1
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Weller SA, Armstrong SR, Bailey S, Burnell HT, Burt EL, Cant NE, Cawthorne KR, Chester M, Choules JE, Coe NA, Coward L, Cox VL, Emery ER, Evans CP, Finn A, Halford CM, Hamblin KA, Harrison GV, Hartley MG, Hudson C, James B, Jones HE, Keyser E, Lonsdale CL, Marshall LE, Maule CE, Miles JA, Newstead SL, Nicholls M, Osborne C, Pearcy AS, Penny LD, Perrot R, Rachwal P, Robinson V, Rushton D, Stahl FM, Staplehurst SV, Stapleton HL, Steeds K, Stephenson K, Thompson IJ, Thwaite JE, Ulaeto DO, Waters N, Wills DJ, Wills ZS, Rees C, Hutley EJ. Development and operation of the defence COVID-19 lab as a SARS-CoV-2 diagnostic screening capability for UK military personnel. BMJ Mil Health 2022; 170:e002134. [PMID: 35878971 PMCID: PMC10958320 DOI: 10.1136/military-2022-002134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 07/03/2022] [Indexed: 11/03/2022]
Abstract
BACKGROUND In the face of the COVID-19 pandemic, the Defence Science and Technology Laboratory (Dstl) and Defence Pathology combined to form the Defence Clinical Lab (DCL), an accredited (ISO/IEC 17025:2017) high-throughput SARS-CoV-2 PCR screening capability for military personnel. LABORATORY STRUCTURE AND RESOURCE The DCL was modular in organisation, with laboratory modules and supporting functions combining to provide the accredited SARS-CoV-2 (envelope (E)-gene) PCR assay. The DCL was resourced by Dstl scientists and military clinicians and biomedical scientists. LABORATORY RESULTS Over 12 months of operation, the DCL was open on 289 days and tested over 72 000 samples. Six hundred military SARS-CoV-2-positive results were reported with a median E-gene quantitation cycle (Cq) value of 30.44. The lowest Cq value for a positive result observed was 11.20. Only 64 samples (0.09%) were voided due to assay inhibition after processing started. CONCLUSIONS Through a sustained effort and despite various operational issues, the collaboration between Dstl scientific expertise and Defence Pathology clinical expertise provided the UK military with an accredited high-throughput SARS-CoV-2 PCR test capability at the height of the COVID-19 pandemic. The DCL helped facilitate military training and operational deployments contributing to the maintenance of UK military capability. In offering a bespoke capability, including features such as testing samples in unit batches and oversight by military consultant microbiologists, the DCL provided additional benefits to the UK Ministry of Defence that were potentially not available from other SARS-CoV-2 PCR laboratories. The links between Dstl and Defence Pathology have also been strengthened, benefitting future research activities and operational responses.
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Affiliation(s)
- Simon A Weller
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - S R Armstrong
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - S Bailey
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - H T Burnell
- Operations Division, Defence Science and Technology Laboratory, Porton Down, Salisbury, UK
| | - E L Burt
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - N E Cant
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - K R Cawthorne
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - M Chester
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - J E Choules
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - N A Coe
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - L Coward
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - V L Cox
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - E R Emery
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - C P Evans
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - A Finn
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - C M Halford
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - K A Hamblin
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - G V Harrison
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - M G Hartley
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - C Hudson
- Defence Pathology, Royal Centre for Defence Medicine, Birmingham, UK
| | - B James
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - H E Jones
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - E Keyser
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - C L Lonsdale
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - L E Marshall
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - C E Maule
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - J A Miles
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - S L Newstead
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - M Nicholls
