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Nelson M, Barnes KB, Davies CH, Cote CK, Meinig JM, Biryukov SS, Dyer DN, Frick O, Heine H, Pfefferle DA, Horstman-Smith A, Barbaras J, Harding SV. The BALB/c Mouse Model for the Evaluation of Therapies to Treat Infections with Aerosolized Burkholderia pseudomallei. Antibiotics (Basel) 2023; 12:antibiotics12030506. [PMID: 36978372 PMCID: PMC10044689 DOI: 10.3390/antibiotics12030506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 02/24/2023] [Accepted: 02/28/2023] [Indexed: 03/06/2023] Open
Abstract
Burkholderia pseudomallei, the causative agent of the disease melioidosis, has been isolated from the environment in 45 countries. The treatment of melioidosis is complex, requiring lengthy antibiotic regimens, which can result in the relapse of the disease following treatment cessation. It is important that novel therapies to treat infections with B. pseudomallei be assessed in appropriate animal models, and discussions regarding the different protocols used between laboratories are critical. A ‘deep dive’ was held in October 2020 focusing on the use of the BALB/c mouse model and the inhalational route of infection to evaluate new antibiotic therapies.
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Affiliation(s)
- Michelle Nelson
- Defence Science and Technology Laboratory, Porton Down, Salisbury SP4 0JQ, UK
| | - Kay B. Barnes
- Defence Science and Technology Laboratory, Porton Down, Salisbury SP4 0JQ, UK
| | - Carwyn H. Davies
- Defence Science and Technology Laboratory, Porton Down, Salisbury SP4 0JQ, UK
| | - Christopher K. Cote
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD 21702, USA
| | - J. Matthew Meinig
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD 21702, USA
| | - Sergei S. Biryukov
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD 21702, USA
| | - David N. Dyer
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD 21702, USA
| | - Ondraya Frick
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD 21702, USA
| | - Henry Heine
- Institute for Therapeutic Innovation, University of Florida, Orlando, FL 32827, USA
| | | | | | - Julie Barbaras
- Defense Threat Reduction Agency, Fort Belvoir, VA 22060, USA
| | - Sarah V. Harding
- Defence Science and Technology Laboratory, Porton Down, Salisbury SP4 0JQ, UK
- School of Respiratory Sciences, University of Leicester, Leicester LE1 7RH, UK
- Correspondence:
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Efficacy of Treatment with the Antibiotic Novobiocin against Infection with Bacillus anthracis or Burkholderia pseudomallei. Antibiotics (Basel) 2022; 11:antibiotics11121685. [PMID: 36551342 PMCID: PMC9774170 DOI: 10.3390/antibiotics11121685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 11/07/2022] [Accepted: 11/10/2022] [Indexed: 11/24/2022] Open
Abstract
The microbial pathogens Burkholderia pseudomallei and Bacillus anthracis are unrelated bacteria, yet both are the etiologic agents of naturally occurring diseases in animals and humans and are classified as Tier 1 potential biothreat agents. B. pseudomallei is the gram-negative bacterial agent of melioidosis, a major cause of sepsis and mortality globally in endemic tropical and subtropical regions. B. anthracis is the gram-positive spore-forming bacterium that causes anthrax. Infections acquired by inhalation of these pathogens are challenging to detect early while the prognosis is best; and they possess innate multiple antibiotic resistance or are amenable to engineered resistance. Previous studies showed that the early generation, rarely used aminocoumarin novobiocin was very effective in vitro against a range of highly disparate biothreat agents. The objective of the current research was to begin to characterize the therapeutic efficacy of novobiocin in mouse models of anthrax and melioidosis. The antibiotic was highly efficacious against infections by both pathogens, especially B. pseudomallei. Our results supported the concept that specific older generation antimicrobials can be effective countermeasures against infection by bacterial biothreat agents. Finally, novobiocin was shown to be a potential candidate for inclusion in a combined pre-exposure vaccination and post-exposure treatment strategy designed to target bacterial pathogens refractory to a single medical countermeasure.
