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Debowski AW, Bzdyl NM, Thomas DR, Scott NE, Jenkins CH, Iwasaki J, Kibble EA, Khoo CA, Scheuplein NJ, Seibel PM, Lohr T, Metters G, Bond CS, Norville IH, Stubbs KA, Harmer NJ, Holzgrabe U, Newton HJ, Sarkar-Tyson M. Macrophage infectivity potentiator protein, a peptidyl prolyl cis-trans isomerase, essential for Coxiella burnetii growth and pathogenesis. PLoS Pathog 2023; 19:e1011491. [PMID: 37399210 DOI: 10.1371/journal.ppat.1011491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 06/14/2023] [Indexed: 07/05/2023] Open
Abstract
Coxiella burnetii is a Gram-negative intracellular pathogen that causes the debilitating disease Q fever, which affects both animals and humans. The only available human vaccine, Q-Vax, is effective but has a high risk of severe adverse reactions, limiting its use as a countermeasure to contain outbreaks. Therefore, it is essential to identify new drug targets to treat this infection. Macrophage infectivity potentiator (Mip) proteins catalyse the folding of proline-containing proteins through their peptidyl prolyl cis-trans isomerase (PPIase) activity and have been shown to play an important role in the virulence of several pathogenic bacteria. To date the role of the Mip protein in C. burnetii pathogenesis has not been investigated. This study demonstrates that CbMip is likely to be an essential protein in C. burnetii. The pipecolic acid derived compounds, SF235 and AN296, which have shown utility in targeting other Mip proteins from pathogenic bacteria, demonstrate inhibitory activities against CbMip. These compounds were found to significantly inhibit intracellular replication of C. burnetii in both HeLa and THP-1 cells. Furthermore, SF235 and AN296 were also found to exhibit antibiotic properties against both the virulent (Phase I) and avirulent (Phase II) forms of C. burnetii Nine Mile Strain in axenic culture. Comparative proteomics, in the presence of AN296, revealed alterations in stress responses with H2O2 sensitivity assays validating that Mip inhibition increases the sensitivity of C. burnetii to oxidative stress. In addition, SF235 and AN296 were effective in vivo and significantly improved the survival of Galleria mellonella infected with C. burnetii. These results suggest that unlike in other bacteria, Mip in C. burnetii is required for replication and that the development of more potent inhibitors against CbMip is warranted and offer potential as novel therapeutics against this pathogen.
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Affiliation(s)
- Aleksandra W Debowski
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, The University of Western Australia, Nedlands, Western Australia, Australia
- School of Molecular Sciences, The University of Western Australia, Crawley, Western Australia, Australia
| | - Nicole M Bzdyl
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, The University of Western Australia, Nedlands, Western Australia, Australia
| | - David R Thomas
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Australia
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Nichollas E Scott
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Australia
| | | | - Jua Iwasaki
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, The University of Western Australia, Nedlands, Western Australia, Australia
- Wesfarmers Centre for Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Nedlands, Western Australia, Australia
- Centre for Child Health Research, University of Western Australia, Perth, Western Australia, Australia
| | - Emily A Kibble
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, The University of Western Australia, Nedlands, Western Australia, Australia
- School of Veterinary and Life Sciences, Murdoch University, Perth, WA, Australia
- DMTC Limited, Level 1, Kew, Australia
| | - Chen Ai Khoo
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Australia
| | - Nicolas J Scheuplein
- Institute of Pharmacy and Food Chemistry, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Pamela M Seibel
- School of Molecular Sciences, The University of Western Australia, Crawley, Western Australia, Australia
| | - Theresa Lohr
- Institute of Pharmacy and Food Chemistry, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Georgie Metters
- Defence Science and Technology Laboratory, Porton Down, Salisbury, United Kingdom
- Department of Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, United Kingdom
| | - Charles S Bond
