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Rasetti-Escargueil C, Popoff MR. Recent Developments in Botulinum Neurotoxins Detection. Microorganisms 2022; 10:microorganisms10051001. [PMID: 35630444 PMCID: PMC9145529 DOI: 10.3390/microorganisms10051001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 04/29/2022] [Accepted: 05/03/2022] [Indexed: 02/04/2023] Open
Abstract
Botulinum neurotoxins (BoNTs) are produced as protein complexes by bacteria of the genus Clostridium that are Gram-positive, anaerobic and spore forming (Clostridium botulinum, C. butyricum, C. baratii and C. argentinense spp.). BoNTs show a high immunological and genetic diversity. Therefore, fast, precise, and more reliable detection methods are still required to monitor outbreaks and ensure surveillance of botulism. The botulinum toxin field also comprises therapeutic uses, basic research studies and biodefense issues. This review presents currently available detection methods, and new methods offering the potential of enhanced precision and reproducibility. While the immunological methods offer a range of benefits, such as rapid analysis time, reproducibility and high sensitivity, their implementation is subject to the availability of suitable tools and reagents, such as specific antibodies. Currently, the mass spectrometry approach is the most sensitive in vitro method for a rapid detection of active or inactive forms of BoNTs. However, these methods require inter-laboratory validation before they can be more widely implemented in reference laboratories. In addition, these surrogate in vitro models also require full validation before they can be used as replacement bioassays of potency. Cell-based assays using neuronal cells in culture recapitulate all functional steps of toxin activity, but are still at various stages of development; they are not yet sufficiently robust, due to high batch-to-batch cell variability. Cell-based assays have a strong potential to replace the mouse bioassay (MBA) in terms of BoNT potency determination in pharmaceutical formulations; they can also help to identify suitable inhibitors while reducing the number of animals used. However, the development of safe countermeasures still requires the use of in vivo studies to complement in vitro immunological or cell-based approaches.
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Toxemia in Human Naturally Acquired Botulism. Toxins (Basel) 2020; 12:toxins12110716. [PMID: 33202855 PMCID: PMC7697460 DOI: 10.3390/toxins12110716] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/07/2020] [Accepted: 11/10/2020] [Indexed: 12/18/2022] Open
Abstract
Human botulism is a severe disease characterized by flaccid paralysis and inhibition of certain gland secretions, notably salivary secretions, caused by inhibition of neurotransmitter release. Naturally acquired botulism occurs in three main forms: food-borne botulism by ingestion of preformed botulinum neurotoxin (BoNT) in food, botulism by intestinal colonization (infant botulism and intestinal toxemia botulism in infants above one year and adults), and wound botulism. A rapid laboratory confirmation of botulism is required for the appropriate management of patients. Detection of BoNT in the patient's sera is the most direct way to address the diagnosis of botulism. Based on previous published reports, botulinum toxemia was identified in about 70% of food-borne and wound botulism cases, and only in about 28% of infant botulism cases, in which the diagnosis is mainly confirmed from stool sample investigation. The presence of BoNT in serum depends on the BoNT amount ingested with contaminated food or produced locally in the intestine or wound, and the timeframe between serum sampling and disease onset. BoNT levels in patient's sera are most frequently low, requiring a highly sensitive method of detection. Mouse bioassay is still the most used method of botulism identification from serum samples. However, in vitro methods based on BoNT endopeptidase activity with detection by mass spectrometry or immunoassay have been developed and depending on BoNT type, are more sensitive than the mouse bioassay. These new assays show high specificity for individual BoNT types and allow more accurate differentiation between positive toxin sera from botulism and autoimmune neuropathy patients.
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Hobbs RJ, Thomas CA, Halliwell J, Gwenin CD. Rapid Detection of Botulinum Neurotoxins-A Review. Toxins (Basel) 2019; 11:E418. [PMID: 31319550 PMCID: PMC6669533 DOI: 10.3390/toxins11070418] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 07/15/2019] [Accepted: 07/15/2019] [Indexed: 12/13/2022] Open
Abstract
A toxin is a poisonous substance produced within living cells or organisms. One of the most potent groups of toxins currently known are the Botulinum Neurotoxins (BoNTs). These are so deadly that as little as 62 ng could kill an average human; to put this into context that is approximately 200,000 × less than the weight of a grain of sand. The extreme toxicity of BoNTs leads to the need for methods of determining their concentration at very low levels of sensitivity. Currently the mouse bioassay is the most widely used detection method monitoring the activity of the toxin; however, this assay is not only lengthy, it also has both cost and ethical issues due to the use of live animals. This review focuses on detection methods both existing and emerging that remove the need for the use of animals and will look at three areas; speed of detection, sensitivity of detection and finally cost. The assays will have wide reaching interest, ranging from the pharmaceutical/clinical industry for production quality management or as a point of care sensor in suspected cases of botulism, the food industry as a quality control measure, to the military, detecting BoNT that has been potentially used as a bio warfare agent.