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Klimko CP, Shoe JL, Rill NO, Hunter M, Dankmeyer JL, Talyansky Y, Schmidt LK, Orne CE, Fetterer DP, Biryukov SS, Burtnick MN, Brett PJ, DeShazer D, Cote CK. Layered and integrated medical countermeasures against Burkholderia pseudomallei infections in C57BL/6 mice. Front Microbiol 2022; 13:965572. [PMID: 36060756 PMCID: PMC9432870 DOI: 10.3389/fmicb.2022.965572] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
Burkholderia pseudomallei, the gram-negative bacterium that causes melioidosis, is notoriously difficult to treat with antibiotics. A significant effort has focused on identifying protective vaccine strategies to prevent melioidosis. However, when used as individual medical countermeasures both antibiotic treatments (therapeutics or post-exposure prophylaxes) and experimental vaccine strategies remain partially protective. Here we demonstrate that when used in combination, current vaccine strategies (recombinant protein subunits AhpC and/or Hcp1 plus capsular polysaccharide conjugated to CRM197 or the live attenuated vaccine strain B. pseudomallei 668 ΔilvI) and co-trimoxazole regimens can result in near uniform protection in a mouse model of melioidosis due to apparent synergy associated with distinct medical countermeasures. Our results demonstrated significant improvement when examining several suboptimal antibiotic regimens (e.g., 7-day antibiotic course started early after infection or 21-day antibiotic course with delayed initiation). Importantly, this combinatorial strategy worked similarly when either protein subunit or live attenuated vaccines were evaluated. Layered and integrated medical countermeasures will provide novel treatment options for melioidosis as well as diseases caused by other pathogens that are refractory to individual strategies, particularly in the case of engineered, emerging, or re-emerging bacterial biothreat agents.
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Affiliation(s)
- Christopher P. Klimko
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Jennifer L. Shoe
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Nathaniel O. Rill
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Melissa Hunter
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Jennifer L. Dankmeyer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Yuli Talyansky
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, 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, Frederick, MD, United States
| | - Sergei S. Biryukov
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, 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
| | - David DeShazer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Christopher K. Cote
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
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4
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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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Amemiya K, Dankmeyer JL, Bernhards RC, Fetterer DP, Waag DM, Worsham PL, DeShazer D. Activation of Toll-Like Receptors by Live Gram-Negative Bacterial Pathogens Reveals Mitigation of TLR4 Responses and Activation of TLR5 by Flagella. Front Cell Infect Microbiol 2021; 11:745325. [PMID: 34888257 PMCID: PMC8650638 DOI: 10.3389/fcimb.2021.745325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 10/18/2021] [Indexed: 12/27/2022] Open
Abstract
Successful bacterial pathogens have evolved to avoid activating an innate immune system in the host that responds to the pathogen through distinct Toll-like receptors (TLRs). The general class of biochemical components that activate TLRs has been studied extensively, but less is known about how TLRs interact with the class of compounds that are still associated with the live pathogen. Accordingly, we examined the activation of surface assembled TLR 2, 4, and 5 with live Tier 1 Gram-negative pathogens that included Yersinia pestis (plague), Burkholderia mallei (glanders), Burkholderia pseudomallei (melioidosis), and Francisella tularensis (tularemia). We found that Y. pestis CO92 grown at 28°C activated TLR2 and TLR4, but at 37°C the pathogen activated primarily TLR2. Although B. mallei and B. pseudomallei are genetically related, the former microorganism activated predominately TLR4, while the latter activated predominately TLR2. The capsule of wild-type B. pseudomallei 1026b was found to mitigate the activation of TLR2 and TLR4 when compared to a capsule mutant. Live F. tularensis (Ft) Schu S4 did not activate TLR2 or 4, although the less virulent Ft LVS and F. novicida activated only TLR2. B. pseudomallei purified flagellin or flagella attached to the microorganism activated TLR5. Activation of TLR5 was abolished by an antibody to TLR5, or a mutation of fliC, or elimination of the pathogen by filtration. In conclusion, we have uncovered new properties of the Gram-negative pathogens, and their interaction with TLRs of the host. Further studies are needed to include other microorganism to extend our observations with their interaction with TLRs, and to the possibility of leading to new efforts in therapeutics against these pathogens.
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Affiliation(s)
- Kei Amemiya
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, United States
| | - Jennifer L Dankmeyer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, United States
| | - Robert C Bernhards
- Edgewood Chemical Biological Centre, Aberdeen Proving Ground, Edgewood, MD, United States
| | - David P Fetterer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, United States
| | - David M Waag
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, United States
| | - Patricia L Worsham
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, United States
| | - David DeShazer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, United States
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6
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Biryukov S, Dankmeyer JL, Shamsuddin Z, Velez I, Rill NO, Rosario-Acevedo R, Klimko CP, Shoe JL, Hunter M, Ward MD, Cazares LH, Fetterer DP, Bozue JA, Worsham PL, Cote CK, Amemiya K. Impact of Toll-Like Receptor-Specific Agonists on the Host Immune Response to the Yersinia pestis Plague rF1V Vaccine. Front Immunol 2021; 12:726416. [PMID: 34512658 PMCID: PMC8430260 DOI: 10.3389/fimmu.2021.726416] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 08/03/2021] [Indexed: 11/26/2022] Open
Abstract
Relatively recent advances in plague vaccinology have produced the recombinant fusion protein F1-V plague vaccine. This vaccine has been shown to readily protect mice from both bubonic and pneumonic plague. The protection afforded by this vaccine is solely based upon the immune response elicited by the F1 or V epitopes expressed on the F1-V fusion protein. Accordingly, questions remain surrounding its efficacy against infection with non-encapsulated (F1-negative) strains. In an attempt to further optimize the F1-V elicited immune response and address efficacy concerns, we examined the inclusion of multiple toll-like receptor agonists into vaccine regimens. We examined the resulting immune responses and also any protection afforded to mice that were exposed to aerosolized Yersinia pestis. Our data demonstrate that it is possible to further augment the F1-V vaccine strategy in order to optimize and augment vaccine efficacy.
