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Fan Y, Lou J, Tam CC, Wen W, Conrad F, Leal da Silva Alves P, Cheng LW, Garcia-Rodriguez C, Farr-Jones S, Marks JD. A Three-Monoclonal Antibody Combination Potently Neutralizes BoNT/G Toxin in Mice. Toxins (Basel) 2023; 15:toxins15050316. [PMID: 37235351 DOI: 10.3390/toxins15050316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Revised: 04/20/2023] [Accepted: 04/26/2023] [Indexed: 05/28/2023] Open
Abstract
Equine-derived antitoxin (BAT®) is the only treatment for botulism from botulinum neurotoxin serotype G (BoNT/G). BAT® is a foreign protein with potentially severe adverse effects and is not renewable. To develop a safe, more potent, and renewable antitoxin, humanized monoclonal antibodies (mAbs) were generated. Yeast displayed single chain Fv (scFv) libraries were prepared from mice immunized with BoNT/G and BoNT/G domains and screened with BoNT/G using fluorescence-activated cell sorting (FACS). Fourteen scFv-binding BoNT/G were isolated with KD values ranging from 3.86 nM to 103 nM (median KD 20.9 nM). Five mAb-binding non-overlapping epitopes were humanized and affinity matured to create antibodies hu6G6.2, hu6G7.2, hu6G9.1, hu6G10, and hu6G11.2, with IgG KD values ranging from 51 pM to 8 pM. Three IgG combinations completely protected mice challenged with 10,000 LD50s of BoNT/G at a total mAb dose of 6.25 μg per mouse. The mAb combinations have the potential for use in the diagnosis and treatment of botulism due to serotype G and, along with antibody combinations to BoNT/A, B, C, D, E, and F, provide the basis for a fully recombinant heptavalent botulinum antitoxin to replace the legacy equine product.
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Affiliation(s)
- Yongfeng Fan
- Department of Anesthesia and Perioperative Care, University of California, 1001 Potrero Ave., San Francisco, CA 94110, USA
| | - Jianlong Lou
- Department of Anesthesia and Perioperative Care, University of California, 1001 Potrero Ave., San Francisco, CA 94110, USA
| | - Christina C Tam
- Western Regional Research Center, Agricultural Research Station, United States Department of Agriculture, Albany, CA 94710, USA
| | - Weihua Wen
- Department of Anesthesia and Perioperative Care, University of California, 1001 Potrero Ave., San Francisco, CA 94110, USA
| | - Fraser Conrad
- Department of Anesthesia and Perioperative Care, University of California, 1001 Potrero Ave., San Francisco, CA 94110, USA
| | - Priscila Leal da Silva Alves
- Western Regional Research Center, Agricultural Research Station, United States Department of Agriculture, Albany, CA 94710, USA
| | - Luisa W Cheng
- Western Regional Research Center, Agricultural Research Station, United States Department of Agriculture, Albany, CA 94710, USA
| | - Consuelo Garcia-Rodriguez
- Department of Anesthesia and Perioperative Care, University of California, 1001 Potrero Ave., San Francisco, CA 94110, USA
| | - Shauna Farr-Jones
- Department of Anesthesia and Perioperative Care, University of California, 1001 Potrero Ave., San Francisco, CA 94110, USA
| | - James D Marks
- Department of Anesthesia and Perioperative Care, University of California, 1001 Potrero Ave., San Francisco, CA 94110, USA
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Ma X, Li K, Li F, Su J, Meng W, Sun Y, Sun H, Sun J, Yuan Y, Lin Y, Hu S, Xu X, He Z. Tracing Foodborne Botulism Events Caused by Clostridium botulinum in Xinjiang Province, China, Using a Core Genome Sequence Typing Scheme. Microbiol Spectr 2022; 10:e0116422. [PMID: 36377961 PMCID: PMC9769928 DOI: 10.1128/spectrum.01164-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 10/22/2022] [Indexed: 11/16/2022] Open
Abstract
Foodborne botulism is a rare but life-threatening illness resulting from the action of a potent toxin mainly produced by Clostridium botulinum. It grows in an oxygen-deficient environment and is extremely viable in meat and soy products, making it one of the most virulent bacteria. How to track foodborne botulism events quickly and accurately has become a key issue. Here, we investigated two foodborne botulism events that occurred in Xinjiang in 2019 based on whole-genome sequencing and also successfully traced the relationship between clinical and food C. botulinum isolates using whole-genome core gene markers. All 59 isolates were classified as group I strains. Of the strains isolated in this study, 44 were found to be botulinum toxin A(B), and 15 isolates contained only the toxin B locus. Both the toxin A and B gene segments were located on the chromosome and organized in an ha cluster. Antibiotic resistance and virulence factors were also investigated. A set of 329 universal core gene markers were established using C. botulinum strains from a public database. These core gene markers were applied to the published C. botulinum genomes, and three outbreaks were identified. This work demonstrates that universal core gene markers can be used to trace foodborne botulism events, and we hope that our work will facilitate this effort in future. IMPORTANCE In this study, we analyzed 59 foodborne botulism (FB)-related strains isolated in Xinjiang Province, China. Our findings not only reveal the group classification, neurotoxin locus organization, antibiotic resistance and virulence factors of these strains but also establish a set of core gene markers for tracing foodborne botulism events, which was verified using published genomes. These findings indicate that these gene markers might be used as a potential tracing tool for FB events caused by C. botulinum group I strains, which have relatively stable genomic components.