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Affiliation(s)
- Robert J Hobbs
- Applied Research in Chemistry and Health (ARCH) Research Group, School of Natural Sciences, Bangor University, Bangor, Gwynedd, Wales LL57 2UW, UK
| | - Carol A Thomas
- Applied Research in Chemistry and Health (ARCH) Research Group, School of Natural Sciences, Bangor University, Bangor, Gwynedd, Wales LL57 2UW, UK
| | - Jennifer Halliwell
- Applied Research in Chemistry and Health (ARCH) Research Group, School of Natural Sciences, Bangor University, Bangor, Gwynedd, Wales LL57 2UW, UK
| | - Christopher D Gwenin
- Applied Research in Chemistry and Health (ARCH) Research Group, School of Natural Sciences, Bangor University, Bangor, Gwynedd, Wales LL57 2UW, UK.
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von Berg L, Stern D, Pauly D, Mahrhold S, Weisemann J, Jentsch L, Hansbauer EM, Müller C, Avondet MA, Rummel A, Dorner MB, Dorner BG. Functional detection of botulinum neurotoxin serotypes A to F by monoclonal neoepitope-specific antibodies and suspension array technology. Sci Rep 2019; 9:5531. [PMID: 30940836 PMCID: PMC6445094 DOI: 10.1038/s41598-019-41722-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 03/15/2019] [Indexed: 12/26/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are the most potent toxins known and cause the life threatening disease botulism. Sensitive and broad detection is extremely challenging due to the toxins' high potency and molecular heterogeneity with several serotypes and more than 40 subtypes. The toxicity of BoNT is mediated by enzymatic cleavage of different synaptic proteins involved in neurotransmitter release at serotype-specific cleavage sites. Hence, active BoNTs can be monitored and distinguished in vitro by detecting their substrate cleavage products. In this work, we developed a comprehensive panel of monoclonal neoepitope antibodies (Neo-mAbs) highly specific for the newly generated N- and/or C-termini of the substrate cleavage products of BoNT serotypes A to F. The Neo-mAbs were implemented in a set of three enzymatic assays for the simultaneous detection of two BoNT serotypes each by monitoring substrate cleavage on colour-coded magnetic Luminex-beads. For the first time, all relevant serotypes could be detected in parallel by a routine in vitro activity assay in spiked serum and food samples yielding excellent detection limits in the range of the mouse bioassay or better (0.3-80 pg/mL). Therefore, this work represents a major step towards the replacement of the mouse bioassay for botulism diagnostics.
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Affiliation(s)
- Laura von Berg
- Biological Toxins (ZBS 3), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Berlin, 13353, Germany
| | - Daniel Stern
- Biological Toxins (ZBS 3), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Berlin, 13353, Germany
| | - Diana Pauly
- Biological Toxins (ZBS 3), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Berlin, 13353, Germany
- Department of Ophthalmology, University Hospital Regensburg, Regensburg, 93053, Germany
| | - Stefan Mahrhold
- Institut für Toxikologie, Medizinische Hochschule Hannover, 30625, Hannover, Germany
| | - Jasmin Weisemann
- Institut für Toxikologie, Medizinische Hochschule Hannover, 30625, Hannover, Germany
| | - Lisa Jentsch
- Biological Toxins (ZBS 3), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Berlin, 13353, Germany
| | - Eva-Maria Hansbauer
- Biological Toxins (ZBS 3), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Berlin, 13353, Germany
| | - Christian Müller
- Spiez Laboratory, Federal Office for Civil Protection, Spiez, 3700, Switzerland
| | - Marc A Avondet
- Spiez Laboratory, Federal Office for Civil Protection, Spiez, 3700, Switzerland
| | - Andreas Rummel
- Institut für Toxikologie, Medizinische Hochschule Hannover, 30625, Hannover, Germany
| | - Martin B Dorner
- Biological Toxins (ZBS 3), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Berlin, 13353, Germany
| | - Brigitte G Dorner
- Biological Toxins (ZBS 3), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Berlin, 13353, Germany.
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Yadirgi G, Stickings P, Rajagopal S, Liu Y, Sesardic D. Immuno-detection of cleaved SNAP-25 from differentiated mouse embryonic stem cells provides a sensitive assay for determination of botulinum A toxin and antitoxin potency. J Immunol Methods 2017; 451:90-99. [PMID: 28943257 DOI: 10.1016/j.jim.2017.09.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 09/19/2017] [Accepted: 09/20/2017] [Indexed: 01/12/2023]
Abstract
Botulinum toxin type A is a causative agent of human botulism. Due to high toxicity and ease of production it is classified by the Centres for Disease Control and Prevention as a category A bioterrorism agent. The same serotype, BoNT/A, is also the most widely used in pharmaceutical preparations for treatment of a diverse range of neuromuscular disorders. Traditionally, animals are used to confirm the presence and activity of toxin and to establish neutralizing capabilities of countermeasures in toxin neutralization tests. Cell based assays for BoNT/A have been reported as the most viable alternative to animal models, since they are capable of reflecting all key steps (binding, translocation, internalization and cleavage of intracellular substrate) involved in toxin activity. In this paper we report preliminary development of a simple immunochemical method for specifically detecting BoNT/A cleaved intracellular substrate, SNAP-25, in cell lysates of neurons derived from mouse embryonic stem cells. The assay offers sensitivity of better than 0.1LD50/ml (3fM) which is not matched by other functional assays, including the mouse bioassay, and provides serotype specificity for quantitative detection of BoNT/A and anti-BoNT/A antitoxin. Subject to formal validation, the method described here could potentially be used as a substitute for the mouse bioassay to measure potency and consistency of therapeutic products.