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Affiliation(s)
- Sergei Biryukov
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Jennifer L. Dankmeyer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Zain Shamsuddin
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Ivan Velez
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Nathaniel O. Rill
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Raysa Rosario-Acevedo
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Christopher P. Klimko
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Jennifer L. Shoe
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Melissa Hunter
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Michael D. Ward
- Molecular Biology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Lisa H. Cazares
- Molecular Biology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - David P. Fetterer
- Biostatistics Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Joel A. Bozue
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Patricia L. Worsham
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Christopher K. Cote
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Kei Amemiya
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
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7
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Cote CK, Biryukov SS, Klimko CP, Shoe JL, Hunter M, Rosario-Acevedo R, Fetterer DP, Moody KL, Meyer JR, Rill NO, Dankmeyer JL, Worsham PL, Bozue JA, Welkos SL. Protection Elicited by Attenuated Live Yersinia pestis Vaccine Strains against Lethal Infection with Virulent Y. pestis. Vaccines (Basel) 2021; 9:vaccines9020161. [PMID: 33669472 PMCID: PMC7920443 DOI: 10.3390/vaccines9020161] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/10/2021] [Accepted: 02/10/2021] [Indexed: 12/22/2022] Open
Abstract
The etiologic agent of plague, Yersinia pestis, is a globally distributed pathogen which poses both a natural and adversarial threat. Due largely to the rapid course and high mortality of pneumonic plague, vaccines are greatly needed. Two-component protein vaccines have been unreliable and potentially vulnerable to vaccine resistance. We evaluated the safety and efficacy of eight live Y. pestis strains derived from virulent strains CO92 or KIM6+ and mutated in one or more virulence-associated gene(s) or cured of plasmid pPst. Stringent, single-dose vaccination allowed down-selection of the two safest and most protective vaccine candidates, CO92 mutants pgm- pPst- and ΔyscN. Both completely protected BALB/c mice against subcutaneous and aerosol challenge with Y. pestis. Strain CD-1 outbred mice were more resistant to bubonic (but not pneumonic) plague than BALB/c mice, but the vaccines elicited partial protection of CD-1 mice against aerosol challenge, while providing full protection against subcutaneous challenge. A ΔyscN mutant of the nonencapsulated C12 strain was expected to display antigens previously concealed by the capsule. C12 ΔyscN elicited negligible titers to F1 but comparable antibody levels to whole killed bacteria, as did CO92 ΔyscN. Although one dose of C12 ΔyscN was not protective, vaccination with two doses of either CO92 ΔyscN, or a combination of the ΔyscN mutants of C12 and CO92, protected optimally against lethal bubonic or pneumonic plague. Protection against encapsulated Y. pestis required inclusion of F1 in the vaccine and was associated with high anti-F1 titers.