- School of Molecular Sciences, The University of Western Australia, Crawley, Western Australia, Australia
| | - Isobel H Norville
- Defence Science and Technology Laboratory, Porton Down, Salisbury, United Kingdom
- Department of Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, United Kingdom
| | - Keith A Stubbs
- School of Molecular Sciences, The University of Western Australia, Crawley, Western Australia, Australia
| | - Nicholas J Harmer
- Department of Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, United Kingdom
- Living Systems Institute, Stocker Road Exeter, United Kingdom
| | - Ulrike Holzgrabe
- Institute of Pharmacy and Food Chemistry, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Hayley J Newton
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Australia
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Mitali Sarkar-Tyson
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, The University of Western Australia, Nedlands, Western Australia, Australia
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2
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Cellular and molecular level host-pathogen interactions in Francisella tularensis: A microbial gene network study. Comput Biol Chem 2021; 96:107601. [PMID: 34801846 DOI: 10.1016/j.compbiolchem.2021.107601] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 08/12/2021] [Accepted: 11/09/2021] [Indexed: 01/17/2023]
Abstract
Due to the high infectivity and fatal effect on human population, Francisella tularensis (F. tularensis) is classified as a potential biological warfare agent. The interaction between host and pathogen behind the successful establishment of F. tularensis infection within the human host is largely unknown. In our present work, we have studied the molecular level interactions between the host cellular components and F. tularensis genes to understand the interplay between the host and pathogen. Interestingly, we have identified the pathways associated with the pathogen offensive strategies that help in invasion of host defensive systems. The F. tularensis genes purL, katG, proS, rpoB and fusA have displayed high number of interactions with the host genes and thus play a crucial role in vital pathogen pathways. The pathways identified were involved in adaptation to different stress conditions within the host and might be crucial for designing new therapeutic interventions against tularemia.
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Modi G, Marqus GM, Vippila MR, Gollapalli DR, Kim Y, Manna AC, Chacko S, Maltseva N, Wang X, Cullinane RT, Zhang Y, Kotler JLM, Kuzmic P, Zhang M, Lawson AP, Joachimiak A, Cheung A, Snider BB, Rothstein DM, Cuny GD, Hedstrom L. The Enzymatic Activity of Inosine 5'-Monophosphate Dehydrogenase May Not Be a Vulnerable Target for Staphylococcus aureus Infections. ACS Infect Dis 2021; 7:3062-3076. [PMID: 34590817 DOI: 10.1021/acsinfecdis.1c00342] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Many bacterial pathogens, including Staphylococcus aureus, require inosine 5'-monophosphate dehydrogenase (IMPDH) for infection, making this enzyme a promising new target for antibiotics. Although potent selective inhibitors of bacterial IMPDHs have been reported, relatively few have displayed antibacterial activity. Here we use structure-informed design to obtain inhibitors of S. aureus IMPDH (SaIMPDH) that have potent antibacterial activity (minimal inhibitory concentrations less than 2 μM) and low cytotoxicity in mammalian cells. The physicochemical properties of the most active compounds were within typical Lipinski/Veber space, suggesting that polarity is not a general requirement for achieving antibacterial activity. Five compounds failed to display activity in mouse models of septicemia and abscess infection. Inhibitor-resistant S. aureus strains readily emerged in vitro. Resistance resulted from substitutions in the cofactor/inhibitor binding site of SaIMPDH, confirming on-target antibacterial activity. These mutations decreased the binding of all inhibitors tested, but also decreased catalytic activity. Nonetheless, the resistant strains had comparable virulence to wild-type bacteria. Surprisingly, strains expressing catalytically inactive SaIMPDH displayed only a mild virulence defect. Collectively these observations question the vulnerability of the enzymatic activity of SaIMPDH as a target for the treatment of S. aureus infections, suggesting other functions of this protein may be responsible for its role in infection.