- Defence Pathology, Royal Centre for Defence Medicine, Birmingham, UK
| | - C Osborne
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - A S Pearcy
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - L D Penny
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - R Perrot
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - P Rachwal
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - V Robinson
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - D Rushton
- Platform Systems Division, Defence Science and Technology Laboratory, Porton Down, Salisbury, UK
| | - F M Stahl
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - S V Staplehurst
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - H L Stapleton
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - K Steeds
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - K Stephenson
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - I J Thompson
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - J E Thwaite
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - D O Ulaeto
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - N Waters
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - D J Wills
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - Z S Wills
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - C Rees
- CBR Division, Defence Science and Technology Laboratory Porton Down, Salisbury, UK
| | - E J Hutley
- Defence Pathology, Royal Centre for Defence Medicine, Birmingham, UK
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2
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Thom RE, Eastaugh LS, O'Brien LM, Ulaeto DO, Findlay JS, Smither SJ, Phelps AL, Stapleton HL, Hamblin KA, Weller SA. Corrigendum: Evaluation of the SARS-CoV-2 Inactivation Efficacy Associated With Buffers From Three Kits Used on High-Throughput RNA Extraction Platforms. Front Cell Infect Microbiol 2021; 11:813442. [PMID: 34956936 PMCID: PMC8694096 DOI: 10.3389/fcimb.2021.813442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 11/23/2021] [Indexed: 11/22/2022] Open
Affiliation(s)
- Ruth E Thom
- CBR Division, Dstl Porton Down, Salisbury, United Kingdom
| | - Lin S Eastaugh
- CBR Division, Dstl Porton Down, Salisbury, United Kingdom
| | - Lyn M O'Brien
- CBR Division, Dstl Porton Down, Salisbury, United Kingdom
| | - David O Ulaeto
- CBR Division, Dstl Porton Down, Salisbury, United Kingdom
| | | | | | | | | | | | - Simon A Weller
- CBR Division, Dstl Porton Down, Salisbury, United Kingdom
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3
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Thom RE, Eastaugh LS, O'Brien LM, Ulaeto DO, Findlay JS, Smither SJ, Phelps AL, Stapleton HL, Hamblin KA, Weller SA. Evaluation of the SARS-CoV-2 Inactivation Efficacy Associated With Buffers From Three Kits Used on High-Throughput RNA Extraction Platforms. Front Cell Infect Microbiol 2021; 11:716436. [PMID: 34604108 PMCID: PMC8481894 DOI: 10.3389/fcimb.2021.716436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 08/20/2021] [Indexed: 12/14/2022] Open
Abstract
Rapid and demonstrable inactivation of SARS-CoV-2 is crucial to ensure operator safety during high-throughput testing of clinical samples. The inactivation efficacy of SARS-CoV-2 was evaluated using commercially available lysis buffers from three viral RNA extraction kits used on two high-throughput (96-well) RNA extraction platforms (Qiagen QIAcube HT and the Thermo Fisher KingFisher Flex) in combination with thermal treatment. Buffer volumes and sample ratios were chosen for their optimised suitability for RNA extraction rather than inactivation efficacy and tested against a representative sample type: SARS-CoV-2 spiked into viral transport medium (VTM). A lysis buffer mix from the MagMAX Pathogen RNA/DNA kit (Thermo Fisher), used on the KingFisher Flex, which included guanidinium isothiocyanate (GITC), a detergent, and isopropanol, demonstrated a minimum inactivation efficacy of 1 × 105 tissue culture infectious dose (TCID)50/ml. Alternative lysis buffer mixes from the MagMAX Viral/Pathogen Nucleic Acid kit (Thermo Fisher) also used on the KingFisher Flex and from the QIAamp 96 Virus QIAcube HT Kit (Qiagen) used on the QIAcube HT (both of which contained GITC and a detergent) reduced titres by 1 × 104 TCID50/ml but did not completely inactivate the virus. Heat treatment alone (15 min, 68°C) did not completely inactivate the virus, demonstrating a reduction of 1 × 103 TCID50/ml. When inactivation methods included both heat treatment and addition of lysis buffer, all methods were shown to completely inactivate SARS-CoV-2 inactivation against the viral titres tested. Results are discussed in the context of the operation of a high-throughput diagnostic laboratory.