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Affiliation(s)
- Xin Ma
- Center for Disease Control and Prevention of Xinjiang Uygur Autonomous Region, Urumqi, China
| | - Kexin Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- School of Engineering Medicine, Beihang University, Beijing, China
- Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Interdisciplinary Innovation Institute of Medicine and Engineering, Beihang University, Beijing, China
| | - Fang Li
- Center for Disease Control and Prevention of Xinjiang Uygur Autonomous Region, Urumqi, China
| | - Jing Su
- Center for Disease Control and Prevention of Xinjiang Uygur Autonomous Region, Urumqi, China
| | - Weiwei Meng
- Center for Disease Control and Prevention of Xinjiang Uygur Autonomous Region, Urumqi, China
| | - Yanming Sun
- School of Engineering Medicine, Beihang University, Beijing, China
| | - Hui Sun
- State Key Laboratory for Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, Beijing, China
- National Institute for Communicable Diseases Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Jiazheng Sun
- Criminal Investigation School, People's Public Security University of China, Beijing, China
| | - Yonghe Yuan
- Center for Disease Control and Prevention of Xinjiang Uygur Autonomous Region, Urumqi, China
| | - Yujia Lin
- Center for Disease Control and Prevention of Xinjiang Uygur Autonomous Region, Urumqi, China
| | - Songnian Hu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Xuefang Xu
- State Key Laboratory for Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, Beijing, China
- National Institute for Communicable Diseases Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Zilong He
- School of Engineering Medicine, Beihang University, Beijing, China
- Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Interdisciplinary Innovation Institute of Medicine and Engineering, Beihang University, Beijing, China
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Gonzalez-Escalona N, Sharma SK. Closing Clostridium botulinum Group I Genomes Using a Combination of Short- and Long-Reads. Front Microbiol 2020; 11:239. [PMID: 32153532 PMCID: PMC7050642 DOI: 10.3389/fmicb.2020.00239] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 01/31/2020] [Indexed: 11/13/2022] Open
Abstract
Clostridium botulinum is a Gram-positive, spore-forming anaerobic bacterium that produces botulinum neurotoxin (BoNT). Closing their genomes provides information about their neurotoxin clusters' arrangement(s) and their location (e.g., chromosome or plasmid) which cannot be assessed using draft genomes. Therefore, we tested the use of long-read sequencing (nanopore sequencing) in combination with short-read sequencing to close two toxin-producing strains. These genomes could be used by the Public Health Emergency Preparedness and Response staff during botulism outbreaks. The genomes of two toxin-producing C. botulinum strains, one from an environmental sample (83F_CFSAN034202) and the other from a clinical sample (CDC51232_CFSAN034200) were sequenced using MinION and MiSeq devices. The genomes, including the chromosomes and the plasmids, were closed by a combination of long-read and short-read sequencing. They belonged to different C. botulinum sequence types (STs), with 83F belonging to ST4 and CDC51232 to ST7. A whole genome single nucleotide polymorphism (SNP) analysis clustered these two strains with strains in lineage 2 (e.g., 6CDC297) and 4 (e.g., NCTC2916) from Group I, respectively. These two strains were also bivalent strains with the BoNTB and BoNTA4 clusters located in the larger plasmid for CDC51232, and the BoNTB and BoNTA1 clusters located both in the chromosome for 83F. Overall, this study showed the advantage of combining these two sequencing methods to obtain high quality closed C. botulinum genomes that could be used for SNP phylogenies (source tracking) as well as for fast identification of BoNT clusters and their gene arrangements.