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Affiliation(s)
- Gyan Modi
- Department of Biology, Brandeis University, Waltham, Massachusetts 02453, United States
| | - Gary M. Marqus
- Graduate Program in Chemistry, Brandeis University, Waltham Massachusetts 02453, United States
| | - Mohana Rao Vippila
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Health Building 2, 4849 Calhoun Rd., Houston, Texas 77204, United States
| | | | - Youngchang Kim
- Center for Structural Genomics of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, Illinois 60667, United States
- The Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Adhar C. Manna
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755, United States
| | - Shibin Chacko
- Department of Biology, Brandeis University, Waltham, Massachusetts 02453, United States
| | - Natalia Maltseva
- Center for Structural Genomics of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, Illinois 60667, United States
- The Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Xingyou Wang
- Graduate Program in Chemistry, Brandeis University, Waltham Massachusetts 02453, United States
| | - Ryan T. Cullinane
- Department of Biochemistry, Brandeis University, Massachusetts 02453, United States
| | - Yubo Zhang
- Department of Biochemistry, Brandeis University, Massachusetts 02453, United States
| | - Judy L. M. Kotler
- Graduate Program in Biochemistry and Biophysics, Brandeis University, Waltham, Massachusetts 02453, United States
| | - Petr Kuzmic
- BioKin Ltd., Watertown, Massachusetts 02472, United States
| | - Minjia Zhang
- Department of Biology, Brandeis University, Waltham, Massachusetts 02453, United States
| | - Ann P. Lawson
- Department of Biology, Brandeis University, Waltham, Massachusetts 02453, United States
| | - Andrzej Joachimiak
- Center for Structural Genomics of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, Illinois 60667, United States
- The Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois 60367, United States
| | - Ambrose Cheung
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755, United States
| | - Barry B. Snider
- Department of Chemistry, Brandeis University, Waltham, Massachusetts 02453, United States
| | - David M. Rothstein
- David Rothstein Consulting, LLC, Lexington, Massachusetts 02421, United States
| | - Gregory D. Cuny
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Health Building 2, 4849 Calhoun Rd., Houston, Texas 77204, United States
| | - Lizbeth Hedstrom
- Department of Biology, Brandeis University, Waltham, Massachusetts 02453, United States
- Department of Chemistry, Brandeis University, Waltham, Massachusetts 02453, United States
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Deletion Mutants of Francisella Phagosomal Transporters FptA and FptF Are Highly Attenuated for Virulence and Are Protective Against Lethal Intranasal Francisella LVS Challenge in a Murine Model of Respiratory Tularemia. Pathogens 2021; 10:pathogens10070799. [PMID: 34202420 PMCID: PMC8308642 DOI: 10.3390/pathogens10070799] [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: 05/11/2021] [Revised: 06/09/2021] [Accepted: 06/17/2021] [Indexed: 11/17/2022] Open
Abstract
Francisella tularensis (Ft) is a Gram-negative, facultative intracellular bacterium that is a Tier 1 Select Agent of concern for biodefense for which there is no licensed vaccine. A subfamily of 9 Francisella phagosomal transporter (fpt) genes belonging to the Major Facilitator Superfamily of transporters was identified as critical to pathogenesis and potential targets for attenuation and vaccine development. We evaluated the attenuation and protective capacity of LVS derivatives with deletions of the fptA and fptF genes in the C57BL/6J mouse model of respiratory tularemia. LVSΔfptA and LVSΔfptF were highly attenuated with LD50 values of >20 times that of LVS when administered intranasally and conferred 100% protection against lethal challenge. Immune responses to the fpt mutant strains in mouse lungs on day 6 post-infection were substantially modified compared to LVS and were associated with reduced organ burdens and reduced pathology. The immune responses to LVSΔfptA and LVSΔfptF were characterized by decreased levels of IL-10 and IL-1β in the BALF versus LVS, and increased numbers of B cells, αβ and γδ T cells, NK cells, and DCs versus LVS. These results support a fundamental requirement for FptA and FptF in the pathogenesis of Ft and the modulation of the host immune response.