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Affiliation(s)
- Ruth E Thom
- CBR Division, Dstl Porton Down, Salisbury, United Kingdom
| | - Lin S Eastaugh
- CBR Division, Dstl Porton Down, Salisbury, United Kingdom
| | - Lyn M O'Brien
- CBR Division, Dstl Porton Down, Salisbury, United Kingdom
| | - David O Ulaeto
- CBR Division, Dstl Porton Down, Salisbury, United Kingdom
| | | | | | | | | | | | - Simon A Weller
- CBR Division, Dstl Porton Down, Salisbury, United Kingdom
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4
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Hamblin KA, Flick-Smith H, Barnes KB, Pereira-Leal JB, Surkont J, Hampson R, Atkins HS, Harding SV. Disulfiram, an alcohol dependence therapy, can inhibit the in vitro growth of Francisella tularensis. Int J Antimicrob Agents 2019; 54:85-88. [DOI: 10.1016/j.ijantimicag.2019.04.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 04/04/2019] [Accepted: 04/06/2019] [Indexed: 10/27/2022]
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5
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Huang J, Nguyen VH, Hamblin KA, Maytum R, van der Giezen M, Fraser ME. ATP-specificity of succinyl-CoA synthetase from Blastocystis hominis. Acta Crystallogr D Struct Biol 2019; 75:647-659. [PMID: 31282474 DOI: 10.1107/s2059798319007976] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 06/03/2019] [Indexed: 11/10/2022]
Abstract
Succinyl-CoA synthetase (SCS) catalyzes the only step of the tricarboxylic acid cycle that leads to substrate-level phosphorylation. Some forms of SCS are specific for ADP/ATP or for GDP/GTP, while others can bind all of these nucleotides, generally with different affinities. The theory of `gatekeeper' residues has been proposed to explain the nucleotide-specificity. Gatekeeper residues lie outside the binding site and create specific electrostatic interactions with incoming nucleotides to determine whether the nucleotides can enter the binding site. To test this theory, the crystal structure of the nucleotide-binding domain in complex with Mg2+-ADP was determined, as well as the structures of four proteins with single mutations, K46βE, K114βD, V113βL and L227βF, and one with two mutations, K46βE/K114βD. The crystal structures show that the enzyme is specific for ADP/ATP because of interactions between the nucleotide and the binding site. Nucleotide-specificity is provided by hydrogen-bonding interactions between the adenine base and Gln20β, Gly111β and Val113β. The O atom of the side chain of Gln20β interacts with N6 of ADP, while the side-chain N atom interacts with the carbonyl O atom of Gly111β. It is the different conformations of the backbone at Gln20β, of the side chain of Gln20β and of the linker that make the enzyme ATP-specific. This linker connects the two subdomains of the ATP-grasp fold and interacts differently with adenine and guanine bases. The mutant proteins have similar conformations, although the L227βF mutant shows structural changes that disrupt the binding site for the magnesium ion. Although the K46βE/K114βD double mutant of Blastocystis hominis SCS binds GTP better than ATP according to kinetic assays, only the complex with Mg2+-ADP was obtained.
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Affiliation(s)
- Ji Huang
- Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Vinh H Nguyen
- Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Karleigh A Hamblin
- Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, England
| | - Robin Maytum
- School of Life Sciences, University of Bedfordshire, University Square, Luton LU1 3JU, England
| | | | - Marie E Fraser
- Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
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6
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Barnes KB, Hamblin KA, Richards MI, Laws TR, Vente A, Atkins HS, Harding SV. The Fluoroquinolone Finafloxacin Protects BALB/c Mice Against an Intranasal Infection With Francisella tularensis Strain SchuS4. Front Microbiol 2019; 10:904. [PMID: 31118924 PMCID: PMC6504792 DOI: 10.3389/fmicb.2019.00904] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 04/09/2019] [Indexed: 01/07/2023] Open
Abstract
The efficacy of the novel fluoroquinolone finafloxacin was evaluated as a potential therapeutic in vitro and in vivo, following an intranasal infection of Francisella tularensis strain SchuS4 in BALB/c mice. We demonstrated that short treatment courses of finafloxacin provide high levels of protection, with a single dose resulting in a significant increase in time to death when compared to ciprofloxacin. In addition, following investigation into the window of opportunity for treatment, we have shown that finafloxacin can provided protection when administered up to 96 h post-challenge. This is particularly encouraging since mice displayed severe signs of disease at this time point. In summary, finafloxacin may be a promising therapy for use in the event of exposure to F. tularensis, perhaps enabling the treatment regimen to be shortened or if therapy is delayed. The efficacy of finafloxacin against other biological threat agents also warrants investigation.
