29 results on '"Darren A. N. Cook"'
Search Results
2. Short-Course, High-Dose Rifampicin Achieves Wolbachia Depletion Predictive of Curative Outcomes in Preclinical Models of Lymphatic Filariasis and Onchocerciasis
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Ghaith Aljayyoussi, Hayley E. Tyrer, Louise Ford, Hanna Sjoberg, Nicolas Pionnier, David Waterhouse, Jill Davies, Joanne Gamble, Haelly Metuge, Darren A. N. Cook, Andrew Steven, Raman Sharma, Ana F. Guimaraes, Rachel H. Clare, Andrew Cassidy, Kelly L. Johnston, Laura Myhill, Laura Hayward, Samuel Wanji, Joseph D. Turner, Mark J. Taylor, and Stephen A. Ward
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Medicine ,Science - Abstract
Abstract Lymphatic filariasis (LF) and onchocerciasis are priority neglected tropical diseases targeted for elimination. The only safe drug treatment with substantial curative activity against the filarial nematodes responsible for LF (Brugia malayi, Wuchereria bancrofti) or onchocerciasis (Onchocerca volvulus) is doxycycline. The target of doxycycline is the essential endosymbiont, Wolbachia. Four to six weeks doxycycline therapy achieves >90% depletion of Wolbachia in worm tissues leading to blockade of embryogenesis, adult sterility and premature death 18–24 months post-treatment. Long treatment length and contraindications in children and pregnancy are obstacles to implementing doxycycline as a public health strategy. Here we determine, via preclinical infection models of Brugia malayi or Onchocerca ochengi that elevated exposures of orally-administered rifampicin can lead to Wolbachia depletions from filariae more rapidly than those achieved by doxycycline. Dose escalation of rifampicin achieves >90% Wolbachia depletion in time periods of 7 days in B. malayi and 14 days in O. ochengi. Using pharmacokinetic-pharmacodynamic modelling and mouse-human bridging analysis, we conclude that clinically relevant dose elevations of rifampicin, which have recently been determined as safe in humans, could be administered as short courses to filariasis target populations with potential to reduce anti-Wolbachia curative therapy times to between one and two weeks.
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- 2017
- Full Text
- View/download PDF
3. Author Correction: Short-Course, High-Dose Rifampicin Achieves Wolbachia Depletion Predictive of Curative Outcomes in Preclinical Models of Lymphatic Filariasis and Onchocerciasis
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Ghaith Aljayyoussi, Hayley E. Tyrer, Louise Ford, Hanna Sjoberg, Nicolas Pionnier, David Waterhouse, Jill Davies, Joanne Gamble, Haelly Metuge, Darren A. N. Cook, Andrew Steven, Raman Sharma, Ana F. Guimaraes, Rachel H. Clare, Andrew Cassidy, Kelly L. Johnston, Laura Myhill, Laura Hayward, Samuel Wanji, Joseph D. Turner, Mark J. Taylor, and Stephen A. Ward
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Medicine ,Science - Abstract
A correction to this article has been published and is linked from the HTML version of this paper. The error has been fixed in the paper.
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- 2018
- Full Text
- View/download PDF
4. Development of Pyrazolopyrimidine Anti-Wolbachia Agents for the Treatment of Filariasis
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Peter J. H. Webborn, Stefan Kavanagh, Andrew Cassidy, Paul M. O'Neill, Rachel H. Clare, Mark J. Taylor, Mark C. Wenlock, Neil G. Berry, W. David Hong, Darren A. N. Cook, Gemma L. Nixon, Stephen A. Ward, Paul McGillan, Suet C. Leung, Kelly L. Johnston, and Louise Ford
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wc_880 ,biology ,Phenotypic screening ,Organic Chemistry ,qv_38 ,Pharmacology ,biology.organism_classification ,medicine.disease ,Biochemistry ,Pyrazolopyrimidine ,In vitro ,Filariasis ,chemistry.chemical_compound ,chemistry ,In vivo ,Pharmacodynamics ,Drug Discovery ,medicine ,Wolbachia ,Lead compound - Abstract
Anti-Wolbachia therapy has been identified as a viable treatment for combating filarial diseases. Phenotypic screening revealed a series of pyrazolopyrimidine hits with potent anti-Wolbachia activity. This paper focuses on the exploration of the SAR for this chemotype, with improvement of metabolic stability and solubility profiles using medicinal chemistry approaches. Organic synthesis has enabled functionalization of the pyrazolopyrimidine core at multiple positions, generating a library of compounds of which many analogues possess nanomolar activity against Wolbachia in vitro with improved DMPK parameters. A lead compound, 15f, was selected for in vivo pharmacokinetics (PK) profiling in mice. The combination of potent anti-Wolbachia activity in two in vitro assessments plus the exceptional oral PK profiles in mice puts this lead compound in a strong position for in vivo proof-of-concept pharmacodynamics studies and demonstrates the strong potential for further optimization and development of this series for treatment of filariasis in the future.
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- 2021
5. X-treme loss of sequence diversity linked to neo-X chromosomes in filarial nematodes
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Shailja Misra-Bhattacharya, Andrew R. Moorhead, Lisa Sadzewicz, Darren A. N. Cook, Luke J. Tallon, Robin E. Bromley, Wanpen Chaicumpa, Jeremy M. Foster, Joseph D. Turner, Michelle L. Michalski, Andrew Steven, Benjamin C. Sparklin, Nikhil Kumar, Mohammad Behram Khan, Yee Ling Lau, Matthew Chung, Mark J. Taylor, Julie C. Dunning Hotopp, Silvia Libro, Atiporn Saeung, Ramakrishna U. Rao, John S. Mattick, and Mohd Shahab
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Nematoda ,RC955-962 ,Genome ,Brugia malayi ,qx_301 ,Arctic medicine. Tropical medicine ,Invertebrate Genomics ,Onchocerca ,Brugia Malayi ,X chromosome ,Genetics ,Sex Chromosomes ,biology ,Ecology ,Chromosome Biology ,Autosomes ,Eukaryota ,X Chromosomes ,Genomics ,wc_850 ,Infectious Diseases ,Public aspects of medicine ,RA1-1270 ,Research Article ,Brugia pahangi ,X Chromosome ,Ecological Metrics ,Chromosomes ,Helminths ,parasitic diseases ,Brugia ,Animals ,Chromosome Aberrations ,Genetic diversity ,Evolutionary Biology ,Genome, Helminth ,Autosome ,Population Biology ,Ecology and Environmental Sciences ,Public Health, Environmental and Occupational Health ,Organisms ,Chromosome ,Biology and Life Sciences ,Genetic Variation ,Species Diversity ,Cell Biology ,biology.organism_classification ,Invertebrates ,Animal Genomics ,Onchocerca Volvulus ,qu_470 ,Zoology ,human activities ,Population Genetics - Abstract
The sequence diversity of natural and laboratory populations of Brugia pahangi and Brugia malayi was assessed with Illumina resequencing followed by mapping in order to identify single nucleotide variants and insertions/deletions. In natural and laboratory Brugia populations, there is a lack of sequence diversity on chromosome X relative to the autosomes (πX/πA = 0.2), which is lower than the expected (πX/πA = 0.75). A reduction in diversity is also observed in other filarial nematodes with neo-X chromosome fusions in the genera Onchocerca and Wuchereria, but not those without neo-X chromosome fusions in the genera Loa and Dirofilaria. In the species with neo-X chromosome fusions, chromosome X is abnormally large, containing a third of the genetic material such that a sizable portion of the genome is lacking sequence diversity. Such profound differences in genetic diversity can be consequential, having been associated with drug resistance and adaptability, with the potential to affect filarial eradication., Author summary Almost a billion people receive >7.7 billion doses of treatment aimed at eliminating lymphatic filariasis, which is caused by three filarial nematodes: Wuchereria bancrofti, Brugia malayi, and Brugia timori. Drug resistance and adaptation are both associated with pathogen success as well as higher levels of genetic diversity. In an examination of genetic diversity in Brugia malayi and Brugia pahangi, we observed a lack of genetic diversity over a third of the genome that is found on chromosome X. These species have neo-X chromosomes where a chromosome X fused with an autosome. Using publicly-available published data, the other filarial nematodes of greatest human significance are also found to have a similar lack of genetic diversity on their neo-X chromosomes. The two filarial nematodes with publicly-available data that lack neo-X chromosomes did not have this lack of genetic diversity. This lack of sequence diversity in B. malayi, W. bancrofti, and O. volvulus could have profound effects on all traits encoded on chromosome X.