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Trevino SR, Dankmeyer JL, Fetterer DP, Klimko CP, Raymond JLW, Moreau AM, Soffler C, Waag DM, Worsham PL, Amemiya K, Ruiz SI, Cote CK, Krakauer T. Comparative virulence of three different strains of Burkholderia pseudomallei in an aerosol non-human primate model. PLoS Negl Trop Dis 2021; 15:e0009125. [PMID: 33571211 PMCID: PMC7904162 DOI: 10.1371/journal.pntd.0009125] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 02/24/2021] [Accepted: 01/11/2021] [Indexed: 01/19/2023] Open
Abstract
Melioidosis, caused by the Gram-negative bacterium Burkholderia pseudomallei, is a major cause of sepsis and mortality in endemic regions of Southeast Asia and Northern Australia. B. pseudomallei is a potential bioterrorism agent due to its high infectivity, especially via inhalation, and its inherent resistance to antimicrobials. There is currently no vaccine for melioidosis and antibiotic treatment can fail due to innate drug resistance, delayed diagnosis and treatment, or insufficient duration of treatment. A well-characterized animal model that mimics human melioidosis is needed for the development of new medical countermeasures. This study first characterized the disease progression of melioidosis in the African green monkey (AGM) and rhesus macaque (RM) for non-human primate model down-selection. All AGMs developed acute lethal disease similar to that described in human acute infection following exposure to aerosolized B. pseudomallei strain HBPUB10134a. Only 20% of RMs succumbed to acute disease. Disease progression, immune response and pathology of two other strains of B. pseudomallei, K96243 and MSHR5855, were also compared using AGMs. These three B. pseudomallei strains represent a highly virulent strain from Thailand (HBPUB101034a), a highly virulent strains from Australia (MSHR5855), and a commonly used laboratory strains originating from Thailand (K96243). Animals were observed for clinical signs of infection and blood samples were analyzed for cytokine responses, blood chemistry and leukocyte changes in order to characterize bacterial infection. AGMs experienced fever after exposure to aerosolized B. pseudomallei at the onset of acute disease. Inflammation, abscesses and/or pyogranulomas were observed in lung with all three strains of B. pseudomallei. Inflammation, abscesses and/or pyogranulomas were observed in lymph nodes, spleen, liver and/or kidney with B. pseudomallei, HBPUB10134a and K96243. Additionally, the Australian strain MSHR5855 induced brain lesions in one AGM similar to clinical cases of melioidosis seen in Australia. Elevated serum levels of IL-1β, IL-1 receptor antagonist, IL-6, MCP-1, G-CSF, HGF, IFNγ, MIG, I-TAC, and MIP-1β at terminal end points can be significantly correlated with non-survivors with B. pseudomallei infection in AGM. The AGM model represents an acute model of B. pseudomallei infection for all three strains from two geographical locations and will be useful for efficacy testing of vaccines and therapeutics against melioidosis. In summary, a dysregulated immune response leading to excessive persistent inflammation and inflammatory cell death is the key driver of acute melioidosis. Early intervention in these pathways will be necessary to counter B. pseudomallei and mitigate the pathological consequences of melioidosis. Melioidosis, caused by the Gram-negative bacterium Burkholderia pseudomallei, is endemic in tropical regions globally and is an emerging threat in non-tropical areas worldwide. Its mortality rate is high in endemic areas due to its high infectivity, antimicrobial resistance, lack of available vaccines and limited treatment options. Animal model development and pathogenicity studies of various isolates are critical for the development of countermeasures against this pathogen. In this study, we compared the virulence of three different isolates of B. pseudomallei from two geographical locations in an aerosol non-human primate model. We found that early elevations of both pro-inflammatory and anti-inflammatory mediators, as well as the persistence of these mediators in the terminal phase of bacterial infection correlate with mortality. Histopathological analysis showed that the severity of lesions in various organs also correlates with the virulence of the B. pseudomallei strains, HBPUB10134a, MSHR5855 and K96243. Thus, a dysregulated immune response leading to excessive IL-1β and IL-6 at terminal end points and necrosis are key drivers of acute melioidosis. Development of drugs targeting these host response processes will be necessary to counter B. pseudomallei and mitigate the pathological consequences of melioidosis. This non-human primate model will facilitate the screening of vaccines and novel therapeutics.
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Affiliation(s)
- Sylvia R. Trevino
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
| | - Jennifer L. Dankmeyer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
| | - David P. Fetterer
- Biostatistics Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
| | - Christopher P. Klimko
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
| | - Jo Lynne W. Raymond
- Pathology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
| | - Alicia M. Moreau
- Pathology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
| | - Carl Soffler
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
| | - David M. Waag
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
| | - Patricia L. Worsham
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
| | - Kei Amemiya
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
| | - Sara I. Ruiz
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
| | - Christopher K. Cote
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
- * E-mail: (CKC); (TK)
| | - Teresa Krakauer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
- * E-mail: (CKC); (TK)
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Amemiya K, Zeng X, Bearss JJ, Cote CK, Soffler C, Bernhards RC, Dankmeyer JL, Ribot WJ, Trevino SR, Welkos SL, Worsham PL, Waag DM. Laser Scanning Confocal Microscopy Was Used to Validate the Presence of Burkholderia Pseudomallei or B. Mallei in Formalin-Fixed Paraffin Embedded Tissues. Trop Med Infect Dis 2020; 5:tropicalmed5020065. [PMID: 32365605 PMCID: PMC7345562 DOI: 10.3390/tropicalmed5020065] [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: 03/23/2020] [Revised: 04/18/2020] [Accepted: 04/20/2020] [Indexed: 11/17/2022] Open
Abstract
Burkholderia pseudomallei and B. mallei are Gram-negative, facultative intracellular bacteria that cause melioidosis and glanders, respectively. Currently, there are no vaccines for these two diseases. Animal models have been developed to evaluate vaccines and therapeutics. Tissues from infected animals, however, must be fixed in formalin and embedded in paraffin (FFPE) before analysis. A brownish staining material in infected tissues that represents the exopolysaccharide of the pathogen was seen by bright field microscopy but not the actual microorganism. Because of these results, FFPE tissue was examined by laser scanning confocal microscopy (LSCM) in an attempt to see the microorganism. Archival FFPE tissues were examined from ten mice, and five nonhuman primates after exposure to B. pseudomallei or B.mallei by LSCM. Additionally, a historical spleen biopsy from a human suspected of exposure to B. mallei was examined. B. pseudomallei was seen in many of the infected tissues from mice. Four out of five nonhuman primates were positive for the pathogen. In the human sample, B. mallei was seen in pyogranulomas in the spleen biopsy. Thus, the presence of the pathogen was validated by LSCM in murine, nonhuman primate, and human FFPE tissues.