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Affiliation(s)
- Kay B Barnes
- Defence Science and Technology Laboratory, Salisbury, United Kingdom
| | | | - Mark I Richards
- Defence Science and Technology Laboratory, Salisbury, United Kingdom
| | - Thomas R Laws
- Defence Science and Technology Laboratory, Salisbury, United Kingdom
| | | | - Helen S Atkins
- Defence Science and Technology Laboratory, Salisbury, United Kingdom.,University of Exeter, Exeter, United Kingdom.,London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Sarah V Harding
- Defence Science and Technology Laboratory, Salisbury, United Kingdom
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7
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Tsaousis AD, Hamblin KA, Elliott CR, Young L, Rosell-Hidalgo A, Gourlay CW, Moore AL, van der Giezen M. The Human Gut Colonizer Blastocystis Respires Using Complex II and Alternative Oxidase to Buffer Transient Oxygen Fluctuations in the Gut. Front Cell Infect Microbiol 2018; 8:371. [PMID: 30406045 PMCID: PMC6204527 DOI: 10.3389/fcimb.2018.00371] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 10/03/2018] [Indexed: 12/12/2022] Open
Abstract
Blastocystis is the most common eukaryotic microbe in the human gut. It is linked to irritable bowel syndrome (IBS), but its role in disease has been contested considering its widespread nature. This organism is well-adapted to its anoxic niche and lacks typical eukaryotic features, such as a cytochrome-driven mitochondrial electron transport. Although generally considered a strict or obligate anaerobe, its genome encodes an alternative oxidase. Alternative oxidases are energetically wasteful enzymes as they are non-protonmotive and energy is liberated in heat, but they are considered to be involved in oxidative stress protective mechanisms. Our results demonstrate that the Blastocystis cells themselves respire oxygen via this alternative oxidase thereby casting doubt on its strict anaerobic nature. Inhibition experiments using alternative oxidase and Complex II specific inhibitors clearly demonstrate their role in cellular respiration. We postulate that the alternative oxidase in Blastocystis is used to buffer transient oxygen fluctuations in the gut and that it likely is a common colonizer of the human gut and not causally involved in IBS. Additionally the alternative oxidase could act as a protective mechanism in a dysbiotic gut and thereby explain the absence of Blastocystis in established IBS environments.
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Affiliation(s)
- Anastasios D. Tsaousis
- RAPID Group, Laboratory of Molecular & Evolutionary Parasitology, School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Karleigh A. Hamblin
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
- Biosciences, University of Exeter, Exeter, United Kingdom
| | - Catherine R. Elliott
- Department of Biochemistry and Biomedicine, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Luke Young
- Department of Biochemistry and Biomedicine, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Alicia Rosell-Hidalgo
- Department of Biochemistry and Biomedicine, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Campbell W. Gourlay
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Anthony L. Moore
- Department of Biochemistry and Biomedicine, School of Life Sciences, University of Sussex, Brighton, United Kingdom
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8
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Hamblin KA, Armstrong SJ, Barnes KB, Davies C, Laws T, Blanchard JD, Harding SV, Atkins HS. Inhaled Liposomal Ciprofloxacin Protects against a Lethal Infection in a Murine Model of Pneumonic Plague. Front Microbiol 2017; 8:91. [PMID: 28220110 PMCID: PMC5292416 DOI: 10.3389/fmicb.2017.00091] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 01/13/2017] [Indexed: 12/28/2022] Open
Abstract
Inhalation of Yersinia pestis can lead to pneumonic plague, which without treatment is inevitably fatal. Two novel formulations of liposome-encapsulated ciprofloxacin, ‘ciprofloxacin for inhalation’ (CFI, Lipoquin®) and ‘dual release ciprofloxacin for inhalation’ (DRCFI, Pulmaquin®) containing CFI and ciprofloxacin solution, are in development. These were evaluated as potential therapies for infection with Y. pestis. In a murine model of pneumonic plague, human-like doses of aerosolized CFI, aerosolized DRCFI or intraperitoneal (i.p.) ciprofloxacin were administered at 24 h (representing prophylaxis) or 42 h (representing treatment) post-challenge. All three therapies provided a high level of protection when administered 24 h post-challenge. A single dose of CFI, but not DRCFI, significantly improved survival compared to a single dose of ciprofloxacin. Furthermore, single doses of CFI and DRCFI reduced bacterial burden in lungs and spleens to below the detectable limit at 60 h post-challenge. When therapy was delayed until 42 h post-challenge, a single dose of CFI or DRCFI offered minimal protection. However, single doses of CFI or DRCFI were able to significantly reduce the bacterial burden in the spleen compared to empty liposomes. A three-day treatment regimen of ciprofloxacin, CFI, or DRCFI resulted in high levels of protection (90–100% survival). This study suggests that CFI and DRCFI may be useful therapies for Y. pestis infection, both as prophylaxis and for the treatment of plague.