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- 2021
6. Preclinical development of an oral anti-Wolbachia macrolide drug for the treatment of lymphatic filariasis and onchocerciasis
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Sabine Specht, Thomas W. von Geldern, Kelly L. Johnston, Franziska Lenz, Samuel Wanji, Joseph D. Turner, Nicolas Pionnier, Abdel Jelil Njouendou, Dominique Bloemker, Darren A. N. Cook, Robert A. Carr, Louise Ford, Stephen A. Ward, Mark J. Taylor, Kennan C. Marsh, Marianne Koschel, Hanna T. Sjoberg, Howard E. Morton, Dale J. Kempf, John Archer, Hayley E. Tyrer, Haelly M. Metuge, Fanny Fri Fombad, Ghaith Aljayyoussi, Valerinne C. Chunda, Patrick W. N. Chounna, Rachel H. Clare, Marc P. Hübner, Alexandra Ehrens, Achim Hoerauf, Andrew Steven, and Emma A Murphy
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0301 basic medicine ,Doxycycline ,biology ,business.industry ,030231 tropical medicine ,General Medicine ,Minocycline ,Pharmacology ,biology.organism_classification ,medicine.disease ,Brugia malayi ,03 medical and health sciences ,Macrofilaricide ,chemistry.chemical_compound ,030104 developmental biology ,0302 clinical medicine ,chemistry ,parasitic diseases ,medicine ,Neglected tropical diseases ,Wolbachia ,Onchocerciasis ,business ,Lymphatic filariasis ,medicine.drug - Abstract
There is an urgent global need for a safe macrofilaricide drug to accelerate elimination of the neglected tropical diseases onchocerciasis and lymphatic filariasis. From an anti-infective compound library, the macrolide veterinary antibiotic, tylosin A, was identified as a hit against Wolbachia. This bacterial endosymbiont is required for filarial worm viability and fertility and is a validated target for macrofilaricidal drugs. Medicinal chemistry was undertaken to develop tylosin A analogs with improved oral bioavailability. Two analogs, A-1535469 and A-1574083, were selected. Their efficacy was tested against the gold-standard second-generation tetracycline antibiotics, doxycycline and minocycline, in mouse and gerbil infection models of lymphatic filariasis (Brugia malayi and Litomosoides sigmodontis) and onchocerciasis (Onchocerca ochengi). A 1- or 2-week course of oral A-1535469 or A-1574083 provided >90% Wolbachia depletion from nematodes in infected animals, resulting in a block in embryogenesis and depletion of microfilarial worm loads. The two analogs delivered comparative or superior efficacy compared to a 3- to 4-week course of doxycycline or minocycline. A-1574083 (now called ABBV-4083) was selected for further preclinical testing. Cardiovascular studies in dogs and toxicology studies in rats and dogs revealed no adverse effects at doses (50 mg/kg) that achieved plasma concentrations >10-fold above the efficacious concentration. A-1574083 (ABBV-4083) shows potential as an anti-Wolbachia macrolide with an efficacy, pharmacology, and safety profile that is compatible with a short-term oral drug course for treating lymphatic filariasis and onchocerciasis.
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- 2019
7. AWZ1066S, a highly specific anti-Wolbachia drug candidate for a short-course treatment of filariasis
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Paul M. O'Neill, Edward W. Tate, W. David Hong, Adam P. Roberts, Marc P. Hübner, Peter J. H. Webborn, Mark J. Taylor, Alexandra Ehrens, Stefan J. Frohberger, Dominique Struever, John Archer, Farid Benayoud, Joseph D. Turner, Rachel H. Clare, Achim Hoerauf, Stefan Kavanagh, Fabian Gusovsky, Andrew Steven, Neil G. Berry, Kelly L. Johnston, Ghaith Aljayyoussi, Andrew Cassidy, Remigiusz A. Serwa, Suet C. Leung, Janet Hemingway, Alasdair T. M. Hubbard, Gemma L. Nixon, Amy Siu, Stephen A. Ward, Emma A Murphy, Louise Ford, Li Qie, Motohiro Shiotani, and Darren A. N. Cook
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0301 basic medicine ,Drug ,MACROFILARICIDAL ACTIVITY ,Phenotypic screening ,media_common.quotation_subject ,030231 tropical medicine ,WUCHERERIA-BANCROFTI ,medicine.disease_cause ,Bioinformatics ,drug discovery ,Filariasis ,DOUBLE-BLIND ,03 medical and health sciences ,Macrofilaricide ,chemistry.chemical_compound ,0302 clinical medicine ,MD Multidisciplinary ,medicine ,BACTERIAL ENDOSYMBIONTS ,macrofilaricide ,lymphatic filariasis ,ELIMINATION ,Lymphatic filariasis ,media_common ,Science & Technology ,LITOMOSOIDES-SIGMODONTIS ,Multidisciplinary ,biology ,business.industry ,onchocerciasis ,ENDOBACTERIA ,anti-Wolbachia ,biology.organism_classification ,medicine.disease ,DOXYCYCLINE ,Multidisciplinary Sciences ,030104 developmental biology ,Wuchereria bancrofti ,chemistry ,Neglected tropical diseases ,Science & Technology - Other Topics ,Wolbachia ,ALBENDAZOLE ,business - Abstract
Onchocerciasis and lymphatic filariasis are two neglected tropical diseases that together affect ∼157 million people and inflict severe disability. Both diseases are caused by parasitic filarial nematodes with elimination efforts constrained by the lack of a safe drug that can kill the adult filaria (macrofilaricide). Previous proof-of-concept human trials have demonstrated that depleting >90% of the essential nematode endosymbiont bacterium, Wolbachia, using antibiotics, can lead to permanent sterilization of adult female parasites and a safe macrofilaricidal outcome. AWZ1066S is a highly specific anti-Wolbachia candidate selected through a lead optimization program focused on balancing efficacy, safety and drug metabolism/pharmacokinetic (DMPK) features of a thienopyrimidine/quinazoline scaffold derived from phenotypic screening. AWZ1066S shows superior efficacy to existing anti-Wolbachia therapies in validated preclinical models of infection and has DMPK characteristics that are compatible with a short therapeutic regimen of 7 days or less. This candidate molecule is well-positioned for onward development and has the potential to make a significant impact on communities affected by filariasis.
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- 2019
8. AWZ1066S, a highly specific anti
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W David, Hong, Farid, Benayoud, Gemma L, Nixon, Louise, Ford, Kelly L, Johnston, Rachel H, Clare, Andrew, Cassidy, Darren A N, Cook, Amy, Siu, Motohiro, Shiotani, Peter J H, Webborn, Stefan, Kavanagh, Ghaith, Aljayyoussi, Emma, Murphy, Andrew, Steven, John, Archer, Dominique, Struever, Stefan J, Frohberger, Alexandra, Ehrens, Marc P, Hübner, Achim, Hoerauf, Adam P, Roberts, Alasdair T M, Hubbard, Edward W, Tate, Remigiusz A, Serwa, Suet C, Leung, Li, Qie, Neil G, Berry, Fabian, Gusovsky, Janet, Hemingway, Joseph D, Turner, Mark J, Taylor, Stephen A, Ward, and Paul M, O'Neill
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Male ,Pharmacology ,onchocerciasis ,Mice, SCID ,Biological Sciences ,anti-Wolbachia ,Anti-Bacterial Agents ,drug discovery ,Mice ,Elephantiasis, Filarial ,Pyrimidines ,Quinazolines ,Animals ,Female ,macrofilaricide ,lymphatic filariasis ,Wolbachia - Abstract
Significance Onchocerciasis (river blindness) and lymphatic filariasis (elephantiasis) are neglected tropical diseases that cause severe disability and affect more than 157 million people globally. Current control efforts are hindered by the lack of a safe macrofilaricidal drug that can eliminate the parasitic adult nematodes safely. A clinically validated approach for delivering macrofilaricidal activity is to target the Wolbachia bacterial endosymbiont of the causative nematodes. This first-in-class and highly potent and specific anti-Wolbachia preclinical candidate molecule, AWZ1066S, has the potential to significantly impact current global onchocerciasis and lymphatic filariasis elimination programs and reduce elimination time frames from decades to years., Onchocerciasis and lymphatic filariasis are two neglected tropical diseases that together affect ∼157 million people and inflict severe disability. Both diseases are caused by parasitic filarial nematodes with elimination efforts constrained by the lack of a safe drug that can kill the adult filaria (macrofilaricide). Previous proof-of-concept human trials have demonstrated that depleting >90% of the essential nematode endosymbiont bacterium, Wolbachia, using antibiotics, can lead to permanent sterilization of adult female parasites and a safe macrofilaricidal outcome. AWZ1066S is a highly specific anti-Wolbachia candidate selected through a lead optimization program focused on balancing efficacy, safety and drug metabolism/pharmacokinetic (DMPK) features of a thienopyrimidine/quinazoline scaffold derived from phenotypic screening. AWZ1066S shows superior efficacy to existing anti-Wolbachia therapies in validated preclinical models of infection and has DMPK characteristics that are compatible with a short therapeutic regimen of 7 days or less. This candidate molecule is well-positioned for onward development and has the potential to make a significant impact on communities affected by filariasis.