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Affiliation(s)
- Kei Amemiya
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702, USA; (C.K.C.); (C.S.); (J.L.D.); (W.J.R.); (S.R.T.); (S.L.W.); (P.L.W.); (D.M.W.)
- Correspondence: ; Tel.: +1-301-619-2182
| | - Xiankun Zeng
- Pathology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702, USA; (X.Z.); (J.J.B.)
| | - Jeremy J. Bearss
- Pathology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702, USA; (X.Z.); (J.J.B.)
| | - Christopher K. Cote
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702, USA; (C.K.C.); (C.S.); (J.L.D.); (W.J.R.); (S.R.T.); (S.L.W.); (P.L.W.); (D.M.W.)
| | - Carl Soffler
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702, USA; (C.K.C.); (C.S.); (J.L.D.); (W.J.R.); (S.R.T.); (S.L.W.); (P.L.W.); (D.M.W.)
| | - Robert C. Bernhards
- U.S. Army Combat Capabilities Development Command Chemical Biological Center, 8198 Blackhawk Road, Aberdeen Proving Ground, MD 21010, USA;
| | - Jennifer L. Dankmeyer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702, USA; (C.K.C.); (C.S.); (J.L.D.); (W.J.R.); (S.R.T.); (S.L.W.); (P.L.W.); (D.M.W.)
| | - Wilson J. Ribot
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702, USA; (C.K.C.); (C.S.); (J.L.D.); (W.J.R.); (S.R.T.); (S.L.W.); (P.L.W.); (D.M.W.)
| | - Sylvia R. Trevino
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702, USA; (C.K.C.); (C.S.); (J.L.D.); (W.J.R.); (S.R.T.); (S.L.W.); (P.L.W.); (D.M.W.)
| | - Susan L. Welkos
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702, USA; (C.K.C.); (C.S.); (J.L.D.); (W.J.R.); (S.R.T.); (S.L.W.); (P.L.W.); (D.M.W.)
| | - Patricia L. Worsham
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702, USA; (C.K.C.); (C.S.); (J.L.D.); (W.J.R.); (S.R.T.); (S.L.W.); (P.L.W.); (D.M.W.)
| | - David M. Waag
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702, USA; (C.K.C.); (C.S.); (J.L.D.); (W.J.R.); (S.R.T.); (S.L.W.); (P.L.W.); (D.M.W.)
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10
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The Impact of Age and Sex on Mouse Models of Melioidosis. Pathogens 2020; 9:pathogens9020113. [PMID: 32054106 PMCID: PMC7168040 DOI: 10.3390/pathogens9020113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 01/29/2020] [Accepted: 02/04/2020] [Indexed: 12/15/2022] Open
Abstract
Mouse models have been used to generate critical data for many infectious diseases. In the case of Burkholderia pseudomallei, mouse models have been invaluable for bacterial pathogenesis studies as well as for testing novel medical countermeasures including both vaccines and therapeutics. Mouse models of melioidosis have also provided a possible way forward to better understand the chronicity associated with this infection, as it appears that BALB/c mice develop an acute infection with B. pseudomallei, whereas the C57BL/6 model is potentially more suggestive of a chronic infection. Several unanswered questions, however, persist around this model. In particular, little attention has been paid to the effect of age or sex on the disease outcome in these animal models. In this report, we determined the LD50 of the B. pseudomallei K96243 strain in both female and male BALB/c and C57BL/6 mice in three distinct age groups. Our data demonstrated a modest increase in susceptibility associated with sex in this model, and we documented important histopathological differences associated with the reproductive systems of each sex. There was a statistically significant inverse correlation between age and susceptibility. The older mice, in most cases, were more susceptible to the infection. Additionally, our retrospective analyses suggested that the impact of animal supplier on disease outcome in mice may be minimal. These observations were consistent regardless of whether the mice were injected with bacteria intraperitoneally or if they were exposed to aerosolized bacteria. All of these factors should be considered when designing experiments using mouse models of melioidosis.