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Cunningham AL, Mann BJ, Qin A, Santiago AE, Grassel C, Lipsky M, Vogel SN, Barry EM. Characterization of Schu S4 aro mutants as live attenuated tularemia vaccine candidates. Virulence 2021; 11:283-294. [PMID: 32241221 PMCID: PMC7161688 DOI: 10.1080/21505594.2020.1746557] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
There is a need for development of an effective vaccine against Francisella tularensis, as this potential bioweapon has a high mortality rate and low infectious dose when delivered via the aerosol route. Moreover, this Tier 1 agent has a history of weaponization. We engineered targeted mutations in the Type A strain F. tularensis subspecies tularensis Schu S4 in aro genes encoding critical enzymes in aromatic amino acid biosynthesis. F. tularensis Schu S4ΔaroC, Schu S4ΔaroD, and Schu S4ΔaroCΔaroD mutant strains were attenuated for intracellular growth in vitro and for virulence in vivo and, conferred protection against pulmonary wild-type (WT) F. tularensis Schu S4 challenge in the C57BL/6 mouse model. F. tularensis Schu S4ΔaroD was identified as the most promising vaccine candidate, demonstrating protection against high-dose intranasal challenge; it protected against 1,000 CFU Schu S4, the highest level of protection tested to date. It also provided complete protection against challenge with 92 CFU of a F. tularensis subspecies holarctica strain (Type B). Mice responded to vaccination with Schu S4ΔaroD with systemic IgM and IgG2c, as well as the production of a functional T cell response as measured in the splenocyte-macrophage co-culture assay. This vaccine was further characterized for dissemination, histopathology, and cytokine/chemokine gene induction at defined time points following intranasal vaccination which confirmed its attenuation compared to WT Schu S4. Cytokine, chemokine, and antibody induction patterns compared to wild-type Schu S4 distinguish protective vs. pathogenic responses to F. tularensis and elucidate correlates of protection associated with vaccination against this agent.
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Affiliation(s)
| | - Barbara J Mann
- Department of Medicine, Division of Infectious Diseases and International Heath, University of Virginia, Charlottesville, VA, USA
| | - Aiping Qin
- Department of Medicine, Division of Infectious Diseases and International Heath, University of Virginia, Charlottesville, VA, USA
| | - Araceli E Santiago
- Department of Pediatrics, University of Virginia, Charlottesville, VA, USA
| | - Christen Grassel
- Center for Vaccine Development, University of Maryland Baltimore, Baltimore, MD, USA
| | - Michael Lipsky
- Department of Pathology, University of Maryland Baltimore, Baltimore, MD, USA
| | - Stefanie N Vogel
- Department of Microbiology and Immunology, University of Maryland Baltimore, Baltimore, MD, USA
| | - Eileen M Barry
- Center for Vaccine Development, University of Maryland Baltimore, Baltimore, MD, USA
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6
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O’Malley KJ, Bowling JL, Stinson E, Cole KS, Mann BJ, Namjoshi P, Hazlett KRO, Barry EM, Reed DS. Aerosol prime-boost vaccination provides strong protection in outbred rabbits against virulent type A Francisella tularensis. PLoS One 2018; 13:e0205928. [PMID: 30346998 PMCID: PMC6197691 DOI: 10.1371/journal.pone.0205928] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 10/03/2018] [Indexed: 12/15/2022] Open
Abstract
Tularemia, also known as rabbit fever, is a severe zoonotic disease in humans caused by the gram-negative bacterium Francisella tularensis (Ft). While there have been a number of attempts to develop a vaccine for Ft, few candidates have advanced beyond experiments in inbred mice. We report here that a prime-boost strategy with aerosol delivery of recombinant live attenuated candidate Ft S4ΔaroD offers significant protection (83% survival) in an outbred animal model, New Zealand White rabbits, against aerosol challenge with 248 cfu (11 LD50) of virulent type A Ft SCHU S4. Surviving rabbits given two doses of the attenuated strains by aerosol did not exhibit substantial post-challenge fevers, changes in erythrocyte sedimentation rate or in complete blood counts. At a higher challenge dose (3,186 cfu; 139 LD50), protection was still good with 66% of S4ΔaroD-vaccinated rabbits surviving while 50% of S4ΔguaBA vaccinated rabbits also survived challenge. Pre-challenge plasma IgG titers against Ft SCHU S4 corresponded with survival time after challenge. Western blot analysis found that plasma antibody shifted from predominantly targeting Ft O-antigen after the prime vaccination to other antigens after the boost. These results demonstrate the superior protection conferred by a live attenuated derivative of virulent F. tularensis, particularly when given in an aerosol prime-boost regimen.