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- 2019
9. Laboratory evaluation of molecular xenomonitoring using mosquito and tsetse fly excreta/feces to amplify Plasmodium, Brugia, and Trypanosoma DNA
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Nils Pilotte, Lisa J. Reimer, Corrado Minetti, Joseph Pryce, Michael F. Zulch, Steven A. Williams, and Darren A. N. Cook
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human African trypanosomiasis ,030231 tropical medicine ,malaria ,Medicine (miscellaneous) ,mosquito ,excreta/feces ,Trypanosoma brucei ,Biochemistry, Genetics and Molecular Biology (miscellaneous) ,Brugia malayi ,qy_25 ,qu_58.5 ,03 medical and health sciences ,molecular xenomonitoring ,0302 clinical medicine ,Immunology and Microbiology (miscellaneous) ,qx_301 ,wc_705 ,parasitic diseases ,Digital polymerase chain reaction ,030212 general & internal medicine ,lymphatic filariasis ,Pathogen ,biology ,Health Policy ,Public Health, Environmental and Occupational Health ,Tsetse fly ,Plasmodium falciparum ,Articles ,biology.organism_classification ,Virology ,qx_510 ,qx_135 ,Vector (epidemiology) ,surveillance ,Trypanosoma ,Research Article - Abstract
Background: Results from an increasing number of studies suggest that mosquito excreta/feces (E/F) testing has considerable potential to serve as a supplement for traditional molecular xenomonitoring techniques. However, as the catalogue of possible use-cases for this methodology expands, and the list of amenable pathogens grows, a number of fundamental methods-based questions remain. Answering these questions is critical to maximizing the utility of this approach and to facilitating its successful implementation as an effective tool for molecular xenomonitoring.Methods: Utilizing E/F produced by mosquitoes or tsetse flies experimentally exposed toBrugia malayi,Plasmodium falciparum, orTrypanosoma brucei brucei, factors such as limits of detection, throughput of testing, adaptability to use with competent and incompetent vector species, and effects of additional blood feedings post parasite-exposure were evaluated. Two platforms for the detection of pathogen signal (quantitative real-time PCR and digital PCR (dPCR)) were also compared, with strengths and weaknesses examined for each. Results: Experimental results indicated that high throughput testing is possible when evaluating mosquito E/F for the presence of eitherB. malayiorP. falciparumfrom both competent and incompetent vector mosquito species. Furthermore, following exposure to pathogen, providing mosquitoes with a second, uninfected bloodmeal did not expand the temporal window for E/F collection during which pathogen detection was possible. However, this collection window did appear longer in E/F collected from tsetse flies following exposure toT. b. brucei. Testing also suggested that dPCR may facilitate detection through its increased sensitivity. Unfortunately, logistical obstacles will likely make the large-scale use of dPCR impractical for this purpose.Conclusions: By examining many E/F testing variables, expansion of this technology to a field-ready platform has become increasingly feasible. However, translation of this methodology from the lab to the field will first require field-based pilot studies aimed at assessing the efficacy of E/F screening.
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- 2020
10. Laboratory evaluation of molecular xenomonitoring using mosquito excreta/feces to amplify Plasmodium, Brugia, and Trypanosoma DNA
- Author
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Michael F. Zulch, Darren A. N. Cook, Lisa J. Reimer, Steven A. Williams, Corrado Minetti, Joseph Pryce, and Nils Pilotte
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biology ,Health Policy ,030231 tropical medicine ,Public Health, Environmental and Occupational Health ,Medicine (miscellaneous) ,Plasmodium falciparum ,Computational biology ,Trypanosoma brucei ,biology.organism_classification ,medicine.disease ,Biochemistry, Genetics and Molecular Biology (miscellaneous) ,Brugia malayi ,03 medical and health sciences ,0302 clinical medicine ,Immunology and Microbiology (miscellaneous) ,Trypanosoma ,medicine ,Digital polymerase chain reaction ,030212 general & internal medicine ,Pathogen ,Feces ,Malaria - Abstract
Background: Results from an increasing number of studies suggest that mosquito excreta/feces (E/F) testing has considerable potential to serve as a supplement for traditional molecular xenomonitoring techniques. However, as the catalogue of possible use-cases for this methodology expands, and the list of amenable pathogens grows, a number of fundamental methods-based questions remain. Answering these questions is critical to maximizing the utility of this approach and to facilitating its successful implementation as an effective tool for molecular xenomonitoring.Methods: Utilizing E/F produced by mosquitoes or tsetse flies experimentally exposed toBrugia malayi,Plasmodium falciparum, orTrypanosoma brucei brucei, factors such as limits of detection, throughput of testing, adaptability to use with competent- and incompetent-vector species, and effects of additional blood feedings post parasite-exposure were evaluated. Two platforms for the detection of pathogen signal (quantitative real-time PCR and digital PCR [dPCR]) were also compared, with strengths and weaknesses examined for each. Results: Experimental results indicated that high throughput testing is possible when evaluating mosquito E/F for the presence of eitherB. malayiorP. falciparumfrom both competent- and incompetent-vector mosquito species. Furthermore, following exposure to pathogen, providing mosquitoes with a second, uninfected bloodmeal did not expand the temporal window for E/F collection during which pathogen detection was possible. However, this collection window did appear longer in E/F collected from tsetse flies following exposure toT. b. brucei. Testing also suggested that dPCR may facilitate detection through its increased sensitivity. Unfortunately, logistical obstacles will likely make the large-scale use of dPCR impractical for this purpose.Conclusions: By examining many E/F testing variables, expansion of this technology to a field-ready platform has become increasingly feasible. However, translation of this methodology from the lab to the field will first require the completion of field-based pilot studies aimed at assessing the efficacy of E/F screening.
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- 2019
11. Preclinical development of an oral anti
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Mark J, Taylor, Thomas W, von Geldern, Louise, Ford, Marc P, Hübner, Kennan, Marsh, Kelly L, Johnston, Hanna T, Sjoberg, Sabine, Specht, Nicolas, Pionnier, Hayley E, Tyrer, Rachel H, Clare, Darren A N, Cook, Emma, Murphy, Andrew, Steven, John, Archer, Dominique, Bloemker, Franziska, Lenz, Marianne, Koschel, Alexandra, Ehrens, Haelly M, Metuge, Valerinne C, Chunda, Patrick W, Ndongmo Chounna, Abdel J, Njouendou, Fanny F, Fombad, Robert, Carr, Howard E, Morton, Ghaith, Aljayyoussi, Achim, Hoerauf, Samuel, Wanji, Dale J, Kempf, Joseph D, Turner, and Stephen A, Ward
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Male ,Disease Models, Animal ,Mice, Inbred BALB C ,Elephantiasis, Filarial ,Treatment Outcome ,Administration, Oral ,Animals ,Female ,Tylosin ,Macrolides ,Mice, SCID ,Onchocerciasis ,Wolbachia - Abstract
There is an urgent global need for a safe macrofilaricide drug to accelerate elimination of the neglected tropical diseases onchocerciasis and lymphatic filariasis. From an anti-infective compound library, the macrolide veterinary antibiotic, tylosin A, was identified as a hit against
- Published
- 2018
12. Author Correction: Short-Course, High-Dose Rifampicin Achieves Wolbachia Depletion Predictive of Curative Outcomes in Preclinical Models of Lymphatic Filariasis and Onchocerciasis
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David Waterhouse, Laura Hayward, Samuel Wanji, Hayley E. Tyrer, Laura Myhill, Andrew Steven, Andrew Cassidy, Stephen A. Ward, Nicolas Pionnier, Hanna T. Sjoberg, Kelly L. Johnston, Joseph D. Turner, Mark J. Taylor, Rachel H. Clare, Jill Davies, Raman Sharma, Ghaith Aljayyoussi, Louise Ford, Ana F. Guimaraes, Haelly M. Metuge, Darren A. N. Cook, and Joanne Gamble
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DNA, Bacterial ,0301 basic medicine ,Science ,030231 tropical medicine ,Administration, Oral ,Embryonic Development ,Onchocerciasis ,Bioinformatics ,Article ,Mice ,03 medical and health sciences ,Elephantiasis, Filarial ,0302 clinical medicine ,parasitic diseases ,medicine ,Animals ,Humans ,Wuchereria bancrofti ,Short course ,Author Correction ,Brugia malayi ,Filarioidea ,Lymphatic filariasis ,Multidisciplinary ,biology ,business.industry ,qs_4 ,medicine.disease ,biology.organism_classification ,Anti-Bacterial Agents ,Disease Models, Animal ,Onchocerca volvulus ,Treatment Outcome ,030104 developmental biology ,Medicine ,Wolbachia ,Rifampin ,business ,Rifampicin ,medicine.drug - Abstract
Lymphatic filariasis (LF) and onchocerciasis are priority neglected tropical diseases targeted for elimination. The only safe drug treatment with substantial curative activity against the filarial nematodes responsible for LF (Brugia malayi, Wuchereria bancrofti) or onchocerciasis (Onchocerca volvulus) is doxycycline. The target of doxycycline is the essential endosymbiont, Wolbachia. Four to six weeks doxycycline therapy achieves >90% depletion of Wolbachia in worm tissues leading to blockade of embryogenesis, adult sterility and premature death 18–24 months post-treatment. Long treatment length and contraindications in children and pregnancy are obstacles to implementing doxycycline as a public health strategy. Here we determine, via preclinical infection models of Brugia malayi or Onchocerca ochengi that elevated exposures of orally-administered rifampicin can lead to Wolbachia depletions from filariae more rapidly than those achieved by doxycycline. Dose escalation of rifampicin achieves >90% Wolbachia depletion in time periods of 7 days in B. malayi and 14 days in O. ochengi. Using pharmacokinetic-pharmacodynamic modelling and mouse-human bridging analysis, we conclude that clinically relevant dose elevations of rifampicin, which have recently been determined as safe in humans, could be administered as short courses to filariasis target populations with potential to reduce anti-Wolbachia curative therapy times to between one and two weeks.