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Amemiya K, Dankmeyer JL, Bearss JJ, Zeng X, Stonier SW, Soffler C, Cote CK, Welkos SL, Fetterer DP, Chance TB, Trevino SR, Worsham PL, Waag DM. Dysregulation of TNF-α and IFN-γ expression is a common host immune response in a chronically infected mouse model of melioidosis when comparing multiple human strains of Burkholderia pseudomallei. BMC Immunol 2020; 21:5. [PMID: 32013893 PMCID: PMC6998218 DOI: 10.1186/s12865-020-0333-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 01/13/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Melioidosis is endemic in Southeast Asia and Northern Australia and is caused by the Gram-negative, facultative intracellular pathogen Burkholderia pseudomallei. Diagnosis of melioidosis is often difficult because of the protean clinical presentation of the disease, and it may mimic other diseases, such as tuberculosis. There are many different strains of B. pseudomallei that have been isolated from patients with melioidosis, but it was not clear if they could cause a similar disease in a chronic BALB/c murine model of melioidosis. Hence, we wanted to examine chronically infected mice exposed to different strains of B. pseudomallei to determine if there were differences in the host immune response to the pathogen. RESULTS We identified common host immune responses exhibited in chronically infected BALB/c mice, although there was some heterogeneity in the host response in chronically infected mice after exposure to different strains of B. pseudomallei. They all displayed pyogranulomatous lesions in their spleens with a large influx of monocytes/macrophages, NK cells, and neutrophils identified by flow cytometry. Sera from chronically infected mice by ELISA exhibited elevated IgG titers to the pathogen, and we detected by Luminex micro-bead array technology a significant increase in the expression of inflammatory cytokines/chemokines, such as IFN-γ, IL-1α, IL-1β, KC, and MIG. By immunohistochemical and in situ RNA hybridization analysis we found that the increased expression of proinflammatory cytokines (IL-1α, IL-1β, TNF-α, IFN-γ) was confined primarily to the area with the pathogen within pyogranulomatous lesions. We also found that cultured splenocytes from chronically infected mice could express IFN-γ, TNF-α, and MIP-1α ex vivo without the need for additional exogenous stimulation. In addition by flow cytometry, we detected significant amounts of intracellular expression of TNF-α and IFN-γ without a protein transport blocker in monocytes/macrophages, NK cells, and neutrophils but not in CD4+ or CD8+ T cells in splenocytes from chronically infected mice. CONCLUSION Taken together the common features we have identified in chronically infected mice when 10 different human clinical strains of B. pseudomallei were examined could serve as biomarkers when evaluating potential therapeutic agents in mice for the treatment of chronic melioidosis in humans.
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Affiliation(s)
- Kei Amemiya
- Bacteriology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, USA.
| | - Jennifer L Dankmeyer
- Bacteriology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, USA
| | - Jeremy J Bearss
- Pathology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, USA
| | - Xiankun Zeng
- Pathology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, USA
| | - Spencer W Stonier
- Virology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, USA
| | - Carl Soffler
- Bacteriology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, USA
| | - Christopher K Cote
- Bacteriology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, USA
| | - Susan L Welkos
- Bacteriology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, USA
| | - David P Fetterer
- Bacteriology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, USA
| | - Taylor B Chance
- Pathology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, USA
| | - Sylvia R Trevino
- Bacteriology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, USA
| | - Patricia L Worsham
- Bacteriology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, USA
| | - David M Waag
- Bacteriology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, USA
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12
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Amemiya K, Dankmeyer JL, Biryukov SS, Treviño SR, Klimko CP, Mou SM, Fetterer DP, Garnes PG, Cote CK, Worsham PL, DeShazer D. Deletion of Two Genes in Burkholderia pseudomallei MSHR668 That Target Essential Amino Acids Protect Acutely Infected BALB/c Mice and Promote Long Term Survival. Vaccines (Basel) 2019; 7:E196. [PMID: 31779073 PMCID: PMC6963190 DOI: 10.3390/vaccines7040196] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 10/31/2019] [Accepted: 11/15/2019] [Indexed: 12/25/2022] Open
Abstract
Melioidosis is an emerging disease that is caused by the facultative intracellular pathogen Burkholderia pseudomallei. It is intrinsically resistant to many antibiotics and host risk factors play a major role in susceptibility to infection. Currently, there is no human or animal vaccine against melioidosis. In this study, multiple B. pseudomallei MSHR668 deletion mutants were evaluated as live attenuated vaccines in the sensitive BALB/c mouse model of melioidosis. The most efficacious vaccines after an intraperitoneal challenge with 50-fold over the 50% median lethal dose (MLD50) with B. pseudomallei K96243 were 668 ΔhisF and 668 ΔilvI. Both vaccines completely protected mice in the acute phase of infection and showed significant protection (50% survivors) during the chronic phase of infection. The spleens of the survivors that were examined were sterile. Splenocytes from mice vaccinated with 668 ΔhisF and 668 ΔilvI expressed higher amounts of IFN-γ after stimulation with B. pseudomallei antigens than splenocytes from mice vaccinated with less protective candidates. Finally, we demonstrate that 668 ΔhisF is nonlethal in immunocompromised NOD/SCID mice. Our results show that 668 ΔhisF and 668 ΔilvI provide protective cell-mediated immune responses in the acute phase of infection and promote long term survival in the sensitive BALB/c mouse model of melioidosis.