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Affiliation(s)
- Katherine J. O’Malley
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Jennifer L. Bowling
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Elizabeth Stinson
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Kelly S. Cole
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Barbara J. Mann
- Department of Medicine, Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA, United States of America
| | - Prachi Namjoshi
- Department for Immunology & Microbial Diseases, Albany Medical College, Albany, NY, United States of America
| | - Karsten R. O. Hazlett
- Department for Immunology & Microbial Diseases, Albany Medical College, Albany, NY, United States of America
| | - Eileen M. Barry
- Center for Vaccine Development, University of Maryland Baltimore, Baltimore, MD, United States of America
| | - Douglas S. Reed
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, United States of America
- * E-mail:
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Jia Q, Horwitz MA. Live Attenuated Tularemia Vaccines for Protection Against Respiratory Challenge With Virulent F. tularensis subsp. tularensis. Front Cell Infect Microbiol 2018; 8:154. [PMID: 29868510 PMCID: PMC5963219 DOI: 10.3389/fcimb.2018.00154] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 04/24/2018] [Indexed: 12/11/2022] Open
Abstract
Francisella tularensis is the causative agent of tularemia and a Tier I bioterrorism agent. In the 1900s, several vaccines were developed against tularemia including the killed "Foshay" vaccine, subunit vaccines comprising F. tularensis protein(s) or lipoproteins(s) in an adjuvant formulation, and the F. tularensis Live Vaccine Strain (LVS); none were licensed in the U.S.A. or European Union. The LVS vaccine retains toxicity in humans and animals-especially mice-but has demonstrated efficacy in humans, and thus serves as the current gold standard for vaccine efficacy studies. The U.S.A. 2001 anthrax bioterrorism attack spawned renewed interest in vaccines against potential biowarfare agents including F. tularensis. Since live attenuated-but not killed or subunit-vaccines have shown promising efficacy and since vaccine efficacy against respiratory challenge with less virulent subspecies holarctica or F. novicida, or against non-respiratory challenge with virulent subsp. tularensis (Type A) does not reliably predict vaccine efficacy against respiratory challenge with virulent subsp. tularensis, the route of transmission and species of greatest concern in a bioterrorist attack, in this review, we focus on live attenuated tularemia vaccine candidates tested against respiratory challenge with virulent Type A strains, including homologous vaccines derived from mutants of subsp. holarctica, F. novicida, and subsp. tularensis, and heterologous vaccines developed using viral or bacterial vectors to express F. tularensis immunoprotective antigens. We compare the virulence and efficacy of these vaccine candidates with that of LVS and discuss factors that can significantly impact the development and evaluation of live attenuated tularemia vaccines. Several vaccines meet what we would consider the minimum criteria for vaccines to go forward into clinical development-safety greater than LVS and efficacy at least as great as LVS, and of these, several meet the higher standard of having efficacy ≥LVS in the demanding mouse model of tularemia. These latter include LVS with deletions in purMCD, sodBFt , capB or wzy; LVS ΔcapB that also overexpresses Type VI Secretion System (T6SS) proteins; FSC200 with a deletion in clpB; the single deletional purMCD mutant of F. tularensis SCHU S4, and a heterologous prime-boost vaccine comprising LVS ΔcapB and Listeria monocytogenes expressing T6SS proteins.