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Affiliation(s)
- G Yadirgi
- Division of Bacteriology, National Institute for Biological Standards and Control, a center of the Medicines and Healthcare Products Regulatory Agency, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK.
| | - P Stickings
- Division of Bacteriology, National Institute for Biological Standards and Control, a center of the Medicines and Healthcare Products Regulatory Agency, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK.
| | - S Rajagopal
- Division of Bacteriology, National Institute for Biological Standards and Control, a center of the Medicines and Healthcare Products Regulatory Agency, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK.
| | - Y Liu
- Division of Bacteriology, National Institute for Biological Standards and Control, a center of the Medicines and Healthcare Products Regulatory Agency, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK.
| | - D Sesardic
- Division of Bacteriology, National Institute for Biological Standards and Control, a center of the Medicines and Healthcare Products Regulatory Agency, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK.
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SiMa Cells for a Serotype Specific and Sensitive Cell-Based Neutralization Test for Botulinum Toxin A and E. Toxins (Basel) 2017; 9:toxins9070230. [PMID: 28726719 PMCID: PMC5535177 DOI: 10.3390/toxins9070230] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/18/2017] [Indexed: 12/15/2022] Open
Abstract
Botulinum toxins (BoNTs), of which there are seven serotypes, are among the most potent neurotoxins, with serotypes A, B and E causing human botulism. Antitoxins form the first line of treatment for botulism, and functional, highly sensitive in vitro methods for toxin neutralization are needed to replace the current in vivo methods used for determination of antitoxin potency. In this preliminary proof of concept study, we report the development of a neutralization test using the neuroblastoma SiMa cell line. The assay is serotype specific for either BoNT/A or BoNT/E, which both cleave unique sequences on SNAP-25 within SiMa cells. The end point is simple immunodetection of cleaved SNAP-25 from cell lysates with antibodies detecting only the newly exposed sequence on SNAP-25. Neutralizing antibodies prevent the toxin-induced cleavage of SNAP-25. The toxin neutralization assay, with an EC50 of ~2 mIU/mL determined with a standardized reference antiserum, is more sensitive than the mouse bioassays. Relevance was demonstrated with commercial and experimental antitoxins targeting different functional domains, and of known in vivo neutralizing activities. This is the first report describing a simple, specific, in vitro cell-based assay for the detection of neutralizing antibodies against BoNT/A and BoNT/E with a sensitivity exceeding that of the mouse bioassay.
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Pellett S, Tepp WH, Johnson EA, Sesardic D. Assessment of ELISA as endpoint in neuronal cell-based assay for BoNT detection using hiPSC derived neurons. J Pharmacol Toxicol Methods 2017; 88:1-6. [PMID: 28465161 DOI: 10.1016/j.vascn.2017.04.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 04/25/2017] [Accepted: 04/28/2017] [Indexed: 01/12/2023]
Abstract
INTRODUCTION Botulinum neurotoxins (BoNTs), the causative agents of botulism, are widely used as powerful bio-pharmaceuticals to treat neuro-muscular disorders. Due to the high potency and potential lethality of BoNTs, careful monitoring of the biologic activity of BoNT-based pharmaceuticals is required to ensure safe usage. For decades, the only approved method for potency determination of pharmaceutical BoNTs was the mouse bioassay (MBA), but in recent years improvements in cell-assay technologies have enabled MBA replacement by cell-based assays for specific product evaluations. This project details a method for quantitative and sensitive detection of biologic activity of BoNT/A1 in human induced pluripotent stem cell (hiPSC) derived neurons using an ELISA as a method to determine SNAP-25 cleavage by BoNT/A1 following toxin exposure. METHODS HiPSC derived neurons from two different sources were exposed to serial dilutions of BoNT/A1, and quantitative detection of toxin activity was evaluated and optimized in cell lysates using ELISA to detect cleaved SNAP-25. RESULTS The results from this study indicate that an ELISA using ultra TMB as a substrate quantitatively detects cleaved SNAP-25 in cell lysates of BoNT/A1 exposed hiPSC-derived neuronal cells with similar or greater sensitivity as Western blot (EC50~0.3U/well). DISCUSSION This study demonstrates a human specific and sensitive cell-based detection platform of BoNT/A1 activity using ELISA as an endpoint for quantitative detection of the SNAP-25 cleavage product. This assay is applicable to moderate to high-throughput formats and importantly employs non-cancerous human-specific neuronal cells for potency evaluation of a bio-pharmaceutical for human use.
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Affiliation(s)
- Sabine Pellett
- Department of Bacteriology, University of Wisconsin, 1550 Linden Dr., Madison, WI 53706, United States.
| | - William H Tepp
- Department of Bacteriology, University of Wisconsin, 1550 Linden Dr., Madison, WI 53706, United States.
| | - Eric A Johnson
- Department of Bacteriology, University of Wisconsin, 1550 Linden Dr., Madison, WI 53706, United States.
| | - Dorothea Sesardic
- Division of Bacteriology, National Institute for Biological Standards and Control (NIBSC), A centre of Medicines and Healthcare products Regulatory Agency; Hertfordshire EN6 3QG, UK.
