhalational animal models of melioidosis, as well as the likelihood of detection of viable B. pseudomallei in the environment, and will be useful to inform design of future laboratory and field studies.
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Affiliation(s)
- Michael Schuit
- National Biodefense Analysis and Countermeasures Center, Operated by BNBI for the U.S. Department of Homeland Security Science and Technology Directorate, Frederick, Maryland, United States of America
- School of Systems Biology, George Mason University, Manassas, Virginia, United States of America
| | - Sierra Gardner
- National Biodefense Analysis and Countermeasures Center, Operated by BNBI for the U.S. Department of Homeland Security Science and Technology Directorate, Frederick, Maryland, United States of America
| | - Jill Taylor
- National Biodefense Analysis and Countermeasures Center, Operated by BNBI for the U.S. Department of Homeland Security Science and Technology Directorate, Frederick, Maryland, United States of America
| | - Paul Dabisch
- National Biodefense Analysis and Countermeasures Center, Operated by BNBI for the U.S. Department of Homeland Security Science and Technology Directorate, Frederick, Maryland, United States of America
- School of Systems Biology, George Mason University, Manassas, Virginia, United States of America
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26
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Burkholderia pseudomallei OMVs derived from infection mimicking conditions elicit similar protection to a live-attenuated vaccine. NPJ Vaccines 2021; 6:18. [PMID: 33514749 PMCID: PMC7846723 DOI: 10.1038/s41541-021-00281-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 01/07/2021] [Indexed: 02/07/2023] Open
Abstract
Burkholderia pseudomallei is a Gram-negative, facultative intracellular bacillus that causes the disease melioidosis. B. pseudomallei expresses a number of proteins that contribute to its intracellular survival in the mammalian host. We previously demonstrated that immunization with OMVs derived from B. pseudomallei grown in nutrient-rich media protects mice against lethal disease. Here, we evaluated if OMVs derived from B. pseudomallei grown under macrophage-mimicking growth conditions could be enriched with intracellular-stage proteins in order to improve the vaccine. We show that OMVs produced in this manner (M9 OMVs) contain proteins associated with intracellular survival yet are non-toxic to living cells. Immunization of mice provides significant protection against pulmonary infection similar to that achieved with a live attenuated vaccine and is associated with increased IgG, CD4+, and CD8+ T cells. OMVs possess inherent adjuvanticity and drive DC activation and maturation. These results indicate that M9 OMVs constitute a new promising vaccine against melioidosis.
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27
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Wang G, Zarodkiewicz P, Valvano MA. Current Advances in Burkholderia Vaccines Development. Cells 2020; 9:E2671. [PMID: 33322641 PMCID: PMC7762980 DOI: 10.3390/cells9122671] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 12/01/2020] [Accepted: 12/09/2020] [Indexed: 12/18/2022] Open
Abstract
The genus Burkholderia includes a wide range of Gram-negative bacterial species some of which are pathogenic to humans and other vertebrates. The most pathogenic species are Burkholderia mallei, Burkholderia pseudomallei, and the members of the Burkholderia cepacia complex (Bcc). B. mallei and B. pseudomallei, the cause of glanders and melioidosis, respectively, are considered potential bioweapons. The Bcc comprises a subset of Burkholderia species associated with respiratory infections in people with chronic granulomatous disease and cystic fibrosis. Antimicrobial treatment of Burkholderia infections is difficult due to the intrinsic multidrug antibiotic resistance of these bacteria; prophylactic vaccines provide an attractive alternative to counteract these infections. Although commercial vaccines against Burkholderia infections are still unavailable, substantial progress has been made over recent years in the development of vaccines against B. pseudomallei and B. mallei. This review critically discusses the current advances in vaccine development against B. mallei, B. pseudomallei, and the Bcc.
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Affiliation(s)
| | | | - Miguel A. Valvano
- Wellcome-Wolfson Institute for Experimental Medicine, Queen’s University Belfast, Belfast BT9 7BL, UK; (G.W.); (P.Z.)