- Published
- 2018
13. Corrigendum: Minocycline as a re-purposed anti-Wolbachia macrofilaricide: superiority compared with doxycycline regimens in a murine infection model of human lymphatic filariasis
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Raman Sharma, Ghaith Aljayyoussi, Hayley E. Tyrer, Joanne Gamble, Laura Hayward, Ana F. Guimaraes, Jill Davies, David Waterhouse, Darren A. N. Cook, Laura J. Myhill, Rachel H. Clare, Andrew Cassidy, Andrew Steven, Kelly L. Johnston, Louise Ford, Joseph D. Turner, Stephen A. Ward, and Mark J. Taylor
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Male ,wc_880 ,Mice, Inbred BALB C ,Multidisciplinary ,Dose-Response Relationship, Drug ,qs_4 ,Minocycline ,Mice, SCID ,Corrigenda ,Anti-Bacterial Agents ,Disease Models, Animal ,Mice ,Elephantiasis, Filarial ,Doxycycline ,Animals ,Female ,Brugia malayi ,Wolbachia - Abstract
Lymphatic filariasis and onchocerciasis are parasitic helminth diseases, which cause severe morbidities such as elephantiasis, skin disease and blindness, presenting a major public health burden in endemic communities. The anti-Wolbachia consortium (A·WOL: http://www.a-wol.com/) has identified a number of registered antibiotics that target the endosymbiotic bacterium, Wolbachia, delivering macrofilaricidal activity. Here we use pharmacokinetics/pharmacodynamics (PK/PD) analysis to rationally develop an anti-Wolbachia chemotherapy by linking drug exposure to pharmacological effect. We compare the pharmacokinetics and anti-Wolbachia efficacy in a murine Brugia malayi model of minocycline versus doxycycline. Doxycycline exhibits superior PK in comparison to minocycline resulting in a 3-fold greater exposure in SCID mice. Monte-Carlo simulations confirmed that a bi-daily 25-40 mg/Kg regimen is bioequivalent to a clinically effective 100-200 mg/day dose for these tetracyclines. Pharmacodynamic studies showed that minocycline depletes Wolbachia more effectively than doxycycline (99.51% vs. 90.35%) after 28 day 25 mg/Kg bid regimens with a more potent block in microfilarial production. PK/PD analysis predicts that minocycline would be expected to be 1.7 fold more effective than doxycycline in man despite lower exposure in our infection models. Our findings warrant onward clinical investigations to examine the clinical efficacy of minocycline treatment regimens against lymphatic filariasis and onchocerciasis.
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- 2018
14. Albendazole and antibiotics synergize to deliver short-course anti- Wolbachia curative treatments in preclinical models of filariasis
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Mark J. Taylor, Rachel H. Clare, Louise Ford, Andrew Steven, Richard S. Priestley, Emma A Murphy, Joseph D. Turner, Janet Hemingway, Jill Davies, John McCall, David Waterhouse, Stephen A. Ward, Andrew Cassidy, Hayley E. Tyrer, Kelly L. Johnston, Raman Sharma, Darren A. N. Cook, Laura Hayward, Joanne Gamble, and Ghaith Al Jayoussi
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0301 basic medicine ,Combination therapy ,medicine.drug_class ,030231 tropical medicine ,Antibiotics ,Pharmacology ,Biology ,Albendazole ,Filariasis ,03 medical and health sciences ,Macrofilaricide ,chemistry.chemical_compound ,0302 clinical medicine ,parasitic diseases ,medicine ,Anthelmintic ,Multidisciplinary ,A100 ,biochemical phenomena, metabolism, and nutrition ,medicine.disease ,biology.organism_classification ,3. Good health ,030104 developmental biology ,Synergy ,chemistry ,Immunology ,bacteria ,Wolbachia ,medicine.drug - Abstract
Significance Filarial nematode infections, caused by Wuchereria bancrofti , Brugia malayi (elephantiasis), and Onchocerca volvulus (river blindness) infect 150 million of the world’s poorest populations and cause profound disability. Standard treatments require repetitive, long-term, mass drug administrations and have failed to interrupted transmission in certain sub-Saharan African regions. A drug cure using doxycycline, which targets the essential filarial endosymbiont Wolbachia , is clinically effective but programmatically challenging to implement due to long treatment durations and contraindications. Here we provide proof-of-concept of a radical improvement of targeting Wolbachia via identification of drug synergy between the anthelmintic albendazole and antibiotics. This synergy enables the shortening of treatment duration of macrofilaricidal anti- Wolbachia based treatments from 4 wk to 7 d with registered drugs ready for clinical testing.
- Published
- 2017
15. Development and Validation of a High-Throughput Anti-Wolbachia Whole-Cell Screen: A Route to Macrofilaricidal Drugs against Onchocerciasis and Lymphatic Filariasis
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Darren A. N. Cook, Louise Ford, Mark J. Taylor, Kelly L. Johnston, Stephen A. Ward, and Rachel H. Clare
- Subjects
Computational biology ,Biology ,Onchocerciasis ,Biochemistry ,Cell Line ,Analytical Chemistry ,Elephantiasis, Filarial ,Drug Discovery ,medicine ,Animals ,Humans ,Throughput (business) ,Lymphatic filariasis ,Dose-Response Relationship, Drug ,Drug discovery ,Antinematodal Agents ,Neglected Diseases ,Reproducibility of Results ,medicine.disease ,biology.organism_classification ,Anti-Bacterial Agents ,High-Throughput Screening Assays ,High-content screening ,Immunology ,Molecular Medicine ,Wolbachia ,Classical pharmacology ,Onchocerca ,Whole cell ,Biotechnology - Abstract
There is an urgent need to develop new, safe, and affordable macrofilaricidal drugs for onchocerciasis and lymphatic filariasis treatment and control. The Anti-Wolbachia Consortium (A·WOL) aims to provide a novel treatment with macrofilaricidal activity by targeting the essential bacterial symbiont Wolbachia. The consortium is currently screening a diverse range of compounds to find new chemical space to drive this drug discovery initiative and address this unmet demand. To increase the throughput and capacity of the A·WOL cell-based screen, we have developed a 384-well format assay using a high-content imaging system (Operetta) in conjunction with optimized Wolbachia growth dynamics in the C6/36 Aedes albopictus mosquito cell line. This assay uses texture analysis of cells stained with SYTO 11 as a direct measure of bacterial load. This validated assay has dramatically increased the capacity and throughput of the A·WOL compound library screening program 25-fold, enriching the number of new anti-Wolbachia hits identified for further development as potential macrofilaricides for onchocerciasis and lymphatic filariasis.