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Desplantes R, Lévêque C, Muller B, Lotierzo M, Ferracci G, Popoff M, Seagar M, Mamoun R, El Far O. Affinity biosensors using recombinant native membrane proteins displayed on exosomes: application to botulinum neurotoxin B receptor. Sci Rep 2017; 7:1032. [PMID: 28432329 PMCID: PMC5430821 DOI: 10.1038/s41598-017-01198-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 03/27/2017] [Indexed: 12/31/2022] Open
Abstract
The development of simple molecular assays with membrane protein receptors in a native conformation still represents a challenging task. Exosomes are extracellular vesicles which, due to their stability and small size, are suited for analysis in various assay formats. Here, we describe a novel approach to sort recombinant fully native and functional membrane proteins to exosomes using a targeting peptide. Specific binding of high affinity ligands to the potassium channel Kv1.2, the G-protein coupled receptor CXCR4, and the botulinum neurotoxin type B (BoNT/B) receptor, indicated their correct assembly and outside out orientation in exosomes. We then developed, using a label-free optical biosensor, a new method to determine the kinetic constants of BoNT/B holotoxin binding to its receptor synaptotagmin2/GT1b ganglioside (kon = 2.3 ×105 M−1.s−1, koff = 1.3 10−4 s−1), yielding an affinity constant (KD = 0.6 nM) similar to values determined from native tissue. In addition, the recombinant binding domain of BoNT/B, a potential vector for neuronal delivery, bound quasi-irreversibly to synaptotagmin 2/GT1b exosomes. Engineered exosomes provide thus a novel means to study membrane proteins for biotechnology and clinical applications.
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Affiliation(s)
- Richard Desplantes
- INSERM, UMR_S 1072, 13015, Marseille, France.,Aix-Marseille Université, 13015, Marseille, France
| | - Christian Lévêque
- INSERM, UMR_S 1072, 13015, Marseille, France.,Aix-Marseille Université, 13015, Marseille, France
| | - Benjamin Muller
- Ciloa, cc90 - Université Montpellier 2, Place E. Bataillon, 34095, Montpellier Cedex 5, France
| | - Manuela Lotierzo
- Ciloa, cc90 - Université Montpellier 2, Place E. Bataillon, 34095, Montpellier Cedex 5, France
| | - Géraldine Ferracci
- Aix-Marseille Université, 13015, Marseille, France.,CNRS, UMR 7286, Plate-Forme de Recherche en Neurosciences PFRN, 13015, Marseille, France
| | - Michel Popoff
- CNR Anaérobies et botulisme, Unité Bactéries anaérobies et toxines. Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, Cedex 15, France
| | - Michael Seagar
- INSERM, UMR_S 1072, 13015, Marseille, France.,Aix-Marseille Université, 13015, Marseille, France
| | - Robert Mamoun
- Ciloa, cc90 - Université Montpellier 2, Place E. Bataillon, 34095, Montpellier Cedex 5, France
| | - Oussama El Far
- INSERM, UMR_S 1072, 13015, Marseille, France. .,Aix-Marseille Université, 13015, Marseille, France.
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9
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Biological toxins of potential bioterrorism risk: Current status of detection and identification technology. Trends Analyt Chem 2016. [DOI: 10.1016/j.trac.2016.05.024] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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10
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Weingart OG, Loessner MJ. Nerve cell-mimicking liposomes as biosensor for botulinum neurotoxin complete physiological activity. Toxicol Appl Pharmacol 2016; 313:16-23. [PMID: 27743862 DOI: 10.1016/j.taap.2016.10.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 09/02/2016] [Accepted: 10/10/2016] [Indexed: 10/20/2022]
Abstract
Botulinum neurotoxins (BoNT) are the most toxic substances known, and their neurotoxic properties and paralysing effects are exploited for medical treatment of a wide spectrum of disorders. To accurately quantify the potency of a pharmaceutical BoNT preparation, its physiological key activities (binding to membrane receptor, translocation, and proteolytic degradation of SNARE proteins) need to be determined. To date, this was only possible using animal models, or, to a limited extent, cell-based assays. We here report a novel in vitro system for BoNT/B analysis, based on nerve-cell mimicking liposomes presenting motoneuronal membrane receptors required for BoNT binding. Following triggered membrane translocation of the toxin's Light Chain, the endopeptidase activity can be quantitatively monitored employing a FRET-based reporter assay within the functionalized liposomes. We were able to detect BoNT/B physiological activity at picomolar concentrations in short time, opening the possibility for future replacement of animal experimentation in pharmaceutical BoNT testing.