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Affiliation(s)
- Qingmei Jia
- Division of Infectious Diseases, Department of Medicine, 37-121 Center for Health Sciences, School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Marcus A. Horwitz
- Division of Infectious Diseases, Department of Medicine, 37-121 Center for Health Sciences, School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
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Deletion of the Major Facilitator Superfamily Transporter fptB Alters Host Cell Interactions and Attenuates Virulence of Type A Francisella tularensis. Infect Immun 2018; 86:IAI.00832-17. [PMID: 29311235 PMCID: PMC5820938 DOI: 10.1128/iai.00832-17] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 12/22/2017] [Indexed: 12/12/2022] Open
Abstract
Francisella tularensis is a Gram-negative, facultative, intracellular coccobacillus that can infect a wide variety of hosts. In humans, F. tularensis causes the zoonosis tularemia following insect bites, ingestion, inhalation, and the handling of infected animals. The fact that a very small inoculum delivered by the aerosol route can cause severe disease, coupled with the possibility of its use as an aerosolized bioweapon, has led to the classification of Francisella tularensis as a category A select agent and has renewed interest in the formulation of a vaccine. To this end, we engineered a type A strain SchuS4 derivative containing a targeted deletion of the major facilitator superfamily (MFS) transporter fptB. Based on the attenuating capacity of this deletion in the F. tularensis LVS background, we hypothesized that the deletion of this transporter would alter the intracellular replication and cytokine induction of the type A strain and attenuate virulence in the stringent C57BL/6J mouse model. Here we demonstrate that the deletion of fptB significantly alters the intracellular life cycle of F. tularensis, attenuating intracellular replication in both cell line-derived and primary macrophages and inducing a novel cytosolic escape delay. Additionally, we observed prominent differences in the in vitro cytokine profiles in human macrophage-like cells. The mutant was highly attenuated in the C57BL/6J mouse model and provided partial protection against virulent type A F. tularensis challenge. These results indicate a fundamental necessity for this nutrient transporter in the timely progression of F. tularensis through its replication cycle and in pathogenesis.
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Benzoxazoles, Phthalazinones, and Arylurea-Based Compounds with IMP Dehydrogenase-Independent Antibacterial Activity against Francisella tularensis. Antimicrob Agents Chemother 2017; 61:AAC.00939-17. [PMID: 28739786 DOI: 10.1128/aac.00939-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 07/07/2017] [Indexed: 01/06/2023] Open
Abstract
Francisella tularensis is the causative agent of tularemia and a potential biowarfare agent. The virulence of F. tularensis is decreased by deletion of guaB, the gene encoding IMP dehydrogenase (IMPDH), suggesting that this enzyme is a target for antibacterial design. Here we report that F. tularensis growth is blocked by inhibitors of bacterial IMPDHs. Seventeen compounds from two different frameworks, designated the D and Q series, display antibacterial activities with MICs of <1 μM. These compounds are also active against intracellular infections. Surprisingly, antibacterial activity does not correlate with IMPDH inhibition. In addition, the presence of guanine does not affect the antibacterial activity of most compounds, nor does the deletion of guaB These observations suggest that antibacterial activity derives from inhibition of another target(s). Moreover, D compounds display antibacterial activity only against F. tularensis, suggesting the presence of a unique target or uptake mechanism. A ΔguaB mutant resistant to compound D73 contained a missense mutation (Gly45Cys) in nuoB, which encodes a subunit of bacterial complex I. Overexpression of the nuoB mutant conferred resistance to D73 in both wild-type and ΔguaB strains. This strain was not resistant to Q compounds, suggesting that a different off-target mechanism operates for these compounds. Several Q compounds are also effective against Mycobacterium tuberculosis, in which a second target has also been implicated, in addition to IMPDH. The fortuitous presence of multiple targets with overlapping structure-activity relationships presents an intriguing opportunity for the development of robust antibiotics that may avoid the emergence of resistance.