- Published
- 2015
16. Short-Course, High-Dose Rifampicin Achieves Wolbachia Depletion Predictive of Curative Outcomes in Preclinical Models of Lymphatic Filariasis and Onchocerciasis
- Author
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Jill Davies, Nicolas Pionnier, Hanna T. Sjoberg, Laura Hayward, Samuel Wanji, Ana F. Guimaraes, David Waterhouse, Hayley E. Tyrer, Joanne Gamble, Joseph D. Turner, Andrew Steven, Rachel H. Clare, Louise Ford, Laura Myhill, Mark J. Taylor, Stephen A. Ward, Ghaith Aljayyoussi, Darren A. N. Cook, Andrew Cassidy, Raman Sharma, Haelly M. Metuge, and Kelly L. Johnston
- Subjects
0301 basic medicine ,Science ,C111 ,030231 tropical medicine ,medicine.disease_cause ,Brugia malayi ,Filariasis ,03 medical and health sciences ,0302 clinical medicine ,parasitic diseases ,medicine ,Lymphatic filariasis ,Doxycycline ,Multidisciplinary ,biology ,biology.organism_classification ,medicine.disease ,Onchocerca volvulus ,3. Good health ,030104 developmental biology ,Wuchereria bancrofti ,Immunology ,Medicine ,Wolbachia ,Onchocerciasis ,medicine.drug - Abstract
Lymphatic filariasis (LF) and onchocerciasis are priority neglected tropical diseases targeted for elimination. The only safe drug treatment with substantial curative activity against the filarial nematodes responsible for LF (Brugia malayi, Wuchereria bancrofti) or onchocerciasis (Onchocerca volvulus) is doxycycline. The target of doxycycline is the essential endosymbiont, Wolbachia. Four to six weeks doxycycline therapy achieves >90% depletion of Wolbachia in worm tissues leading to blockade of embryogenesis, adult sterility and premature death 18–24 months post-treatment. Long treatment length and contraindications in children and pregnancy are obstacles to implementing doxycycline as a public health strategy. Here we determine, via preclinical infection models of Brugia malayi or Onchocerca ochengi that elevated exposures of orally-administered rifampicin can lead to Wolbachia depletions from filariae more rapidly than those achieved by doxycycline. Dose escalation of rifampicin achieves >90% Wolbachia depletion in time periods of 7 days in B. malayi and 14 days in O. ochengi. Using pharmacokinetic-pharmacodynamic modelling and mouse-human bridging analysis, we conclude that clinically relevant dose elevations of rifampicin, which have recently been determined as safe in humans, could be administered as short courses to filariasis target populations with potential to reduce anti-Wolbachia curative therapy times to between one and two weeks.
- Published
- 2017
17. Filarial infection influences mosquito behaviour and fecundity
- Author
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Mark J. Taylor, Lisa J. Reimer, Darren A. N. Cook, and Katherine Gleave
- Subjects
0301 basic medicine ,Mosquito Control ,030231 tropical medicine ,Aedes aegypti ,Article ,Brugia malayi ,Filariasis ,03 medical and health sciences ,Elephantiasis, Filarial ,0302 clinical medicine ,Aedes ,parasitic diseases ,medicine ,Animals ,Humans ,Lymphatic filariasis ,Multidisciplinary ,Behavior, Animal ,biology ,Host (biology) ,fungi ,biology.organism_classification ,Fecundity ,medicine.disease ,Virology ,Insect Vectors ,Mosquito control ,030104 developmental biology ,Larva ,Female - Abstract
Understanding vector-parasite interactions is increasingly important as we move towards the endpoint goals set by the Global Programme for the Elimination of Lymphatic Filariasis (GPELF), as interaction dynamics may change with reduced transmission pressure. Elimination models used to predict programmatic endpoints include parameters for vector-specific transmission dynamics, despite the fact that our knowledge of the host-seeking behaviour of filariasis infected mosquitoes is lacking. We observed a dynamic, stage-specific and density dependent change in Aedes aegypti behaviour towards host cues when exposed to Brugia malayi filarial parasites. Infected mosquitoes exhibited reduced activation and flight towards a host during the period of larval development (L1/L2), transitioning to a 5 fold increase in activation and flight towards a host when infective stage larvae (L3) were present (p
- Published
- 2016
18. Minocycline as a re-purposed anti-Wolbachia macrofilaricide: superiority compared with doxycycline regimens in a murine infection model of human lymphatic filariasis
- Author
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Joanne Gamble, David Waterhouse, Laura Myhill, Jill Davies, Rachel H. Clare, Hayley E. Tyrer, Andrew Cassidy, Stephen A. Ward, Laura Hayward, Darren A. N. Cook, Ana F. Guimaraes, Louise Ford, Ghaith Al Jayoussi, Andrew Steven, Raman Sharma, Kelly L. Johnston, Mark J. Taylor, and Joseph D. Turner
- Subjects
0301 basic medicine ,030231 tropical medicine ,C111 ,Pharmacology ,Article ,Brugia malayi ,Filariasis ,03 medical and health sciences ,Macrofilaricide ,chemistry.chemical_compound ,0302 clinical medicine ,parasitic diseases ,medicine ,Lymphatic filariasis ,Doxycycline ,Multidisciplinary ,biology ,business.industry ,Minocycline ,biology.organism_classification ,medicine.disease ,3. Good health ,Regimen ,030104 developmental biology ,chemistry ,Pharmacodynamics ,Immunology ,business ,medicine.drug - Abstract
Lymphatic filariasis and onchocerciasis are parasitic helminth diseases, which cause severe morbidities such as elephantiasis, skin disease and blindness, presenting a major public health burden in endemic communities. The anti-Wolbachia consortium (A·WOL: http://www.a-wol.com/) has identified a number of registered antibiotics that target the endosymbiotic bacterium, Wolbachia, delivering macrofilaricidal activity. Here we use pharmacokinetics/pharmacodynamics (PK/PD) analysis to rationally develop an anti-Wolbachia chemotherapy by linking drug exposure to pharmacological effect. We compare the pharmacokinetics and anti-Wolbachia efficacy in a murine Brugia malayi model of minocycline versus doxycycline. Doxycycline exhibits superior PK in comparison to minocycline resulting in a 3-fold greater exposure in SCID mice. Monte-Carlo simulations confirmed that a bi-daily 25–40 mg/Kg regimen is bioequivalent to a clinically effective 100–200 mg/day dose for these tetracyclines. Pharmacodynamic studies showed that minocycline depletes Wolbachia more effectively than doxycycline (99.51% vs. 90.35%) after 28 day 25 mg/Kg bid regimens with a more potent block in microfilarial production. PK/PD analysis predicts that minocycline would be expected to be 1.7 fold more effective than doxycycline in man despite lower exposure in our infection models. Our findings warrant onward clinical investigations to examine the clinical efficacy of minocycline treatment regimens against lymphatic filariasis and onchocerciasis.
- Published
- 2016
19. Research strategies to improve snakebite treatment: Challenges and progress
- Author
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Robert A. Harrison, Darren A. N. Cook, Nicholas R. Casewell, Rachel B. Currier, Simon C. Wagstaff, and Camila Renjifo
- Subjects
Organizations ,medicine.medical_specialty ,Antivenins ,business.industry ,International Cooperation ,Research ,Biophysics ,Snake Bites ,Biochemistry ,Disadvantaged ,Research strategies ,Research community ,Intervention (counseling) ,medicine ,Humans ,Effective treatment ,Preventable death ,Intensive care medicine ,business ,Delivery of Health Care - Abstract
Antivenom is an effective treatment of snakebite but, because of the complex interplay of fiscal, epidemiological, therapeutic efficacy and safety issues, the mortality of snakebite remains unacceptably high. Efficiently combating this high level of preventable death amongst the world's most disadvantaged communities requires the globally-coordinated action of multiple intervention programmes. This is the overall objective of the Global Snakebite Initiative. This paper describes the challenges facing the research community to develop snakebite treatments that are more efficacious, safe and affordable than current therapy.