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Affiliation(s)
- Narjol Gonzalez-Escalona
- Division of Microbiology, Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD, United States
| | - Shashi K Sharma
- Division of Microbiology, Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD, United States
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Donald S, Elliott M, Gray B, Hornby F, Lewandowska A, Marlin S, Favre-Guilmard C, Périer C, Cornet S, Kalinichev M, Krupp J, Fonfria E. A comparison of biological activity of commercially available purified native botulinum neurotoxin serotypes A1 to F1 in vitro, ex vivo, and in vivo. Pharmacol Res Perspect 2018; 6:e00446. [PMID: 30519475 PMCID: PMC6261930 DOI: 10.1002/prp2.446] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 10/24/2018] [Accepted: 10/25/2018] [Indexed: 01/12/2023] Open
Abstract
Botulinum neurotoxin (BoNT) is a major therapeutic agent. Of seven native BoNT serotypes (A to G), only A and B are currently used in the clinic. Here we compared the potency of commercially available purified native serotypes A1 to F1 across in vitro, ex vivo, and in vivo assays. BoNT potency in vitro was assessed in rat primary cells (target protein cleavage and neurotransmitter release assays) in supraspinal, spinal, and sensory systems. BoNT potency ex vivo was measured in the mouse phrenic nerve hemidiaphragm (PNHD) assay, measuring muscle contractility. In vivo, BoNT-induced muscle relaxation in mice and rats was assessed in the Digit Abduction Score (DAS) test, while effects on body weight (BW) gain were used to assess tolerability. In all assays, all BoNT serotypes were potent toxins, except serotype D1 in vivo which failed to produce significant muscle flaccidity in mice and rats. In rats, all serotypes were well-tolerated, whereas in mice, reductions in BW were detected at high doses. Serotype A1 was the most potent serotype across in vitro, ex vivo, and in vivo assays. The rank order of potency of the serotypes revealed differences among assays. For example, species-specificity was seen for serotype B1, and to a lesser extent for serotype C1. Serotypes F1 and C1, not currently in the clinic, showed preference for sensory over motor models and therefore could be considered for development in conditions involving the somatosensory system.
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Bano L, Drigo I, Tonon E, Pascoletti S, Puiatti C, Anniballi F, Auricchio B, Lista F, Montecucco C, Agnoletti F. Identification and characterization of Clostridium botulinum group III field strains by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS). Anaerobe 2017; 48:126-134. [PMID: 28802703 DOI: 10.1016/j.anaerobe.2017.08.004] [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: 03/24/2017] [Revised: 07/28/2017] [Accepted: 08/07/2017] [Indexed: 10/19/2022]
Abstract
Animal botulism is primarily due to botulinum neurotoxin (BoNT) types C, D or their chimeric variants C/D or D/C, produced by Clostridium botulinum group III, which appears to include the genetically indistinguishable Clostridium haemolyticum and Clostridium novyi. In the present study, we used matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI TOF MS) to identify and characterize 81 BoNT-producing Clostridia isolated in 47 episodes of animal botulism. The instrument's default database, containing no entries for Clostridium botulinum, permitted reliable identification of 26 strains at the genus level. Although supplementation of the database with reference strains enhanced the instrument's ability to identify the neurotoxic strains at the genus level, resolution was not sufficient to recognize field strains at species level. Characterization by MALDI TOF confirmed the well-documented phenotypic and genetic differences between Clostridium botulinum strains of serotypes normally implicated in human botulism (A, B, E, F) and other Clostridium species able to produce BoNTs type C and D. The chimeric and non-chimeric field strains grouped separately. In particular, very low similarity was found between two non-chimeric type C field strains isolated in the same outbreak and the other field strains. This difference was comparable with the differences among the various Clostridia species included in the study. Characterization by MALDI TOF confirmed that BoNT-producing Clostridia isolated from animals are closely related and indistinguishable at the species level from Clostridium haemolyticum and Clostridium novyi reference strains. On the contrary, there seem to be substantial differences among chimeric and some non-chimeric type C strains.