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28
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Vezina B, Petit GA, Martin JL, Halili MA. Prediction of Burkholderia pseudomallei DsbA substrates identifies potential virulence factors and vaccine targets. PLoS One 2020; 15:e0241306. [PMID: 33216758 PMCID: PMC7678975 DOI: 10.1371/journal.pone.0241306] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/12/2020] [Indexed: 11/19/2022] Open
Abstract
Identification of bacterial virulence factors is critical for understanding disease pathogenesis, drug discovery and vaccine development. In this study we used two approaches to predict virulence factors of Burkholderia pseudomallei, the Gram-negative bacterium that causes melioidosis. B. pseudomallei is naturally antibiotic resistant and there are no clinically available melioidosis vaccines. To identify B. pseudomallei protein targets for drug discovery and vaccine development, we chose to search for substrates of the B. pseudomallei periplasmic disulfide bond forming protein A (DsbA). DsbA introduces disulfide bonds into extra-cytoplasmic proteins and is essential for virulence in many Gram-negative organism, including B. pseudomallei. The first approach to identify B. pseudomallei DsbA virulence factor substrates was a large-scale genomic analysis of 511 unique B. pseudomallei disease-associated strains. This yielded 4,496 core gene products, of which we hypothesise 263 are DsbA substrates. Manual curation and database screening of the 263 mature proteins yielded 81 associated with disease pathogenesis or virulence. These were screened for structural homologues to predict potential B-cell epitopes. In the second approach, we searched the B. pseudomallei genome for homologues of the more than 90 known DsbA substrates in other bacteria. Using this approach, we identified 15 putative B. pseudomallei DsbA virulence factor substrates, with two of these previously identified in the genomic approach, bringing the total number of putative DsbA virulence factor substrates to 94. The two putative B. pseudomallei virulence factors identified by both methods are homologues of PenI family β-lactamase and a molecular chaperone. These two proteins could serve as high priority targets for future B. pseudomallei virulence factor characterization.
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Affiliation(s)
- Ben Vezina
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia
| | - Guillaume A. Petit
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia
| | - Jennifer L. Martin
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia
- Vice-Chancellor’s Unit, University of Wollongong, Wollongong, New South Wales, Australia
| | - Maria A. Halili
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia
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29
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Lin HH, Filloux A, Lai EM. Role of Recipient Susceptibility Factors During Contact-Dependent Interbacterial Competition. Front Microbiol 2020; 11:603652. [PMID: 33281802 PMCID: PMC7690452 DOI: 10.3389/fmicb.2020.603652] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 10/13/2020] [Indexed: 11/13/2022] Open
Abstract
Bacteria evolved multiple strategies to survive and develop optimal fitness in their ecological niche. They deployed protein secretion systems for robust and efficient delivery of antibacterial toxins into their target cells, therefore inhibiting their growth or killing them. To maximize antagonism, recipient factors on target cells can be recognized or hijacked to enhance the entry or toxicity of these toxins. To date, knowledge regarding recipient susceptibility (RS) factors and their mode of action is mostly originating from studies on the type Vb secretion system that is also known as the contact-dependent inhibition (CDI) system. Yet, recent studies on the type VI secretion system (T6SS), and the CDI by glycine-zipper protein (Cdz) system, also reported the emerging roles of RS factors in interbacterial competition. Here, we review these RS factors and their mechanistic impact in increasing susceptibility of recipient cells in response to CDI, T6SS, and Cdz. Past and future strategies for identifying novel RS factors are also discussed, which will help in understanding the interplay between attacker and prey upon secretion system-dependent competition. Understanding these mechanisms would also provide insights for developing novel antibacterial strategies to antagonize aggressive bacteria-killing pathogens.
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Affiliation(s)
- Hsiao-Han Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Alain Filloux
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
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30
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Chaichana P, Kronsteiner B, Rongkard P, Teparrukkul P, Limmathurotsakul D, Chantratita N, Day NPJ, Fletcher HA, Dunachie SJ. Serum From Melioidosis Survivors Diminished Intracellular Burkholderia pseudomallei Growth in Macrophages: A Brief Research Report. Front Cell Infect Microbiol 2020; 10:442. [PMID: 32984070 PMCID: PMC7479196 DOI: 10.3389/fcimb.2020.00442] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 07/20/2020] [Indexed: 11/18/2022] Open
Abstract
Melioidosis is a neglected tropical disease with high mortality rate. It is caused by the Gram-negative, CDC category B select agent Burkholderia pseudomallei (B. ps) that is intrinsically resistant to first-line antibiotics. An antibody-based vaccine is likely to be the most effective control measure. Previous studies have demonstrated significant mechanistic roles of antibodies in protection against death in animal models, but data from human melioidosis is scarce. Herein, we used in-vitro antibody-dependent cellular phagocytosis and growth inhibition assays to assess the mechanism of protective antibodies in patients with acute melioidosis. We found that serum from patients who survived the disease enable more live B. ps to be engulfed by THP-1 derived macrophages (median 1.7 × 103 CFU/ml, IQR 1.1 × 103-2.5 × 103 CFU/ml) than serum from patients who did not survive (median 1.2 × 103 CFU/ml, IQR 0.7 × 103-1.8 × 103, p = 0.02). In addition, the intracellular growth rate of B. ps pre-opsonized with serum from survivors (median 7.89, IQR 5.58–10.85) was diminished when compared with those with serum from non-survivors (median 10.88, IQR 5.42–14.88, p = 0.04). However, the difference of intracellular bacterial growth rate failed to reach statistical significance when using purified IgG antibodies (p = 0.09). These results provide new insights into a mechanistic role of serum in protection against death in human melioidosis for antibody-based vaccine development.