- Published
- 2011
20. Analysis of camelid antibodies for antivenom development: Neutralisation of venom-induced pathology
- Author
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Simon C. Wagstaff, Ulrich Wernery, Timothy Owen, Robert A. Harrison, Joerg Kinne, and Darren A. N. Cook
- Subjects
Male ,endocrine system ,Echis ocellatus ,Camelus ,biology ,Antivenins ,Antivenom ,Enzyme-Linked Immunosorbent Assay ,Venom ,Toxicology ,biology.organism_classification ,complex mixtures ,Antibodies ,Bitis ,Echis ,Neutralization Tests ,Immunology ,Animals ,Female ,Snake antivenom ,Naja nigricollis ,Spitting cobra ,Snake Venoms - Abstract
Camelid IgG has been reported to be less immunogenic, less able to activate the complement cascade and more thermostable than IgG from other mammals, and has the ability to bind antigens that are unreactive with other mammalian IgGs. We are investigating whether these attributes of camelid IgG translate into antivenom with immunological and venom-neutralising efficacy advantages over conventional equine and ovine antivenoms. The objective of this study was to determine the preclinical venom-neutralising effectiveness of IgG from camels immunised with venoms, individually or in combination, of the saw-scaled viper, Echis ocellatus, the puff adder, Bitis arietans and the spitting cobra, Naja nigricollis - the most medically-important snake species in West Africa. Neutralisation of the pathological effects of venoms from E. ocellatus, B. arietans and N. nigricollis by IgG from the venom-immunised camels, or commercial antivenom, was compared using assays of venom lethality (ED(50)), haemorrhage (MHD) and coagulopathy (MCD). The E. ocellatus venom ED(50), MHD and MCD results of the E. ocellatus monospecific camel IgG antivenom were broadly equivalent to comparable ovine (EchiTAbG, MicroPharm Ltd, Wales) and equine (SAIMR Echis, South African Vaccine Producer, South Africa) antivenoms, although the equine antivenom required half the amount of IgG. The B. arietans monospecific camel IgG neutralised the lethal effects of B. arietans venom at one fourth the concentration of the SAIMR polyspecific antivenom (a monospecific B. arietans antivenom is not available). The N. nigricollis camel IgG antivenom was ineffective (at the maximum permitted dose, 100 mul) against the lethal effects of N. nigricollis venom. All the equine polyspecific antivenoms required more than 100 microl to be effective against this venom. The polyspecific camel IgG antivenom, prepared from five camels, was effective against the venom-induced effects of E. ocellatus but not against that of B. arietans and N. nigricollis venoms. No direct correlation was evident between either camel IgG relative avidity or titre and the effectiveness of venom neutralisation in preclinical assays.
- Published
- 2010
21. Analysis of camelid IgG for antivenom development: Immunoreactivity and preclinical neutralisation of venom-induced pathology by IgG subclasses, and the effect of heat treatment
- Author
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Robert A. Harrison, Ulrich Wernery, Chamali L. Samarasekara, Darren A. N. Cook, Simon C. Wagstaff, and Joerg Kinne
- Subjects
Camelus ,Hot Temperature ,Antivenom ,Snake Bites ,Hemorrhage ,Venom ,Viper Venoms ,Biology ,Toxicology ,complex mixtures ,Neutralization ,Subclass ,Mice ,Antibody Specificity ,Viperidae ,biology.animal ,Animals ,Avidity ,Snake antivenom ,Blood Coagulation ,Antivenins ,biology.organism_classification ,Immunoglobulin G ,Immunology ,Camelid - Abstract
Antivenom is the most effective treatment of snake envenoming and is manufactured from the IgG of venom-immunised horses and sheep. Camelids have a unique IgG structure which may account for the report that camel IgG is less immunogenic and less likely to activate complement than equine or ovine IgG. Camelid IgG therefore offers potential safety advantages over conventional IgGs used for antivenom manufacture. The reported thermostability of camelid IgG also holds promise in the inclusion of a relatively inexpensive anti-microbial heat step in antivenom manufacture. However, these potential benefits of camelid IgG would be much reduced if any one of the three camel IgG subclasses dominated, or under-performed, the serological response of camels to venom immunisation because of the prohibitive manufacturing costs of having to purify, or exclude, one or more IgG subclasses. This study compared the titre, antigen-specificity, relative avidity and ability to neutralise the haemorrhagic and coagulopathic effects of Echis ocellatus venom of each IgG subclass from the venom-immunised camels. The results demonstrated that no one IgG subclass consistently out-performed or under-performed the others in their immunoreactivity to venom proteins and ability to neutralise venom-induced pathologies. We concluded therefore that IgG taken from a pool of immunised camels could be processed into antivenom without requiring the implementation of expensive chromatographic separations to select, or indeed to exclude, a specific IgG subclass. The immunoreactivity of the heavy and light chain, IgG1 subclass, was markedly more vulnerable to extreme heat treatment than the heavy chain-only IgG2 and IgG3 subclasses.
- Published
- 2010
22. A murine macrofilaricide pre-clinical screening model for onchocerciasis and lymphatic filariasis
- Author
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Samuel Wanji, Hayley E. Tyrer, Haelly M. Metuge, Peter Enyong, Chounna N.dongmo Winston Patrick, Joseph D. Turner, Kengne Ouafo J.onas Arnaud, Mark J. Taylor, Tayong Dizzle Bita Kwenti, Andrew Steven, Darren A. N. Cook, George Forsbrook, Alice Halliday, and Ana F. Guimaraes
- Subjects
Male ,wc_880 ,Anti-filarial ,Menotropins ,Mycology & Parasitology ,Mice, SCID ,Elephantiasis ,Onchocerciasis ,wc_885 ,Brugia malayi ,Mice ,Macrofilaricide ,chemistry.chemical_compound ,Elephantiasis, Filarial ,1108 Medical Microbiology ,qv_771 ,parasitic diseases ,Brugia ,medicine ,Animals ,Onchocerca ,Lymphatic filariasis ,Mice, Inbred BALB C ,biology ,business.industry ,Research ,A100 ,medicine.disease ,biology.organism_classification ,Filaricides ,Infectious Diseases ,1117 Public Health And Health Services ,chemistry ,Drug development ,Immunology ,Female ,Parasitology ,Gerbillinae ,business ,Wolbachia - Abstract
Background: New drugs effective against adult filariae (macrofilaricides) would accelerate the elimination of lymphatic filariasis and onchocerciasis. Anti-Onchocerca drug development is hampered by the lack of a facile model. We postulated that SCID mice could be developed as a fmacrofilaricide screening model.\ud \ud Methods: The filaricides: albendazole (ABZ), diethylcarbamazine (DEC), flubendazole (FBZ), ivermectin (IVM) and the\ud anti-Wolbachia macrofilaricide, minocycline (MIN) were tested in Brugia malayi (Bm)-parasitized BALB/c SCID mice vs\ud vehicle control (VC). Responses were compared to BALB/c wild type (WT). Onchocerca ochengi male worms or\ud onchocercomata were surgically implanted into BALB/c SCID, CB.17 SCID, BALB/c WT mice or Meriones gerbils. Survival\ud was evaluated at 7–15 days. BALB/c SCID were tested to evaluate the responsiveness of pre-clinical macrofilaricides FBZ\ud and rifapentine (RIFAP) against male Onchocerca.\ud \ud Results: WT and SCID responded with >95% efficacy following ABZ or DEC treatments against Bm larvae (P < 0.0001).\ud IVM was partially filaricidal against Bm larvae in WT and SCID (WT; 39.8%, P = 0.0356 and SCID; 56.7%, P = 0.026). SCID\ud responded similarly to WT following IVM treatment of microfilaraemias (WT; 79%, P = 0.0194. SCID; 76%, P = 0.0473). FBZ\ud induced a total macrofilaricidal response against adult Bm in WT and SCID (WT; P = 0.0067, SCID; P = 0.0071). MIN\ud induced a >90% reduction in Bm Wolbachia burdens (P < 0.0001) and a blockade of microfilarial release (P = 0.0215) in\ud SCID. Male Onchocerca survival was significantly higher in SCID vs WT mice, but not gerbils, after +15 days (60% vs 22% vs\ud 39% P = 0.0475). Onchocercoma implants had engrafted into host tissues, with evidence of neovascularisation, after +7\ud days and yielded viable macro/microfilariae ex vivo. FBZ induced a macrofilaricidal effect in Onchocerca male implanted\ud SCID at +5 weeks (FBZ; 1.67% vs VC; 43.81%, P = 0.0089). Wolbachia loads within male Onchocerca were reduced by 99%\ud in implanted SCID receiving RIFAP for +2 weeks.\ud \ud Conclusions: We have developed a ‘pan-filarial’ small animal research model that is sufficiently robust, with adequate\ud capacity and throughput, to screen existing and future pre-clinical candidate macrofilaricides. Pilot data suggests a murine\ud onchocercoma xenograft model is achievable.