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Affiliation(s)
- Luca Bano
- Diagnostic and Microbiology Veterinary Laboratory, Istituto Zooprofilattico Sperimentale delle Venezie, Villorba di Treviso, Italy.
| | - Ilenia Drigo
- Diagnostic and Microbiology Veterinary Laboratory, Istituto Zooprofilattico Sperimentale delle Venezie, Villorba di Treviso, Italy
| | - Elena Tonon
- Diagnostic and Microbiology Veterinary Laboratory, Istituto Zooprofilattico Sperimentale delle Venezie, Villorba di Treviso, Italy
| | - Simone Pascoletti
- Diagnostic and Microbiology Veterinary Laboratory, Istituto Zooprofilattico Sperimentale delle Venezie, Villorba di Treviso, Italy
| | - Cinzia Puiatti
- Diagnostic and Microbiology Veterinary Laboratory, Istituto Zooprofilattico Sperimentale delle Venezie, Villorba di Treviso, Italy
| | - Fabrizio Anniballi
- National Reference Center for Botulism, Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Roma, Italy
| | - Bruna Auricchio
- National Reference Center for Botulism, Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Roma, Italy
| | - Florigio Lista
- Army Medical and Veterinary Research Center, Roma, Italy
| | - Cesare Montecucco
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Fabrizio Agnoletti
- Diagnostic and Microbiology Veterinary Laboratory, Istituto Zooprofilattico Sperimentale delle Venezie, Villorba di Treviso, Italy
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Kalb SR, Baudys J, Barr JR. Detection of the HA-33 protein in botulinum neurotoxin type G complex by mass spectrometry. BMC Microbiol 2015; 15:227. [PMID: 26494251 PMCID: PMC4619279 DOI: 10.1186/s12866-015-0567-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 10/15/2015] [Indexed: 11/30/2022] Open
Abstract
Background The disease botulism is caused by intoxication with botulinum neurotoxins (BoNTs), extremely toxic proteins which cause paralysis. This neurotoxin is produced by some members of the Clostridium botulinum and closely related species, and is produced as a protein complex consisting of the neurotoxin and neurotoxin-associated proteins (NAPs). There are seven known serotypes of BoNT, A-G, and the composition of the NAPs can differ between these serotypes. It was previously published that the BoNT/G complex consisted of BoNT/G, nontoxic-nonhemagglutinin (NTNH), Hemagglutinin 70 (HA-70), and HA-17, but that HA-33, a component of the protein complex of other serotypes of BoNT, was not found. Methods Components of the BoNT/G complex were first separated by SDS-PAGE, and bands corresponding to components of the complex were digested and analyzed by LC-MS/MS. Results Gel bands were identified with sequence coverages of 91 % for BoNT/G, 91 % for NTNH, 89 % for HA-70, and 88 % for HA-17. Notably, one gel band was also clearly identified as HA-33 with 93 % sequence coverage. Conclusions The BoNT/G complex consists of BoNT/G, NTNH, HA-70, HA-17, and HA-33. These proteins form the progenitor form of BoNT/G, similar to all other HA positive progenitor toxin complexes.
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Affiliation(s)
- Suzanne R Kalb
- Centers for Disease Control and Prevention, National Center for Environmental Health, Division of Laboratory Sciences, 4770 Buford Hwy, NE, Atlanta, GA, 30341, USA.
| | - Jakub Baudys
- Centers for Disease Control and Prevention, National Center for Environmental Health, Division of Laboratory Sciences, 4770 Buford Hwy, NE, Atlanta, GA, 30341, USA.
| | - John R Barr
- Centers for Disease Control and Prevention, National Center for Environmental Health, Division of Laboratory Sciences, 4770 Buford Hwy, NE, Atlanta, GA, 30341, USA.