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Affiliation(s)
- Panjaporn Chaichana
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Barbara Kronsteiner
- Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, United Kingdom.,Center for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom
| | - Patpong Rongkard
- Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, United Kingdom
| | - Prapit Teparrukkul
- Medical Department, Sunpasitthiprasong Hospital, Ubon Ratchathani, Thailand
| | - Direk Limmathurotsakul
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Center for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom.,Department of Tropical Hygiene, Mahidol University, Bangkok, Thailand
| | - Narisara Chantratita
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Nicholas P J Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Center for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom
| | - Helen A Fletcher
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Susanna J Dunachie
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, United Kingdom.,Center for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom
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31
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Khakhum N, Chapartegui-González I, Torres AG. Combating the great mimicker: latest progress in the development of Burkholderia pseudomallei vaccines. Expert Rev Vaccines 2020; 19:653-660. [PMID: 32669008 DOI: 10.1080/14760584.2020.1791089] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Introduction Burkholderia pseudomallei is an environmental intracellular Gram-negative bacterium that causes melioidosis, a severe infectious disease affecting humans and animals. An increase in melioidosis cases worldwide and the high mortality rate of the disease makes it a public health concern. Melioidosis is known as the 'great mimicker' because it presents with a wide range of disease manifestations. B. pseudomallei is naturally resistant to antibiotics and delay in diagnosis leads to ineffective treatment. Furthermore, there is no approved vaccine to prevent melioidosis infection in humans. Therefore, it is a priority to license a vaccine that can be used for both high-risk endemic areas and for biodefense purposes. Areas covered In this review, we have focussed on recent progress in the USA for the development and advancement of lead B. pseudomallei vaccine candidate(s) ready for testing in pre-clinical trials. Those candidates include live-attenuated vaccines, glycoconjugate vaccines, outer-membrane vesicles, and gold nanoparticle vaccines. Expert opinion Side-by-side comparison of the leading B. pseudomallei vaccine candidates will provide important information to further advance studies into pre-clinical trials. The likelihood of any of these current vaccines becoming the selected candidate that will reduce the occurrence of melioidosis worldwide is closer than ever.
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Affiliation(s)
- Nittaya Khakhum
- Department of Microbiology & Immunology, University of Texas Medical Branch , Galveston, TX, USA
| | | | - Alfredo G Torres
- Department of Microbiology & Immunology, University of Texas Medical Branch , Galveston, TX, USA.,Department of Pathology, University of Texas Medical Branch , Galveston, TX, USA
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32
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Burkholderia pseudomallei pathogenesis and survival in different niches. Biochem Soc Trans 2020; 48:569-579. [PMID: 32167134 DOI: 10.1042/bst20190836] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 02/24/2020] [Accepted: 02/25/2020] [Indexed: 01/16/2023]
Abstract
Burkholderia pseudomallei (Bp) is the causative agent of melioidosis, a disease of the tropics with high clinical mortality rates. To date, no vaccines are approved for melioidosis and current treatment relies on antibiotics. Conversely, common misdiagnosis and high pathogenicity of Bp hamper efforts to fight melioidosis. This bacterium can be isolated from a wide range of niches such as waterlogged fields, stagnant water bodies, salt water bodies and from human and animal clinical specimens. Although extensive studies have been undertaken to elucidate pathogenesis mechanisms of Bp, little is known about how a harmless soil bacterium adapts to different environmental conditions, in particular, the shift to a human host to become a highly virulent pathogen. The bacterium has a large genome encoding an armory of factors that assist the pathogen in surviving under stressful conditions and assuming its role as a deadly intracellular pathogen. This review presents an overview of what is currently known about how the pathogen adapts to different environments. With in-depth understanding of Bp adaptation and survival, more effective therapies for melioidosis can be developed by targeting related genes or proteins that play a major role in the bacteria's survival.