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Affiliation(s)
- Oliver G Weingart
- Institute for Food, Nutrition and Health, ETH Zurich, Schmelzbergstrasse 7, CH-8092 Zurich, Switzerland.
| | - Martin J Loessner
- Institute for Food, Nutrition and Health, ETH Zurich, Schmelzbergstrasse 7, CH-8092 Zurich, Switzerland
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Worbs S, Fiebig U, Zeleny R, Schimmel H, Rummel A, Luginbühl W, Dorner BG. Qualitative and Quantitative Detection of Botulinum Neurotoxins from Complex Matrices: Results of the First International Proficiency Test. Toxins (Basel) 2015; 7:4935-66. [PMID: 26703724 PMCID: PMC4690107 DOI: 10.3390/toxins7124857] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 11/03/2015] [Accepted: 11/05/2015] [Indexed: 11/16/2022] Open
Abstract
In the framework of the EU project EQuATox, a first international proficiency test (PT) on the detection and quantification of botulinum neurotoxins (BoNT) was conducted. Sample materials included BoNT serotypes A, B and E spiked into buffer, milk, meat extract and serum. Different methods were applied by the participants combining different principles of detection, identification and quantification. Based on qualitative assays, 95% of all results reported were correct. Successful strategies for BoNT detection were based on a combination of complementary immunological, MS-based and functional methods or on suitable functional in vivo/in vitro approaches (mouse bioassay, hemidiaphragm assay and Endopep-MS assay). Quantification of BoNT/A, BoNT/B and BoNT/E was performed by 48% of participating laboratories. It turned out that precise quantification of BoNT was difficult, resulting in a substantial scatter of quantitative data. This was especially true for results obtained by the mouse bioassay which is currently considered as "gold standard" for BoNT detection. The results clearly demonstrate the urgent need for certified BoNT reference materials and the development of methods replacing animal testing. In this context, the BoNT PT provided the valuable information that both the Endopep-MS assay and the hemidiaphragm assay delivered quantitative results superior to the mouse bioassay.
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Affiliation(s)
- Sylvia Worbs
- Biological Toxins, Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Seestrasse 10, 13353 Berlin, Germany.
| | - Uwe Fiebig
- Biological Toxins, Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Seestrasse 10, 13353 Berlin, Germany.
| | - Reinhard Zeleny
- European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, 2440 Geel, Belgium.
| | - Heinz Schimmel
- European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, 2440 Geel, Belgium.
| | - Andreas Rummel
- toxogen GmbH, Feodor-Lynen-Strasse 35, 30625 Hannover, Germany.
| | | | - Brigitte G Dorner
- Biological Toxins, Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Seestrasse 10, 13353 Berlin, Germany.
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12
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Simon S, Fiebig U, Liu Y, Tierney R, Dano J, Worbs S, Endermann T, Nevers MC, Volland H, Sesardic D, Dorner MB. Recommended Immunological Strategies to Screen for Botulinum Neurotoxin-Containing Samples. Toxins (Basel) 2015; 7:5011-34. [PMID: 26703727 PMCID: PMC4690110 DOI: 10.3390/toxins7124860] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 11/03/2015] [Accepted: 11/04/2015] [Indexed: 12/16/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) cause the life-threatening neurological illness botulism in humans and animals and are divided into seven serotypes (BoNT/A–G), of which serotypes A, B, E, and F cause the disease in humans. BoNTs are classified as “category A” bioterrorism threat agents and are relevant in the context of the Biological Weapons Convention. An international proficiency test (PT) was conducted to evaluate detection, quantification and discrimination capabilities of 23 expert laboratories from the health, food and security areas. Here we describe three immunological strategies that proved to be successful for the detection and quantification of BoNT/A, B, and E considering the restricted sample volume (1 mL) distributed. To analyze the samples qualitatively and quantitatively, the first strategy was based on sensitive immunoenzymatic and immunochromatographic assays for fast qualitative and quantitative analyses. In the second approach, a bead-based suspension array was used for screening followed by conventional ELISA for quantification. In the third approach, an ELISA plate format assay was used for serotype specific immunodetection of BoNT-cleaved substrates, detecting the activity of the light chain, rather than the toxin protein. The results provide guidance for further steps in quality assurance and highlight problems to address in the future.
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Affiliation(s)
- Stéphanie Simon
- CEA Saclay, Institute of Biology and Technologies of Saclay, Laboratory for Immunoanalytical Researches, Gif-sur-Yvette 91191 cedex, France.
| | - Uwe Fiebig
- Biological Toxins, Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Seestrasse 10, 13353 Berlin, Germany.
| | - Yvonne Liu
- Division of Bacteriology, National Institute for Biological Standards and Control, a Centre of Medicines & Healthcare Products Regulatory Agency, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK.
| | - Rob Tierney
- Division of Bacteriology, National Institute for Biological Standards and Control, a Centre of Medicines & Healthcare Products Regulatory Agency, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK.
| | - Julie Dano
- CEA Saclay, Institute of Biology and Technologies of Saclay, Laboratory for Immunoanalytical Researches, Gif-sur-Yvette 91191 cedex, France.
| | - Sylvia Worbs
- Biological Toxins, Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Seestrasse 10, 13353 Berlin, Germany.
| | - Tanja Endermann
- Biological Toxins, Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Seestrasse 10, 13353 Berlin, Germany.
| | - Marie-Claire Nevers
- CEA Saclay, Institute of Biology and Technologies of Saclay, Laboratory for Immunoanalytical Researches, Gif-sur-Yvette 91191 cedex, France.
| | - Hervé Volland
- CEA Saclay, Institute of Biology and Technologies of Saclay, Laboratory for Immunoanalytical Researches, Gif-sur-Yvette 91191 cedex, France.
| | - Dorothea Sesardic
- Division of Bacteriology, National Institute for Biological Standards and Control, a Centre of Medicines & Healthcare Products Regulatory Agency, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK.
| | - Martin B Dorner
- Biological Toxins, Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Seestrasse 10, 13353 Berlin, Germany.