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Distler U, Kuharev J, Tenzer S. Biomedical applications of ion mobility-enhanced data-independent acquisition-based label-free quantitative proteomics. Expert Rev Proteomics 2014; 11:675-84. [DOI: 10.1586/14789450.2014.971114] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Björnstad K, Tevell Åberg A, Kalb SR, Wang D, Barr JR, Bondesson U, Hedeland M. Validation of the Endopep-MS method for qualitative detection of active botulinum neurotoxins in human and chicken serum. Anal Bioanal Chem 2014; 406:7149-61. [PMID: 25228079 DOI: 10.1007/s00216-014-8170-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 09/04/2014] [Accepted: 09/05/2014] [Indexed: 11/28/2022]
Abstract
Botulinum neurotoxins (BoNTs) are highly toxic proteases produced by anaerobic bacteria. Traditionally, a mouse bioassay (MBA) has been used for detection of BoNTs, but for a long time, laboratories have worked with alternative methods for their detection. One of the most promising in vitro methods is a combination of an enzymatic and mass spectrometric assay called Endopep-MS. However, no comprehensive validation of the method has been presented. The main purpose of this work was to perform a validation for the qualitative analysis of BoNT-A, B, C, C/D, D, D/C, and F in serum. The limit of detection (LOD), selectivity, precision, stability in matrix and solution, and correlation with the MBA were evaluated. The LOD was equal to or even better than that of the MBA for BoNT-A, B, D/C, E, and F. Furthermore, Endopep-MS was for the first time successfully used to differentiate between BoNT-C and D and their mosaics C/D and D/C by different combinations of antibodies and target peptides. In addition, sequential antibody capture was presented as a new way to multiplex the method when only a small sample volume is available. In the comparison with the MBA, all the samples analyzed were positive for BoNT-C/D with both methods. These results indicate that the Endopep-MS method is a valid alternative to the MBA as the gold standard for BoNT detection based on its sensitivity, selectivity, and speed and that it does not require experimental animals.
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Affiliation(s)
- Kristian Björnstad
- Department of Chemistry, Environment and Feed Hygiene, National Veterinary Institute (SVA), 751 89, Uppsala, Sweden
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UPLC–MSE application in disease biomarker discovery: The discoveries in proteomics to metabolomics. Chem Biol Interact 2014; 215:7-16. [DOI: 10.1016/j.cbi.2014.02.014] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2013] [Revised: 02/14/2014] [Accepted: 02/28/2014] [Indexed: 01/05/2023]
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Whole-genome single-nucleotide-polymorphism analysis for discrimination of Clostridium botulinum group I strains. Appl Environ Microbiol 2014; 80:2125-32. [PMID: 24463972 DOI: 10.1128/aem.03934-13] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clostridium botulinum is a genetically diverse Gram-positive bacterium producing extremely potent neurotoxins (botulinum neurotoxins A through G [BoNT/A-G]). The complete genome sequences of three strains harboring only the BoNT/A1 nucleotide sequence are publicly available. Although these strains contain a toxin cluster (HA(+) OrfX(-)) associated with hemagglutinin genes, little is known about the genomes of subtype A1 strains (termed HA(-) OrfX(+)) that lack hemagglutinin genes in the toxin gene cluster. We sequenced the genomes of three BoNT/A1-producing C. botulinum strains: two strains with the HA(+) OrfX(-) cluster (69A and 32A) and one strain with the HA(-) OrfX(+) cluster (CDC297). Whole-genome phylogenic single-nucleotide-polymorphism (SNP) analysis of these strains along with other publicly available C. botulinum group I strains revealed five distinct lineages. Strains 69A and 32A clustered with the C. botulinum type A1 Hall group, and strain CDC297 clustered with the C. botulinum type Ba4 strain 657. This study reports the use of whole-genome SNP sequence analysis for discrimination of C. botulinum group I strains and demonstrates the utility of this analysis in quickly differentiating C. botulinum strains harboring identical toxin gene subtypes. This analysis further supports previous work showing that strains CDC297 and 657 likely evolved from a common ancestor and independently acquired separate BoNT/A1 toxin gene clusters at distinct genomic locations.