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Abstract
The causative agent of melioidosis, Burkholderia pseudomallei, a tier 1 select agent, is endemic in Southeast Asia and northern Australia, with increased incidence associated with high levels of rainfall. Increasing reports of this condition have occurred worldwide, with estimates of up to 165,000 cases and 89,000 deaths per year. The ecological niche of the organism has yet to be clearly defined, although the organism is associated with soil and water. The culture of appropriate clinical material remains the mainstay of laboratory diagnosis. Identification is best done by phenotypic methods, although mass spectrometric methods have been described. Serology has a limited diagnostic role. Direct molecular and antigen detection methods have limited availability and sensitivity. Clinical presentations of melioidosis range from acute bacteremic pneumonia to disseminated visceral abscesses and localized infections. Transmission is by direct inoculation, inhalation, or ingestion. Risk factors for melioidosis include male sex, diabetes mellitus, alcohol abuse, and immunosuppression. The organism is well adapted to intracellular survival, with numerous virulence mechanisms. Immunity likely requires innate and adaptive responses. The principles of management of this condition are drainage and debridement of infected material and appropriate antimicrobial therapy. Global mortality rates vary between 9% and 70%. Research into vaccine development is ongoing.
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Affiliation(s)
- I Gassiep
- Pathology Queensland, Townsville Hospital, Townsville, Queensland, Australia
- Faculty of Medicine, University of Queensland, Brisbane, Queensland, Australia
| | - M Armstrong
- Pathology Queensland, Townsville Hospital, Townsville, Queensland, Australia
| | - R Norton
- Pathology Queensland, Townsville Hospital, Townsville, Queensland, Australia
- Faculty of Medicine, University of Queensland, Brisbane, Queensland, Australia
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Tapia D, Sanchez-Villamil JI, Torres AG. Emerging role of biologics for the treatment of melioidosis and glanders. Expert Opin Biol Ther 2019; 19:1319-1332. [PMID: 31590578 PMCID: PMC6981286 DOI: 10.1080/14712598.2019.1677602] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 10/03/2019] [Indexed: 12/15/2022]
Abstract
Introduction: Two important pathogenic species within the genus Burkholderia, namely Burkholderia pseudomallei (Bpm) and Burkholderia mallei (Bm), are the causative agents of the life-threatening diseases melioidosis and glanders, respectively. Due to their high mortality rate and potential for aerosolization, they have gained interest as potential biothreat agents and are classified as Tier 1 Select Agents.Areas covered: The manuscript provides an overview of the literature covering the efforts taken in the last 10 years to develop new therapeutics measures against both Bpm and Bm, with attention on novel therapeutic agents.Expert Opinion: As a result of the complicated antibiotic regimens necessary to treat these infections, development of novel therapeutics is needed to treat both diseases. In recent years, the understanding of the pathogenesis of Burkholderia has improved significantly and so have the efforts to develop novel therapeutic agents with high efficacy, either alone, or in combination with conventional antibiotics.
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Affiliation(s)
- Daniel Tapia
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Javier I. Sanchez-Villamil
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Alfredo G. Torres
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
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Khakhum N, Bharaj P, Myers JN, Tapia D, Walker DH, Endsley JJ, Torres AG. Evaluation of Burkholderia mallei ΔtonB Δhcp1 (CLH001) as a live attenuated vaccine in murine models of glanders and melioidosis. PLoS Negl Trop Dis 2019; 13:e0007578. [PMID: 31306423 PMCID: PMC6658008 DOI: 10.1371/journal.pntd.0007578] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 07/25/2019] [Accepted: 06/25/2019] [Indexed: 01/01/2023] Open
Abstract
Background Glanders caused by Burkholderia mallei is a re-emerging zoonotic disease affecting solipeds and humans. Furthermore, B. mallei is genetically related to B. pseudomallei, which is the causative agent of melioidosis. Both facultative intracellular bacteria are classified as tier 1 select biothreat agents. Our previous study with a B. mallei ΔtonB Δhcp1 (CLH001) live-attenuated vaccine demonstrated that it is attenuated, safe and protective against B. mallei wild-type strains in the susceptible BALB/c mouse model. Methodology/Principal finding In our current work, we evaluated the protective efficacy of CLH001 against glanders and melioidosis in the more disease-resistant C57BL/6 mouse strain. The humoral as well as cellular immune responses were also examined. We found that CLH001-immunized mice showed 100% survival against intranasal and aerosol challenge with B. mallei ATCC 23344. Moreover, this vaccine also afforded significant cross-protection against B. pseudomallei K96243, with low level bacterial burden detected in organs. Immunization with a prime and boost regimen of CLH001 induced significantly greater levels of total and subclasses of IgG, and generated antigen-specific splenocyte production of IFN-γ and IL-17A. Interestingly, protection induced by CLH001 is primarily dependent on humoral immunity, while CD4+ and CD8+ T cells played a less critical protective role. Conclusions/Significance Our data indicate that CLH001 serves as an effective live attenuated vaccine to prevent glanders and melioidosis. The quantity and quality of antibody responses as well as improving cell-mediated immune responses following vaccination need to be further investigated prior to advancement to preclinical studies. Glanders (caused by Burkholderia. mallei) and melioidosis (caused by B. pseudomallei) are severe infectious diseases of concern worldwide because of the rising number of cases and mortality rate. The low infectious doses of these two pathogens along with their amenability for aerosolization are factors that could be exploited as potential biothreat agents. Once the diseases have developed in humans and animals, intrinsic resistance to broad classes of antibiotics becomes a challenge for treatment and increases the risk for relapse. The progress in vaccine development demonstrates that live attenuated vaccine strains are the most effective in protection and providing long-lasting immune responses against both diseases. Our data indicate that the B. mallei double mutant (ΔtonB Δhcp1) strain CLH001, is a feasible vaccine candidate to prevent glanders and melioidosis, especially for biodefense and public health purposes.