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Lau CY, Zahidi AAA, Liew OW, Ng TW. A direct heating model to overcome the edge effect in microplates. J Pharm Biomed Anal 2014; 102:199-202. [PMID: 25289516 DOI: 10.1016/j.jpba.2014.09.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 09/10/2014] [Accepted: 09/13/2014] [Indexed: 11/25/2022]
Abstract
Array-based tests in a microplate format are complicated by the regional variation in results of the outer against the inner wells of the plate. Analysis of the evaporation mechanics of sessile drops showed that evaporation rate increase with temperature was due to changes in the heat of vaporization, density and diffusion coefficient. In simulations of direct bottom heating of standard microplates, considerable heat transfer via conduction from the side walls was found to be responsible for lower temperatures in the liquid in wells close to the edge. Applying a two temperature heating mode, 304 K at the side compared to 310 K at the bottom, allowed for a more uniform temperature distribution. Transparency microplates were found to inherently possess immunity to the edge effect problem due to the presence of air between the liquid and solid wall.
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Affiliation(s)
- Chun Yat Lau
- Laboratory for Optics and Applied Mechanics, Department of Mechanical & Aerospace Engineering, Monash University, Clayton, Victoria 3800, Australia
| | - Alifa Afiah Ahmad Zahidi
- Laboratory for Optics and Applied Mechanics, Department of Mechanical & Aerospace Engineering, Monash University, Clayton, Victoria 3800, Australia
| | - Oi Wah Liew
- Cardiovascular Research Institute, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Centre for Translational Medicine, 14 Medical Drive, Singapore 117599, Singapore
| | - Tuck Wah Ng
- Laboratory for Optics and Applied Mechanics, Department of Mechanical & Aerospace Engineering, Monash University, Clayton, Victoria 3800, Australia.
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14
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Scribed transparency microplates mounted on a modified standard microplate. Anal Biochem 2014; 458:40-2. [DOI: 10.1016/j.ab.2014.04.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 04/21/2014] [Accepted: 04/24/2014] [Indexed: 11/20/2022]
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15
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Lévêque C, Ferracci G, Maulet Y, Mazuet C, Popoff M, Seagar M, El Far O. Direct biosensor detection of botulinum neurotoxin endopeptidase activity in sera from patients with type A botulism. Biosens Bioelectron 2014; 57:207-12. [DOI: 10.1016/j.bios.2014.02.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 02/06/2014] [Accepted: 02/08/2014] [Indexed: 12/22/2022]
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16
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Dunning FM, Piazza TM, Zeytin FN, Tucker WC. Isolation and quantification of botulinum neurotoxin from complex matrices using the BoTest matrix assays. J Vis Exp 2014. [PMID: 24638074 DOI: 10.3791/51170] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Accurate detection and quantification of botulinum neurotoxin (BoNT) in complex matrices is required for pharmaceutical, environmental, and food sample testing. Rapid BoNT testing of foodstuffs is needed during outbreak forensics, patient diagnosis, and food safety testing while accurate potency testing is required for BoNT-based drug product manufacturing and patient safety. The widely used mouse bioassay for BoNT testing is highly sensitive but lacks the precision and throughput needed for rapid and routine BoNT testing. Furthermore, the bioassay's use of animals has resulted in calls by drug product regulatory authorities and animal-rights proponents in the US and abroad to replace the mouse bioassay for BoNT testing. Several in vitro replacement assays have been developed that work well with purified BoNT in simple buffers, but most have not been shown to be applicable to testing in highly complex matrices. Here, a protocol for the detection of BoNT in complex matrices using the BoTest Matrix assays is presented. The assay consists of three parts: The first part involves preparation of the samples for testing, the second part is an immunoprecipitation step using anti-BoNT antibody-coated paramagnetic beads to purify BoNT from the matrix, and the third part quantifies the isolated BoNT's proteolytic activity using a fluorogenic reporter. The protocol is written for high throughput testing in 96-well plates using both liquid and solid matrices and requires about 2 hr of manual preparation with total assay times of 4-26 hr depending on the sample type, toxin load, and desired sensitivity. Data are presented for BoNT/A testing with phosphate-buffered saline, a drug product, culture supernatant, 2% milk, and fresh tomatoes and includes discussion of critical parameters for assay success.