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Affiliation(s)
- Kei Amemiya
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA; (K.A.); (J.L.D.); (S.S.B.); (S.R.T.); (C.P.K.); (S.M.M.); (C.K.C.); (P.L.W.)
| | - Jennifer L. Dankmeyer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA; (K.A.); (J.L.D.); (S.S.B.); (S.R.T.); (C.P.K.); (S.M.M.); (C.K.C.); (P.L.W.)
| | - Sergei S. Biryukov
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA; (K.A.); (J.L.D.); (S.S.B.); (S.R.T.); (C.P.K.); (S.M.M.); (C.K.C.); (P.L.W.)
| | - Sylvia R. Treviño
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA; (K.A.); (J.L.D.); (S.S.B.); (S.R.T.); (C.P.K.); (S.M.M.); (C.K.C.); (P.L.W.)
| | - Christopher P. Klimko
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA; (K.A.); (J.L.D.); (S.S.B.); (S.R.T.); (C.P.K.); (S.M.M.); (C.K.C.); (P.L.W.)
| | - Sherry M. Mou
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA; (K.A.); (J.L.D.); (S.S.B.); (S.R.T.); (C.P.K.); (S.M.M.); (C.K.C.); (P.L.W.)
| | - David P. Fetterer
- Biostatistical Services, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA; (D.P.F.); (P.G.G.)
| | - Preston G. Garnes
- Biostatistical Services, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA; (D.P.F.); (P.G.G.)
| | - Christopher K. Cote
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA; (K.A.); (J.L.D.); (S.S.B.); (S.R.T.); (C.P.K.); (S.M.M.); (C.K.C.); (P.L.W.)
| | - Patricia L. Worsham
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA; (K.A.); (J.L.D.); (S.S.B.); (S.R.T.); (C.P.K.); (S.M.M.); (C.K.C.); (P.L.W.)
| | - David DeShazer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA; (K.A.); (J.L.D.); (S.S.B.); (S.R.T.); (C.P.K.); (S.M.M.); (C.K.C.); (P.L.W.)
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13
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Funnell SGP, Tree JA, Hatch GJ, Bate SR, Hall G, Pearson G, Rayner EL, Roberts ADG, Vipond J. Dose-dependant acute or subacute disease caused by Burkholderia pseudomallei strain NCTC 13392 in a BALB/c aerosol model of infection. J Appl Microbiol 2019; 127:1224-1235. [PMID: 31330088 PMCID: PMC6747009 DOI: 10.1111/jam.14396] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 06/21/2019] [Accepted: 06/25/2019] [Indexed: 01/26/2023]
Abstract
AIMS The goal of this study was to examine, for the first time, the virulence and pathogenicity of aerosolized Burkholderia pseudomallei, strain NCTC 13392, in BALB/c mice in order to develop an animal model for testing novel medical countermeasures (MCMs) for the treatment of human acute and subacute (a disease state between acute and chronic) melioidosis. METHODS AND RESULTS BALB/c mice were exposed to varying doses of aerosolized bacteria. Acute disease was seen in animals exposed to a very-high dose (≥103 CFU per animal) and death occurred 3-4 days postchallenge (pc). Bacteria were detected in the lungs, liver, kidney and spleen. In contrast, animals exposed to a low dose (<10 CFU per animal) survived to the end of the study (day 30 pc) but developed weight loss, a bacterial tissue burden and increasing clinical signs of infection from day 20 pc onwards, mimicking a subacute form of the disease. Pathological changes in the tissues mirrored these findings. CONCLUSIONS This proof of concept study has shown that B. pseudomallei strain NCTC 13392 is virulent and pathogenic in BALB/c mice, when delivered by aerosol. By varying the doses of aerosolized bacteria it was possible to mimic characteristics of both human acute and subacute melioidosis, at the same time, within the same study. SIGNIFICANCE AND IMPACT OF THE STUDY Burkholderia pseudomallei, the aetiological agent of melioidosis, causes a serious and often fatal disease in humans and animals. Novel MCMs are urgently needed for both public health and biodefense purposes. The present model provides a useful tool for the assessment and evaluation of new MCMs (e.g. therapeutics and vaccines) and offers the potential for testing new treatments for both subacute to chronic and acute melioidosis prior to human clinical trials.