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Affiliation(s)
- Nittaya Khakhum
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Preeti Bharaj
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Julia N. Myers
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Daniel Tapia
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - David H. Walker
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Janice J. Endsley
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Alfredo G. Torres
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
- * E-mail:
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Morici L, Torres AG, Titball RW. Novel multi-component vaccine approaches for Burkholderia pseudomallei. Clin Exp Immunol 2019; 196:178-188. [PMID: 30963550 DOI: 10.1111/cei.13286] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/20/2018] [Indexed: 12/16/2022] Open
Abstract
Burkholderia pseudomallei is the causative agent of melioidosis. Historically believed to be a relatively rare human disease in tropical countries, a recent study estimated that, worldwide, there are approximately 165 000 human melioidosis cases per year, more than half of whom die. The bacterium is inherently resistant to many antibiotics and treatment of the disease is often protracted and ineffective. There is no licensed vaccine against melioidosis, but a vaccine is predicted to be of value if used in high-risk populations. There has been progress over the last decade in the pursuit of an effective vaccine against melioidosis. Animal models of disease including mouse and non-human primates have been developed, and these models show that antibody responses play a key role in protection against melioidosis. Surprisingly, although B. pseudomallei is an intracellular pathogen there is limited evidence that CD8+ T cells play a role in protection. It is evident that a multi-component vaccine, incorporating one or more protective antigens, will probably be essential for protection because of the pathogen's sophisticated virulence mechanisms as well as strain heterogeneity. Multi-component vaccines in development include glycoconjugates, multivalent subunit preparations, outer membrane vesicles and other nano/microparticle platforms and live-attenuated or inactivated bacteria. A consistent finding with vaccine candidates tested in mice is the ability to induce sterilizing immunity at low challenge doses and extended time to death at higher challenge doses. Further research to identify ways of eliciting more potent immune responses might provide a path for licensing an effective vaccine.
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Affiliation(s)
- L Morici
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA, USA
| | - A G Torres
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - R W Titball
- College of Life and Environmental Science, University of Exeter, Exeter, UK
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Hogan RJ, Lafontaine ER. Antibodies Are Major Drivers of Protection against Lethal Aerosol Infection with Highly Pathogenic Burkholderia spp. mSphere 2019; 4:e00674-18. [PMID: 30602525 PMCID: PMC6315082 DOI: 10.1128/msphere.00674-18] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Burkholderia pseudomallei and Burkholderia mallei are the causative agents of melioidosis and glanders, respectively. There is no vaccine to protect against these highly pathogenic bacteria, and there is concern regarding their emergence as global public health (B. pseudomallei) and biosecurity (B. mallei) threats. In this issue of mSphere, an article by Khakhum and colleagues (N. Khakhum, P. Bharaj, J. N. Myers, D. Tapia, et al., mSphere 4:e00570-18, 2019, https://doi.org/10.1128/mSphere.00570-18) describes a novel vaccination platform with excellent potential for cross-protection against both Burkholderia species. The report also highlights the importance of antibodies in immunity against these facultative intracellular organisms.
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Affiliation(s)
- Robert J Hogan
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
- Department of Veterinary Biosciences and Diagnostic Imaging, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
| | - Eric R Lafontaine
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
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