- Published
- 2014
23. Brugia malayi microfilariae adhere to human vascular endothelial cells in a C3-dependent manner
- Author
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Jan Hendrik Schroeder, Alister Craig, Charlotte Lawson, Rachel A. Lawrence, David McCarthy, Tadge Szestak, Mark J. Taylor, and Darren A. N. Cook
- Subjects
0301 basic medicine ,Nematoda ,Physiology ,Pathogenesis ,Pathology and Laboratory Medicine ,Biochemistry ,Epithelium ,Brugia malayi ,0302 clinical medicine ,Animal Cells ,Medicine and Health Sciences ,Brugia Malayi ,Lymphatic filariasis ,Melatonin ,Flow Rate ,biology ,lcsh:Public aspects of medicine ,Physics ,Classical Mechanics ,Complement C3 ,qs_532 ,Body Fluids ,Cell biology ,Chemistry ,Blood ,Infectious Diseases ,medicine.anatomical_structure ,qx_510 ,Host-Pathogen Interactions ,Physical Sciences ,293T cells ,Cell lines ,Anatomy ,Cellular Types ,medicine.symptom ,Biological cultures ,Research Article ,Chemical Elements ,medicine.drug ,wc_880 ,lcsh:Arctic medicine. Tropical medicine ,lcsh:RC955-962 ,030231 tropical medicine ,Fluid Mechanics ,Continuum Mechanics ,03 medical and health sciences ,parasitic diseases ,Brugia ,Cell Adhesion ,Human Umbilical Vein Endothelial Cells ,medicine ,Animals ,Humans ,Cell adhesion ,Lung ,HEK 293 cells ,Organisms ,Public Health, Environmental and Occupational Health ,Biology and Life Sciences ,Endothelial Cells ,lcsh:RA1-1270 ,Epithelial Cells ,Fluid Dynamics ,Cell Biology ,Hypoxia (medical) ,biology.organism_classification ,medicine.disease ,Invertebrates ,Hormones ,Oxygen ,Research and analysis methods ,Biological Tissue ,030104 developmental biology ,Nematode ,Immunology ,qu_350 - Abstract
Brugia malayi causes the human tropical disease, lymphatic filariasis. Microfilariae (Mf) of this nematode live in the bloodstream and are ingested by a feeding mosquito vector. Interestingly, in a remarkable co-evolutionary adaptation, Mf appearance in the peripheral blood follows a circadian periodicity and reaches a peak when the mosquito is most likely to feed. For the remaining hours, the majority of Mf sequester in the lung capillaries. This circadian phenomenon has been widely reported and is likely to maximise parasite fitness and optimise transmission potential. However, the mechanism of Mf sequestration in the lungs remains largely unresolved. In this study, we demonstrate that B. malayi Mf can, directly adhere to vascular endothelial cells under static conditions and under flow conditions, they can bind at high (but not low) flow rates. High flow rates are more likely to be experienced diurnally. Furthermore, a non-periodic nematode adheres less efficiently to endothelial cells. Strikingly C3, the central component of complement, plays a crucial role in the adherence interaction. These novel results show that microfilariae have the ability to bind to endothelial cells, which may explain their sequestration in the lungs, and this binding is increased in the presence of inflammatory mediators.
- Published
- 2017
24. Medically important differences in snake venom composition are dictated by distinct postgenomic mechanisms
- Author
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Wolfgang Wüster, Libia Sanz, Simon C. Wagstaff, Davinia Pla, Juan J. Calvete, Sarah I. King, Nicholas R. Casewell, Fiona M.S. Bolton, Robert A. Harrison, and Darren A. N. Cook
- Subjects
Proteome ,Transcription, Genetic ,Snake Bites ,Venom ,Bioinformatics ,complex mixtures ,Evolution, Molecular ,Species Specificity ,Viperidae ,biology.animal ,Crotalid Venoms ,medicine ,Gene family ,Animals ,Gene ,Regulation of gene expression ,Multidisciplinary ,biology ,Neglected Diseases ,Venom Protein ,Biological Sciences ,medicine.disease ,Snake bites ,Gene Expression Regulation ,Snake venom ,Evolutionary biology ,Protein Biosynthesis ,Protein Processing, Post-Translational - Abstract
6 páginas, 4 figuras. Este artículo contiene información suplementaria online en: www.pnas.org/lookup/suppl/doi:10.1073/pnas.1405484111/-/DCSupplemental, Variation in venom composition is a ubiquitous phenomenon in snakes and occurs both interspecifically and intraspecifically. Venom variation can have severe outcomes for snakebite victims by rendering the specific antibodies found in antivenoms ineffective against heterologous toxins found in different venoms. The rapid evolutionary expansion of different toxin-encoding gene families in different snake lineages is widely perceived as the main cause of venom variation. However, this view is simplistic and disregards the understudied influence that processes acting on gene transcription and translation may have on the production of the venom proteome. Here, we assess the venom composition of six related viperid snakes and compare interspecific changes in the number of toxin genes, their transcription in the venom gland, and their translation into proteins secreted in venom. Our results reveal that multiple levels of regulation are responsible for generating variation in venom composition between related snake species. We demonstrate that differential levels of toxin transcription, translation, and their posttranslational modification have a substantial impact upon the resulting venom protein mixture. Notably, these processes act to varying extents on different toxin paralogs found in different snakes and are therefore likely to be as important as ancestral gene duplication events for generating compositionally distinct venom proteomes. Our results suggest that these processes may also contribute to altering the toxicity of snake venoms, and we demonstrate how this variability can undermine the treatment of a neglected tropical disease, snakebite., This work was funded by NERC UK Research Studentship NER/S/A/2006/14086 and Postdoctoral Research Fellowship NE/J018678/1 (to N.R.C.), access to the NERC Molecular Genetics Facility at the University of Edinburgh from Grant MGF150 (to W.W.), a Leverhulme Trust Grant F/00174/I (to W.W. and R.A.H.), a National Centre for the Replacement, Refinement and Reduction of Animals in Research Studentship NC/K500288/1 (to R.A.H.), Ministerio de Ciencia é Innovación (currently Ministerio de Economía y Competitividad), Madrid Grant BFU2010-17373 and the Generalitat Valenciana Grant PROMETEO/2010/005 (to J.J.C.).
- Published
- 2014
25. Autophagy regulates Wolbachia populations across diverse symbiotic associations
- Author
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Denis Voronin, Mark J. Taylor, Darren A. N. Cook, and Andrew Steven
- Subjects
Nematoda ,Population ,Parasitism ,Cell Line ,Bacterial Proteins ,parasitic diseases ,Autophagy ,Animals ,Symbiosis ,education ,reproductive and urinary physiology ,Brugia malayi ,Mutualism (biology) ,Genetics ,education.field_of_study ,Multidisciplinary ,biology ,Obligate ,Ecology ,TOR Serine-Threonine Kinases ,biochemical phenomena, metabolism, and nutrition ,biology.organism_classification ,Commensalism ,Drosophila melanogaster ,Nematode ,PNAS Plus ,bacteria ,Wolbachia ,Subcellular Fractions - Abstract
Wolbachia are widespread and abundant intracellular symbionts of arthropods and filarial nematodes. Their symbiotic relationships encompass obligate mutualism, commensalism, parasitism, and pathogenicity. A consequence of these diverse associations is that Wolbachia encounter a wide range of host cells and intracellular immune defense mechanisms of invertebrates, which they must evade to maintain their populations and spread to new hosts. Here we show that autophagy, a conserved intracellular defense mechanism and regulator of cell homeostasis, is a major immune recognition and regulatory process that determines the size of Wolbachia populations. The regulation of Wolbachia populations by autophagy occurs across all distinct symbiotic relationships and can be manipulated either chemically or genetically to modulate the Wolbachia population load. The recognition and activation of host autophagy is particularly apparent in rapidly replicating strains of Wolbachia found in somatic tissues of Drosophila and filarial nematodes. In filarial nematodes, which host a mutualistic association with Wolbachia , the use of antibiotics such as doxycycline to eliminate Wolbachia has emerged as a promising approach to their treatment and control. Here we show that the activation of host nematode autophagy reduces bacterial loads to the same magnitude as antibiotic therapy; thus we identify a bactericidal mode of action targeting Wolbachia that can be exploited for the development of chemotherapeutic agents against onchocerciasis, lymphatic filariasis, and heartworm.