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Affiliation(s)
- Karleigh A Hamblin
- CBR Division, Defence Science and Technology Laboratory, Porton Down Salisbury, UK
| | - Stuart J Armstrong
- CBR Division, Defence Science and Technology Laboratory, Porton Down Salisbury, UK
| | - Kay B Barnes
- CBR Division, Defence Science and Technology Laboratory, Porton Down Salisbury, UK
| | - Carwyn Davies
- CBR Division, Defence Science and Technology Laboratory, Porton Down Salisbury, UK
| | - Thomas Laws
- CBR Division, Defence Science and Technology Laboratory, Porton Down Salisbury, UK
| | | | | | - Helen S Atkins
- CBR Division, Defence Science and Technology Laboratory, Porton DownSalisbury, UK; Biosciences, University of ExeterExeter, UK
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9
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Vashisht K, Verma S, Gupta S, Lynn AM, Dixit R, Mishra N, Valecha N, Hamblin KA, Maytum R, Pandey KC, van der Giezen M. Engineering Nucleotide Specificity of Succinyl-CoA Synthetase in Blastocystis: The Emerging Role of Gatekeeper Residues. Biochemistry 2017; 56:534-542. [PMID: 27478903 PMCID: PMC5404824 DOI: 10.1021/acs.biochem.6b00098] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
![]()
Charged,
solvent-exposed residues at the entrance to the substrate
binding site (gatekeeper residues) produce electrostatic dipole interactions
with approaching substrates, and control their access by a novel mechanism
called “electrostatic gatekeeper effect”. This proof-of-concept
study demonstrates that the nucleotide specificity can be engineered
by altering the electrostatic properties of the gatekeeper residues
outside the binding site. Using Blastocystis succinyl-CoA
synthetase (SCS, EC 6.2.1.5), we demonstrated that the gatekeeper
mutant (ED) resulted in ATP-specific SCS to show high GTP specificity.
Moreover, nucleotide binding site mutant (LF) had no effect on GTP
specificity and remained ATP-specific. However, via combination of
the gatekeeper mutant with the nucleotide binding site mutant (ED+LF),
a complete reversal of nucleotide specificity was obtained with GTP,
but no detectable activity was obtained with ATP. This striking result
of the combined mutant (ED+LF) was due to two changes; negatively
charged gatekeeper residues (ED) favored GTP access, and nucleotide
binding site residues (LF) altered ATP binding, which was consistent
with the hypothesis of the “electrostatic gatekeeper effect”.
These results were further supported by molecular modeling and simulation
studies. Hence, it is imperative to extend the strategy of the gatekeeper
effect in a different range of crucial enzymes (synthetases, kinases,
and transferases) to engineer substrate specificity for various industrial
applications and substrate-based drug design.