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Golovliov I, Lindgren H, Eneslätt K, Conlan W, Mosnier A, Henry T, Sjöstedt A. An In Vitro Co-culture Mouse Model Demonstrates Efficient Vaccine-Mediated Control of Francisella tularensis SCHU S4 and Identifies Nitric Oxide as a Predictor of Efficacy. Front Cell Infect Microbiol 2016; 6:152. [PMID: 27933275 PMCID: PMC5122580 DOI: 10.3389/fcimb.2016.00152] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Accepted: 11/01/2016] [Indexed: 11/13/2022] Open
Abstract
Francisella tularensis is a highly virulent intracellular bacterium and cell-mediated immunity is critical for protection, but mechanisms of protection against highly virulent variants, such as the prototypic strain F. tularensis strain SCHU S4, are poorly understood. To this end, we established a co-culture system, based on splenocytes from naïve, or immunized mice and in vitro infected bone marrow-derived macrophages that allowed assessment of mechanisms controlling infection with F. tularensis. We utilized the system to understand why the clpB gene deletion mutant, ΔclpB, of SCHU S4 shows superior efficacy as a vaccine in the mouse model as compared to the existing human vaccine, the live vaccine strain (LVS). Compared to naïve splenocytes, ΔclpB-, or LVS-immune splenocytes conferred very significant control of a SCHU S4 infection and the ΔclpB-immune splenocytes were superior to the LVS-immune splenocytes. Cultures with the ΔclpB-immune splenocytes also contained higher levels of IFN-γ, IL-17, and GM-CSF and nitric oxide, and T cells expressing combinations of IFN-γ, TNF-α, and IL-17, than did cultures with LVS-immune splenocytes. There was strong inverse correlation between bacterial replication and levels of nitrite, an end product of nitric oxide, and essentially no control was observed when BMDM from iNOS-/- mice were infected. Collectively, the co-culture model identified a critical role of nitric oxide for protection against a highly virulent strain of F. tularensis.
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Affiliation(s)
- Igor Golovliov
- Laboratory for Molecular Infection Medicine Sweden, Department of Clinical Microbiology, Clinical Bacteriology, and Umeå University Umeå, Sweden
| | - Helena Lindgren
- Laboratory for Molecular Infection Medicine Sweden, Department of Clinical Microbiology, Clinical Bacteriology, and Umeå University Umeå, Sweden
| | - Kjell Eneslätt
- Laboratory for Molecular Infection Medicine Sweden, Department of Clinical Microbiology, Clinical Bacteriology, and Umeå University Umeå, Sweden
| | - Wayne Conlan
- National Research Council Canada, Institute for Biological Sciences Ottawa, ON, Canada
| | - Amandine Mosnier
- Centre International de Recherche en Infectiologie, Institut national de la santé et de la recherche médicale, U1111 Lyon, France
| | - Thomas Henry
- Centre International de Recherche en Infectiologie, Institut national de la santé et de la recherche médicale, U1111 Lyon, France
| | - Anders Sjöstedt
- Laboratory for Molecular Infection Medicine Sweden, Department of Clinical Microbiology, Clinical Bacteriology, and Umeå University Umeå, Sweden
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Stinson E, Smith LP, Cole KS, Barry EM, Reed DS. Respiratory and oral vaccination improves protection conferred by the live vaccine strain against pneumonic tularemia in the rabbit model. Pathog Dis 2016; 74:ftw079. [PMID: 27511964 DOI: 10.1093/femspd/ftw079] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/04/2016] [Indexed: 01/19/2023] Open
Abstract
Tularemia is a severe, zoonotic disease caused by a gram-negative bacterium, Francisella tularensis We have previously shown that rabbits are a good model of human pneumonic tularemia when exposed to aerosols containing a virulent, type A strain, SCHU S4. We further demonstrated that the live vaccine strain (LVS), an attenuated type B strain, extended time to death when given by scarification. Oral or aerosol vaccination has been previously shown in humans to offer superior protection to parenteral vaccination against respiratory tularemia challenge. Both oral and aerosol vaccination with LVS were well tolerated in the rabbit with only minimal fever and no weight loss after inoculation. Plasma antibody titers against F. tularensis were higher in rabbits that were vaccinated by either oral or aerosol routes compared to scarification. Thirty days after vaccination, all rabbits were challenged with aerosolized SCHU S4. LVS given by scarification extended time to death compared to mock-vaccinated controls. One orally vaccinated rabbit did survive aerosol challenge, however, only aerosol vaccination extended time to death significantly compared to scarification. These results further demonstrate the utility of the rabbit model of pneumonic tularemia in replicating what has been reported in humans and macaques as well as demonstrating the utility of vaccination by oral and respiratory routes against an aerosol tularemia challenge.