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17
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A quantitative bifunctional in vitro potency assay for botulinum neurotoxin serotype A. J Pharmacol Toxicol Methods 2014; 69:103-7. [DOI: 10.1016/j.vascn.2013.12.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Revised: 10/21/2013] [Accepted: 12/05/2013] [Indexed: 11/22/2022]
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18
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Diamant E, Lachmi BE, Keren A, Barnea A, Marcus H, Cohen S, David AB, Zichel R. Evaluating the synergistic neutralizing effect of anti-botulinum oligoclonal antibody preparations. PLoS One 2014; 9:e87089. [PMID: 24475231 PMCID: PMC3903612 DOI: 10.1371/journal.pone.0087089] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2013] [Accepted: 12/18/2013] [Indexed: 01/12/2023] Open
Abstract
Botulinum neurotoxins (BoNT) are considered some of the most lethal known substances. There are seven botulinum serotypes, of which types A, B and E cause most human botulism cases. Anti-botulinum polyclonal antibodies (PAbs) are currently used for both detection and treatment of the disease. However, significant improvements in immunoassay specificity and treatment safety may be made using monoclonal antibodies (MAbs). In this study, we present an approach for the simultaneous generation of highly specific and neutralizing MAbs against botulinum serotypes A, B, and E in a single process. The approach relies on immunization of mice with a trivalent mixture of recombinant C-terminal fragment (Hc) of each of the three neurotoxins, followed by a parallel differential robotic hybridoma screening. This strategy enabled the cloning of seven to nine MAbs against each serotype. The majority of the MAbs possessed higher anti-botulinum ELISA titers than anti-botulinum PAbs and had up to five orders of magnitude greater specificity. When tested for their potency in mice, neutralizing MAbs were obtained for all three serotypes and protected against toxin doses of 10 MsLD50-500 MsLD50. A strong synergistic effect of up to 400-fold enhancement in the neutralizing activity was observed when serotype-specific MAbs were combined. Furthermore, the highly protective oligoclonal combinations were as potent as a horse-derived PAb pharmaceutical preparation. Interestingly, MAbs that failed to demonstrate individual neutralizing activity were observed to make a significant contribution to the synergistic effect in the oligoclonal preparation. Together, the trivalent immunization strategy and differential screening approach enabled us to generate highly specific MAbs against each of the A, B, and E BoNTs. These new MAbs may possess diagnostic and therapeutic potential.
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Affiliation(s)
- Eran Diamant
- Department of Biotechnology, Israel Institute for Biological Research, Ness Ziona, Israel
| | - Bat-El Lachmi
- Department of Infectious Diseases, Israel Institute for Biological Research, Ness Ziona, Israel
| | - Adi Keren
- Department of Biotechnology, Israel Institute for Biological Research, Ness Ziona, Israel
| | - Ada Barnea
- Department of Biotechnology, Israel Institute for Biological Research, Ness Ziona, Israel
| | - Hadar Marcus
- Department of Biotechnology, Israel Institute for Biological Research, Ness Ziona, Israel
| | - Shoshana Cohen
- Department of Biotechnology, Israel Institute for Biological Research, Ness Ziona, Israel
| | - Alon Ben David
- Department of Biotechnology, Israel Institute for Biological Research, Ness Ziona, Israel
| | - Ran Zichel
- Department of Biotechnology, Israel Institute for Biological Research, Ness Ziona, Israel
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19
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Halliwell J, Gwenin C. A label free colorimetric assay for the detection of active botulinum neurotoxin type A by SNAP-25 conjugated colloidal gold. Toxins (Basel) 2013; 5:1381-91. [PMID: 23925142 PMCID: PMC3760041 DOI: 10.3390/toxins5081381] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 07/26/2013] [Accepted: 07/30/2013] [Indexed: 01/09/2023] Open
Abstract
Botulinum neurotoxins are one of the most potent toxins known to man. Current methods of detection involve the quantification of the toxin but do not take into account the percentage of the toxin that is active. At present the assay used for monitoring the activity of the toxin is the mouse bioassay, which is lengthy and has ethical issues due to the use of live animals. This report demonstrates a novel assay that utilises the endopeptidase activity of the toxin to detect Botulinum neurotoxin in a pharmaceutical sample. The cleaving of SNAP-25 is monitored via UV-Visible spectroscopy with a limit of detection of 373 fg/mL and has been further developed into a high throughput method using a microplate reader detecting down to 600 fg/mL of active toxin. The results show clear differences between the toxin product and the placebo, which contains the pharmaceutical excipients human serum albumin and lactose, showing that the assay detects the active form of the toxin.
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Affiliation(s)
| | - Christopher Gwenin
- Author to whom correspondence should be addressed; E-Mail: ; Tel: +44-1248-383-741; Fax: +44-1248-370-528
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20
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Jones RGA, Marks JD. Use of a new functional dual coating (FDC) assay to measure low toxin levels in serum and food samples following an outbreak of human botulism. J Med Microbiol 2013; 62:828-835. [DOI: 10.1099/jmm.0.053124-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Clostridium
botulinum type A toxin is the most prevalent cause of naturally occurring outbreaks of human botulism in the world. The active dichain neurotoxin molecule is composed of a heavy chain (H-chain) of ~100 kDa with the carboxy-terminal end consisting of a receptor-binding (HC) domain, while the amino-terminal (HN) domain is linked by a critical disulfide bond to a light chain (L-chain) of ~50 kDa. Although the mouse bioassay (MBA) is traditionally used to confirm the presence of toxin in serum or food, its sensitivity is insufficient to detect low toxin levels in approximately 30 to 60 % of botulism patients. A novel FDC (functional dual coating) microtitre plate immuno-biochemical assay, which quantifies botulinum toxicity by measuring the HC domain linked with L-chain endopeptidase activity, was modified to allow human serum (lysed or unlysed) to be tested without interference from the matrix, with toxin detection down to 0.03 mouse LD50 per ml serum or 0.13 pg ml–1 using just 100 µl of clinical samples. The assay was specific for type A toxin and could additionally be applied to whole blood and food samples. Low levels of 1 to 2 mouse LD50 per ml serum of type A toxin were quantified for the first time using the modified FDC assay in two severely intoxicated UK patients who required mechanical ventilation and antitoxin. Toxin levels in recovered food sample extracts were also detected and one MBA-negative sample was found to contain 0.32 LD50 per ml extract. The FDC assay provides a real alternative for public health laboratories to unambiguously confirm all cases of type A botulism and, due to its sensitivity, a promising new tool in toxin pharmacokinetic studies.