- Published
- 2012
26. Analysis of camelid IgG for antivenom development: Serological responses of venom-immunised camels to prepare either monospecific or polyspecific antivenoms for West Africa
- Author
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Robert A. Harrison, Simon C. Wagstaff, Darren A. N. Cook, Ulrich Wernery, Joerg Kinne, and Timothy Owen
- Subjects
Echis ocellatus ,Camelus ,biology ,Antivenins ,Antivenom ,Enzyme-Linked Immunosorbent Assay ,Toxicology ,medicine.disease ,biology.organism_classification ,complex mixtures ,Snake bites ,Bitis ,Africa, Western ,Immunoglobulin G ,Immunology ,medicine ,Animals ,Avidity ,Snake antivenom ,Envenomation ,Camelid ,Snake Venoms - Abstract
Snake envenoming is a significant cause of mortality and morbidity in sub-Saharan Africa. The only effective treatment, antivenom, has been in short supply since the 1990s. Whilst the humanitarian response by some antivenom producers has significantly improved the situation, strategies to ensure the long term stability of antivenom supply are still necessary. We are investigating whether the potential safety and logistic advantages of camel IgG antivenom can be exploited to improve antivenom provision in many countries where snakebite is endemic. This study assessed the IgG titre, specificity and avidity of camels immunised with either individual venom or a mixture of venoms from the three most medically important snakes of West Africa, the saw-scale viper (Echis ocellatus), the puff adder (Bitis arietans) and the spitting cobra (Naja nigricollis). Seven of the eight immunised camels generated IgG titres and avidities comparable to, or exceeding, that of commercial equine and ovine antivenoms that are highly effective in envenomed patients. In this, the first of a series of reports on the potential utility of camelid IgG antivenom, we describe an immunisation protocol that induced potent, sustained serological response of very high antibody avidity. These attributes suggest, from an immunological perspective, that camel IgG antivenoms should be as efficacious as current equine and ovine antivenoms.
- Published
- 2010
27. Reply to Professor Ratanabanangkoon’s letter entitled ‘D.A.N. Cook et al.’s account of the immunization of camels is at variance with the ‘low dose, low volume multi-site’ immunization protocol’
- Author
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Ulrich Wernery, Simon C. Wagstaff, Robert A. Harrison, Joerg Kinne, and Darren A. N. Cook
- Subjects
Low volume ,Protocol (science) ,Pediatrics ,medicine.medical_specialty ,Immunization ,business.industry ,Immunology ,Low dose ,medicine ,Multi site ,Variance (accounting) ,Toxicology ,business - Published
- 2010
28. Pre-Clinical Assays Predict Pan-African Echis Viper Efficacy for a Species-Specific Antivenom
- Author
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Darren A. N. Cook, Wolfgang Wüster, Nandul Durfa, Nicholas R. Casewell, Abdulsalami Nasidi, Robert A. Harrison, and Simon C. Wagstaff
- Subjects
Veterinary medicine ,lcsh:Arctic medicine. Tropical medicine ,VIPeR ,lcsh:RC955-962 ,Immunoblotting ,030231 tropical medicine ,Antivenom ,Drug Evaluation, Preclinical ,Snake Bites ,Zoology ,Enzyme-Linked Immunosorbent Assay ,Venom ,Viper Venoms ,complex mixtures ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Echis ,Neutralization Tests ,Viperidae ,biology.animal ,medicine ,Animals ,Humans ,Envenomation ,Africa South of the Sahara ,030304 developmental biology ,0303 health sciences ,biology ,Antivenins ,business.industry ,lcsh:Public aspects of medicine ,Public Health, Environmental and Occupational Health ,lcsh:RA1-1270 ,Venom Protein ,medicine.disease ,biology.organism_classification ,Antibodies, Neutralizing ,Survival Analysis ,Snake bites ,3. Good health ,Disease Models, Animal ,Infectious Diseases ,Infectious Diseases/Neglected Tropical Diseases ,Electrophoresis, Polyacrylamide Gel ,business ,Research Article - Abstract
Background Snakebite is a significant cause of death and disability in subsistent farming populations of sub-Saharan Africa. Antivenom is the most effective treatment of envenoming and is manufactured from IgG of venom-immunised horses/sheep but, because of complex fiscal reasons, there is a paucity of antivenom in sub-Saharan Africa. To address the plight of thousands of snakebite victims in savannah Nigeria, the EchiTAb Study Group organised the production, testing and delivery of antivenoms designed to treat envenoming by the most medically-important snakes in the region. The Echis saw-scaled vipers have a wide African distribution and medical importance. In an effort to maximise the clinical utility of scarce antivenom resources in Africa, we aimed to ascertain, at the pre-clinical level, to what extent the E. ocellatus-specific EchiTAbG antivenom, which was designed specifically for Nigeria, neutralised the lethal activity of venom from two other African species, E. pyramidum leakeyi and E. coloratus. Methodology/Principal Findings Despite apparently quite distinctive venom protein profiles, we observed extensive cross-species similarity in the immuno-reactivity profiles of Echis species-specific antisera. Using WHO standard pre-clinical in vivo tests, we determined that the monospecific EchiTAbG antivenom was as effective at neutralising the venom-induced lethal effects of E. pyramidum leakeyi and E. coloratus as it was against E. ocellatus venom. Under the restricted conditions of this assay, the antivenom was ineffective against the lethal effects of venom from the non-African Echis species, E. carinatus sochureki. Conclusions/Significance Using WHO-recommended pre-clinical tests we have demonstrated that the new anti-E. ocellatus monospecific antivenom EchiTAbG, developed in response to the considerable snakebite-induced mortality and morbidity in Nigeria, neutralised the lethal effects of venoms from Echis species representing each taxonomic group of this genus in Africa. This suggests that this monospecific antivenom has potential to treat envenoming by most, perhaps all, African Echis species., Author Summary Snakebite is principally a health concern of rural poor communities. The high snakebite risk of subsistence farming and paucity of effective antivenoms in sub-Saharan Africa means that many communities remain unacceptably vulnerable to snakebite mortality and morbidity. There is therefore a compelling need to maximise the utility of the snakebite therapies that are available. To address Nigeria's severe snakebite problem, the government funded a collaboration of ministry officials, antivenom manufacturers and academics (the EchiTAb Study Group) to produce, test and deliver antivenom. Accordingly, we prepared EchiTAbG, an antivenom specific for envenoming by the saw-scaled viper (E. ocellatus) which is responsible for 80% of snakebite deaths in Nigeria. Since E. ocellatus is widely distributed across the West African savannah, EchiTAbG offers considerable therapeutic promise in many countries in the region. Since other Echis species represent public health concerns elsewhere in Africa, the objective of this study was to examine the pre-clinical intra-generic venom-neutralising efficacy of EchiTAbG. Our results suggest that EchiTAbG (Nigeria registration: A6-0078) has pan-African efficacy against Echis envenoming indicating that costly investment in region-specific antivenoms therefore may not be required. This represents an important progression to minimise development costs and maximise the delivery of snakebite therapy for the continent.
- Published
- 2010
29. Interleukin-4 activated macrophages mediate immunity to filarial helminth infection by sustaining CCR3-dependent eosinophilia.
- Author
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Joseph D Turner, Nicolas Pionnier, Julio Furlong-Silva, Hanna Sjoberg, Stephen Cross, Alice Halliday, Ana F Guimaraes, Darren A N Cook, Andrew Steven, Nico Van Rooijen, Judith E Allen, Stephen J Jenkins, and Mark J Taylor
- Subjects
Immunologic diseases. Allergy ,RC581-607 ,Biology (General) ,QH301-705.5 - Abstract
Eosinophils are effectors in immunity to tissue helminths but also induce allergic immunopathology. Mechanisms of eosinophilia in non-mucosal tissues during infection remain unresolved. Here we identify a pivotal function of tissue macrophages (Mϕ) in eosinophil anti-helminth immunity using a BALB/c mouse intra-peritoneal Brugia malayi filarial infection model. Eosinophilia, via C-C motif chemokine receptor (CCR)3, was necessary for immunity as CCR3 and eosinophil impairments rendered mice susceptible to chronic filarial infection. Post-infection, peritoneal Mϕ populations proliferated and became alternatively-activated (AAMϕ). Filarial AAMϕ development required adaptive immunity and interleukin-4 receptor-alpha. Depletion of Mϕ prior to infection suppressed eosinophilia and facilitated worm survival. Add back of filarial AAMϕ in Mϕ-depleted mice recapitulated a vigorous eosinophilia. Transfer of filarial AAMϕ into Severe-Combined Immune Deficient mice mediated immunological resistance in an eosinophil-dependent manner. Exogenous IL-4 delivery recapitulated tissue AAMϕ expansions, sustained eosinophilia and mediated immunological resistance in Mϕ-intact SCID mice. Co-culturing Brugia with filarial AAMϕ and/or filarial-recruited eosinophils confirmed eosinophils as the larvicidal cell type. Our data demonstrates that IL-4/IL-4Rα activated AAMϕ orchestrate eosinophil immunity to filarial tissue helminth infection.
- Published
- 2018
- Full Text
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