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Affiliation(s)
- Elizabeth Stinson
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Le'Kneitah P Smith
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Kelly Stefano Cole
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Eileen M Barry
- Center for Vaccine Development, University of Maryland, Baltimore, MD 21201, USA
| | - Douglas S Reed
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA 15260, USA
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Abstract
Francisella tularensis is the causative agent of the potentially lethal disease tularemia. Due to a low infectious dose and ease of airborne transmission, Francisella is classified as a category A biological agent. Despite the possible risk to public health, there is no safe and fully licensed vaccine. A potential vaccine candidate, an attenuated live vaccine strain, does not fulfil the criteria for general use. In this review, we will summarize existing and new candidates for live attenuated and subunit vaccines.
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13
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Roulis E, Bachmann N, Humphrys M, Myers G, Huston W, Polkinghorne A, Timms P. Phylogenetic analysis of human Chlamydia pneumoniae strains reveals a distinct Australian indigenous clade that predates European exploration of the continent. BMC Genomics 2015; 16:1094. [PMID: 26694618 PMCID: PMC4687280 DOI: 10.1186/s12864-015-2281-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 12/08/2015] [Indexed: 12/05/2022] Open
Abstract
Background The obligate intracellular bacterium Chlamydia pneumoniae is a common respiratory pathogen, which has been found in a range of hosts including humans, marsupials and amphibians. Whole genome comparisons of human C. pneumoniae have previously highlighted a highly conserved nucleotide sequence, with minor but key polymorphisms and additional coding capacity when human and animal strains are compared. Results In this study, we sequenced three Australian human C. pneumoniae strains, two of which were isolated from patients in remote indigenous communities, and compared them to all available C. pneumoniae genomes. Our study demonstrated a phylogenetically distinct human C. pneumoniae clade containing the two indigenous Australian strains, with estimates that the most recent common ancestor of these strains predates the arrival of European settlers to Australia. We describe several polymorphisms characteristic to these strains, some of which are similar in sequence to animal C. pneumoniae strains, as well as evidence to suggest that several recombination events have shaped these distinct strains. Conclusions Our study reveals a greater sequence diversity amongst both human and animal C. pneumoniae strains, and suggests that a wider range of strains may be circulating in the human population than current sampling indicates.
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Affiliation(s)
- Eileen Roulis
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, QLD, Australia.
| | - Nathan Bachmann
- Centre for Animal Health Innovation, Faculty of Science, Health, Education & Engineering, University of the Sunshine Coast, Sippy Downs, QLD, Australia.
| | - Michael Humphrys
- Institute for Genomic Sciences, University of Maryland, Baltimore, MD, USA.
| | - Garry Myers
- i3 Institute, University of Technology, Sydney, NSW, Australia.
| | - Wilhelmina Huston
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, QLD, Australia. .,i3 Institute, University of Technology, Sydney, NSW, Australia.
| | - Adam Polkinghorne
- Centre for Animal Health Innovation, Faculty of Science, Health, Education & Engineering, University of the Sunshine Coast, Sippy Downs, QLD, Australia.
| | - Peter Timms
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, QLD, Australia. .,Centre for Animal Health Innovation, Faculty of Science, Health, Education & Engineering, University of the Sunshine Coast, Sippy Downs, QLD, Australia.
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