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Affiliation(s)
- Kapil Vashisht
- Host-parasite Interaction Biology Group, National Institute of Malaria Research, ICMR , New Delhi 110077, India
| | - Sonia Verma
- Host-parasite Interaction Biology Group, National Institute of Malaria Research, ICMR , New Delhi 110077, India
| | - Sunita Gupta
- School of Computational and Integrative Sciences, Jawaharlal Nehru University , New Delhi 110067, India
| | - Andrew M Lynn
- School of Computational and Integrative Sciences, Jawaharlal Nehru University , New Delhi 110067, India
| | - Rajnikant Dixit
- Host-parasite Interaction Biology Group, National Institute of Malaria Research, ICMR , New Delhi 110077, India
| | - Neelima Mishra
- Host-parasite Interaction Biology Group, National Institute of Malaria Research, ICMR , New Delhi 110077, India
| | - Neena Valecha
- Host-parasite Interaction Biology Group, National Institute of Malaria Research, ICMR , New Delhi 110077, India
| | | | - Robin Maytum
- School of Life Sciences, University of Bedfordshire , University Square, Luton LU1 3JU, U.K
| | - Kailash C Pandey
- Host-parasite Interaction Biology Group, National Institute of Malaria Research, ICMR , New Delhi 110077, India
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10
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Hamblin KA, Wong JP, Blanchard JD, Atkins HS. The potential of liposome-encapsulated ciprofloxacin as a tularemia therapy. Front Cell Infect Microbiol 2014; 4:79. [PMID: 24995163 PMCID: PMC4062069 DOI: 10.3389/fcimb.2014.00079] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 05/26/2014] [Indexed: 11/13/2022] Open
Abstract
Liposome-encapsulation has been suggested as method to improve the efficacy of ciprofloxacin against the intracellular pathogen, Francisella tularensis. Early work with a prototype formulation, evaluated for use against the F. tularensis live vaccine strain, showed that a single dose of liposomal ciprofloxacin given by the intranasal or inhalational route could provide protection in a mouse model of pneumonic tularemia. Liposomal ciprofloxacin offered better protection than ciprofloxacin given by the same routes. Liposomal ciprofloxacin has been further developed by Aradigm Corporation for Pseudomonas aeruginosa infections in patients with cystic fibrosis and non-cystic fibrosis bronchiectasis. This advanced development formulation is safe, effective and well tolerated in human clinical trials. Further evaluation of the advanced liposomal ciprofloxacin formulation against the highly virulent F. tularensis Schu S4 strain has shown that aerosolized CFI (Ciprofloxacin encapsulated in liposomes for inhalation) provides significantly better protection than oral ciprofloxacin. Thus, liposomal ciprofloxacin is a promising treatment for tularemia and further research with the aim of enabling licensure under the animal rule is warranted.
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Affiliation(s)
- Karleigh A Hamblin
- Microbiology Group, Defence Science and Technology Laboratory, Biomedical Sciences Department , Porton Down, Salisbury, UK
| | - Jonathan P Wong
- Defence Research and Development Canada, Suffield Research Center , Ralston, AL, Canada
| | | | - Helen S Atkins
- Microbiology Group, Defence Science and Technology Laboratory, Biomedical Sciences Department , Porton Down, Salisbury, UK
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Flick-Smith HC, Fox MA, Hamblin KA, Richards MI, Jenner DC, Laws TR, Phelps AL, Taylor C, Harding SV, Ulaeto DO, Atkins HS. Assessment of antimicrobial peptide LL-37 as a post-exposure therapy to protect against respiratory tularemia in mice. Peptides 2013; 43:96-101. [PMID: 23500517 DOI: 10.1016/j.peptides.2013.02.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 02/28/2013] [Accepted: 02/28/2013] [Indexed: 11/20/2022]
Abstract
Early activation of the innate immune response is important for protection against infection with Francisella tularensis live vaccine strain (LVS) in mice. The human cathelicidin antimicrobial peptide LL-37 is known to have immunomodulatory properties, and therefore exogenously administered LL-37 may be suitable as an early post-exposure therapy to protect against LVS infection. LL-37 has been evaluated for immunostimulatory activity in uninfected mice and for activity against LVS in macrophage assays and protective efficacy when administered post-challenge in a mouse model of respiratory tularemia. Increased levels of pro-inflammatory cytokine IL-6, chemokines monocyte chemoattractant protein 1 (MCP-1) and CXCL1 with increased neutrophil influx into the lungs were observed in uninfected mice after intranasal administration of LL-37. Following LVS challenge, LL-37 administration resulted in increased IL-6, IL-12 p70, IFNγ and MCP-1 production, a slowing of LVS growth in the lung, and a significant extension of mean time to death compared to control mice. However, protection was transient, with the LL-37 treated mice eventually succumbing to infection. As this short course of nasally delivered LL-37 was moderately effective at overcoming the immunosuppressive effects of LVS infection this suggests that a more sustained treatment regimen may be an effective therapy against this pathogen.
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Affiliation(s)
- Helen C Flick-Smith
- Biomedical Sciences Department, Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire SP4 0JQ, United Kingdom.
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