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Affiliation(s)
- S G P Funnell
- National Infection Service, Public Health England (PHE), Salisbury, Wiltshire, UK
| | - J A Tree
- National Infection Service, Public Health England (PHE), Salisbury, Wiltshire, UK
| | - G J Hatch
- National Infection Service, Public Health England (PHE), Salisbury, Wiltshire, UK
| | - S R Bate
- National Infection Service, Public Health England (PHE), Salisbury, Wiltshire, UK
| | - G Hall
- National Infection Service, Public Health England (PHE), Salisbury, Wiltshire, UK
| | - G Pearson
- National Infection Service, Public Health England (PHE), Salisbury, Wiltshire, UK
| | - E L Rayner
- National Infection Service, Public Health England (PHE), Salisbury, Wiltshire, UK
| | - A D G Roberts
- National Infection Service, Public Health England (PHE), Salisbury, Wiltshire, UK
| | - J Vipond
- National Infection Service, Public Health England (PHE), Salisbury, Wiltshire, UK
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14
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Bachert BA, Biryukov SS, Chua J, Rodriguez SA, Toothman RG, Cote CK, Klimko CP, Hunter M, Shoe JL, Williams JA, Kuehl KA, Biot FV, Bozue JA. A Francisella novicida Mutant, Lacking the Soluble Lytic Transglycosylase Slt, Exhibits Defects in Both Growth and Virulence. Front Microbiol 2019; 10:1343. [PMID: 31258523 PMCID: PMC6587636 DOI: 10.3389/fmicb.2019.01343] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 05/29/2019] [Indexed: 01/28/2023] Open
Abstract
Francisella tularensis is the causative agent of tularemia and has gained recent interest as it poses a significant biothreat risk. F. novicida is commonly used as a laboratory surrogate for tularemia research due to genetic similarity and susceptibility of mice to infection. Currently, there is no FDA-approved tularemia vaccine, and identifying therapeutic targets remains a critical gap in strategies for combating this pathogen. Here, we investigate the soluble lytic transglycosylase or Slt in F. novicida, which belongs to a class of peptidoglycan-modifying enzymes known to be involved in cell division. We assess the role of Slt in biology and virulence of the organism as well as the vaccine potential of the slt mutant. We show that the F. novicida slt mutant has a significant growth defect in acidic pH conditions. Further microscopic analysis revealed significantly altered cell morphology compared to wild-type, including larger cell size, extensive membrane protrusions, and cell clumping and fusion, which was partially restored by growth in neutral pH or genetic complementation. Viability of the mutant was also significantly decreased during growth in acidic medium, but not at neutral pH. Furthermore, the slt mutant exhibited significant attenuation in a murine model of intranasal infection and virulence could be restored by genetic complementation. Moreover, we could protect mice using the slt mutant as a live vaccine strain against challenge with the parent strain; however, we were not able to protect against challenge with the fully virulent F. tularensis Schu S4 strain. These studies demonstrate a critical role for the Slt enzyme in maintaining proper cell division and morphology in acidic conditions, as well as replication and virulence in vivo. Our results suggest that although the current vaccination strategy with F. novicida slt mutant would not protect against Schu S4 challenges, the Slt enzyme could be an ideal target for future therapeutic development.
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Affiliation(s)
- Beth A Bachert
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States
| | - Sergei S Biryukov
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States
| | - Jennifer Chua
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States
| | - Sabrina A Rodriguez
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States
| | - Ronald G Toothman
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States
| | - Christopher K Cote
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States
| | - Christopher P Klimko
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States
| | - Melissa Hunter
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States
| | - Jennifer L Shoe
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States
| | - Janice A Williams
- Pathology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States
| | - Kathleen A Kuehl
- Pathology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States
| | - Fabrice V Biot
- Unité de Bactériologie/UMR_MD1, Département de Biologie des Agents Transmissibles, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France
| | - Joel A Bozue
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States
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