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Carter AT, Stringer SC, Webb MD, Peck MW. The type F6 neurotoxin gene cluster locus of group II clostridium botulinum has evolved by successive disruption of two different ancestral precursors. Genome Biol Evol 2013; 5:1032-7. [PMID: 23645598 PMCID: PMC3673618 DOI: 10.1093/gbe/evt068] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Genome sequences of five different Group II (nonproteolytic) Clostridium botulinum type F6 strains were compared at a 50-kb locus containing the neurotoxin gene cluster. A clonal origin for these strains is indicated by the fact that sequences were identical except for strain Eklund 202F, with 10 single-nucleotide polymorphisms and a 15-bp deletion. The essential topB gene encoding topoisomerase III was found to have been split by the apparent insertion of 34.4 kb of foreign DNA (in a similar manner to that in Group II C. botulinum type E where the rarA gene has been disrupted by a neurotoxin gene cluster). The foreign DNA, which includes the intact 13.6-kb type F6 neurotoxin gene cluster, bears not only a newly introduced topB gene but also two nonfunctional botulinum neurotoxin gene remnants, a type B and a type E. This observation combined with the discovery of bacteriophage integrase genes and IS4 elements suggest that several rounds of recombination/horizontal gene transfer have occurred at this locus. The simplest explanation for the current genotype is that the ancestral bacterium, a Group II C. botulinum type B strain, received DNA firstly from a strain containing a type E neurotoxin gene cluster, then from a strain containing a type F6 neurotoxin gene cluster. Each event disrupted the previously functional neurotoxin gene. This degree of successive recombination at one hot spot is without precedent in C. botulinum, and it is also the first description of a Group II C. botulinum genome containing more than one neurotoxin gene sequence.
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Affiliation(s)
- Andrew T Carter
- Department of Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Norwich, United Kingdom.
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Proteomic Analysis and Label-Free Quantification of the Large Clostridium difficile Toxins. INTERNATIONAL JOURNAL OF PROTEOMICS 2013; 2013:293782. [PMID: 24066231 PMCID: PMC3771451 DOI: 10.1155/2013/293782] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 06/23/2013] [Accepted: 06/24/2013] [Indexed: 01/05/2023]
Abstract
Clostridium difficile is the leading cause of antibiotic-associated diarrhea in hospitals worldwide, due to hypervirulent epidemic strains with the ability to produce increased quantities of the large toxins TcdA and TcdB. Unfortunately, accurate quantification of TcdA and TcdB from different toxinotypes using small samples has not yet been reported. In the present study, we quantify C. difficile toxins in <0.1 mL of culture filtrate by quantitative label-free mass spectrometry (MS) using data-independent analysis (MSE). In addition, analyses of both purified TcdA and TcdB as well as a standard culture filtrate were performed using gel-based and gel-independent proteomic platforms. Gel-based proteomic analysis was then used to generate basic information on toxin integrity and provided sequence confirmation. Gel-independent in-solution digestion of both toxins using five different proteolytic enzymes with MS analysis generated broad amino acid sequence coverage (91% for TcdA and 95% for TcdB). Proteomic analysis of a culture filtrate identified a total of 101 proteins, among them TcdA, TcdB, and S-layer proteins.
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Kalb SR, Barr JR. Mass Spectrometric Identification and Differentiation of Botulinum Neurotoxins through Toxin Proteomics. REVIEWS IN ANALYTICAL CHEMISTRY 2013; 32:189-196. [PMID: 26316676 PMCID: PMC4549225 DOI: 10.1515/revac-2013-0013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Botulinum neurotoxins (BoNTs) cause the disease botulism, which can be lethal if untreated. There are seven known serotypes of BoNT, A-G, defined by their response to antisera. Many serotypes are distinguished into differing subtypes based on amino acid sequence and immunogenic properties, and some subtypes are further differentiated into toxin variants. Toxin characterization is important as different types of BoNT can respond differently to medical countermeasures for botulism, and characterization of the toxin can aid in epidemiologic and forensic investigations. Proteomic techniques have been established to determine the serotype, subtype, or toxin variant of BoNT. These techniques involve digestion of the toxin into peptides, tandem mass spectrometric (MS/MS) analysis of the peptides, and database searching to identify the BoNT protein. These techniques demonstrate the capability to detect BoNT and its neurotoxin-associated proteins, and differentiate the toxin from other toxins which are up to 99.9% identical in some cases. This differentiation can be accomplished from toxins present in a complex matrix such as stool, food, or bacterial cultures and no DNA is required.
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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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