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Affiliation(s)
- Russell G. A. Jones
- Division of Bacteriology, National Institute for Biological Standards and Control, Health Protection Agency, South Mimms, Hertfordshire, UK
| | - James D. Marks
- Department of Anesthesia, University of California, San Francisco, USA
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21
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Pellett S. Progress in cell based assays for botulinum neurotoxin detection. Curr Top Microbiol Immunol 2013; 364:257-85. [PMID: 23239357 DOI: 10.1007/978-3-642-33570-9_12] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Botulinum neurotoxins (BoNTs) are the most potent human toxins known and the causative agent of botulism, and are widely used as valuable pharmaceuticals. The BoNTs are modular proteins consisting of a heavy chain and a light chain linked by a disulfide bond. Intoxication of neuronal cells by BoNTs is a multi-step process including specific cell binding, endocytosis, conformational change in the endosome, translocation of the enzymatic light chain into the cells cytosol, and SNARE target cleavage. The quantitative and reliable potency determination of fully functional BoNTs produced as active pharmaceutical ingredient (API) requires an assay that considers all steps in the intoxication pathway. The in vivo mouse bioassay has for years been the 'gold standard' assay used for this purpose, but it requires the use of large numbers of mice and thus causes associated costs and ethical concerns. Cell-based assays are currently the only in vitro alternative that detect fully functional BoNTs in a single assay and have been utilized for years for research purposes. Within the last 5 years, several cell-based BoNT detection assays have been developed that are able to quantitatively determine BoNT potency with similar or greater sensitivity than the mouse bioassay. These assays now offer an alternative method for BoNT potency determination. Such quantitative and reliable BoNT potency determination is a crucial step in basic research, in the development of pharmaceutical BoNTs, and in the quantitative detection of neutralizing antibodies.
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Affiliation(s)
- Sabine Pellett
- Department of Bacteriology, University of Wisconsin, Madison, WI 53706, USA.
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22
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Zhang Y, Lou J, Jenko KL, Marks JD, Varnum SM. Simultaneous and sensitive detection of six serotypes of botulinum neurotoxin using enzyme-linked immunosorbent assay-based protein antibody microarrays. Anal Biochem 2012; 430:185-92. [PMID: 22935296 DOI: 10.1016/j.ab.2012.08.021] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 07/27/2012] [Accepted: 08/21/2012] [Indexed: 11/18/2022]
Abstract
Botulinum neurotoxins (BoNTs), produced by Clostridium botulinum, are a group of seven (A-G) immunologically distinct proteins and cause the paralytic disease botulism. These toxins are the most poisonous substances known to humans and are potential bioweapon agents. Therefore, it is necessary to develop highly sensitive assays for the detection of BoNTs in both clinical and environmental samples. In the current study, we have developed an enzyme-linked immunosorbent assay (ELISA)-based protein antibody microarray for the sensitive and simultaneous detection of BoNT serotypes A, B, C, D, E, and F. With engineered high-affinity antibodies, the BoNT assays have sensitivities in buffer ranging from 1.3fM (0.2pg/ml) to 14.7fM (2.2pg/ml). Using clinical and food matrices (serum and milk), the microarray is capable of detecting BoNT serotypes A to F to similar levels as in standard buffer. Cross-reactivity between assays for individual serotype was also analyzed. These simultaneous, rapid, and sensitive assays have the potential to measure botulinum toxins in a high-throughput manner in complex clinical, food, and environmental samples.
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Affiliation(s)
- Yanfeng Zhang
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA
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23
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Sesardic T. Bioassays for evaluation of medical products derived from bacterial toxins. Curr Opin Microbiol 2012; 15:310-6. [PMID: 22651974 DOI: 10.1016/j.mib.2012.05.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 05/14/2012] [Indexed: 12/14/2022]
Abstract
Bioassays play central role in evaluation of biological products and those derived from bacterial toxins often rely exclusively on in vivo models for assurance of safety and potency. This chapter reviews existing regulatory approved methods designed to provide information on potency and safety of complex biological medicines with an insight into strategies considered for alternative procedures.
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Affiliation(s)
- Thea Sesardic
- Division of Bacteriology, National Institute for Biological Standards and Control, South Mimms, Potters Bar, Hertfordshire EN6 3QG, United Kingdom.
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25
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Dorner MB, Schulz KM, Kull S, Dorner BG. Complexity of Botulinum Neurotoxins: Challenges for Detection Technology. Curr Top Microbiol Immunol 2012. [DOI: 10.1007/978-3-662-45790-0_11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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