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Brin MF, Nelson M, Ashourian N, Brideau-Andersen A, Maltman J. Update on Non-Interchangeability of Botulinum Neurotoxin Products. Toxins (Basel) 2024; 16:266. [PMID: 38922160 PMCID: PMC11209304 DOI: 10.3390/toxins16060266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Revised: 06/01/2024] [Accepted: 06/05/2024] [Indexed: 06/27/2024] Open
Abstract
The growing use of botulinum neurotoxins (BoNTs) for medical and aesthetic purposes has led to the development and marketing of an increasing number of BoNT products. Given that BoNTs are biological medications, their characteristics are heavily influenced by their manufacturing methods, leading to unique products with distinct clinical characteristics. The manufacturing and formulation processes for each BoNT are proprietary, including the potency determination of reference standards and other features of the assays used to measure unit potency. As a result of these differences, units of BoNT products are not interchangeable or convertible using dose ratios. The intrinsic, product-level differences among BoNTs are compounded by differences in the injected tissues, which are innervated by different nerve fiber types (e.g., motor, sensory, and/or autonomic nerves) and require unique dosing and injection sites that are particularly evident when treating complex therapeutic and aesthetic conditions. It is also difficult to compare across studies due to inherent differences in patient populations and trial methods, necessitating attention to study details underlying each outcome reported. Ultimately, each BoNT possesses a unique clinical profile for which unit doses and injection paradigms must be determined individually for each indication. This practice will help minimize unexpected adverse events and maximize efficacy, duration, and patient satisfaction. With this approach, BoNT is poised to continue as a unique tool for achieving individual goals for an increasing number of medical and aesthetic indications.
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Affiliation(s)
- Mitchell F. Brin
- AbbVie/Allergan Aesthetics, Irvine, CA 92612, USA; (A.B.-A.); (J.M.)
- Department of Neurology, University of California, Irvine, CA 92697, USA
| | | | | | | | - John Maltman
- AbbVie/Allergan Aesthetics, Irvine, CA 92612, USA; (A.B.-A.); (J.M.)
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Ambrin G, Cai S, Singh BR. Critical analysis in the advancement of cell-based assays for botulinum neurotoxin. Crit Rev Microbiol 2023; 49:1-17. [PMID: 35212259 DOI: 10.1080/1040841x.2022.2035315] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The study on botulinum neurotoxins (BoNTs) has rapidly evolved for their structure and functions as opposed to them being poisons or cures. Since their discoveries, the scientific community has come a long way in understanding BoNTs' structure and biological activity. Given its current application as a tool for understanding neurocellular activity and as a drug against over 800 neurological disorders, relevant and sensitive assays have become critical for biochemical, physiological, and pharmacological studies. The natural entry of the toxin being ingestion, it has also become important to examine its mechanism while crossing the epithelial cell barrier. Several techniques and methodologies have been developed, for its entry, pharmacokinetics, and biological activity for identification, and drug efficacy both in vivo and in vitro conditions. However, each of them presents its own challenges. The cell-based assay is a platform that exceeds the sensitivity of mouse bioassay while encompassing all the steps of intoxication including cell binding, transcytosis, endocytosis, translocation and proteolytic activity. In this article we review in detail both the neuronal and nonneuronal based cellular interaction of BoNT involving its transportation, and interaction with the targeted cells, and intracellular activities.
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Affiliation(s)
- Ghuncha Ambrin
- Department of Biomedical Engineering and Biotechnology, University of Massachusetts, Dartmouth, MA, USA.,Department of Chemistry and Biochemistry, University of Massachusetts, Dartmouth, MA, USA
| | - Shuowei Cai
- Department of Chemistry and Biochemistry, University of Massachusetts, Dartmouth, MA, USA
| | - Bal Ram Singh
- Institute of Advanced Sciences, Botulinum Research Center, Dartmouth, MA, USA
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Real-World Dosing of OnabotulinumtoxinA and IncobotulinumtoxinA for Cervical Dystonia and Blepharospasm: Results from TRUDOSE and TRUDOSE II. Toxins (Basel) 2021; 13:toxins13070488. [PMID: 34357959 PMCID: PMC8310174 DOI: 10.3390/toxins13070488] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 07/02/2021] [Accepted: 07/04/2021] [Indexed: 11/17/2022] Open
Abstract
The real-world use of onabotulinumtoxinA and incobotulinumtoxinA for cervical dystonia and blepharospasm treatment was assessed in two separate retrospective studies using identical protocols (TRUDOSE and TRUDOSE II). The studies were conducted in Mexico, Norway, and United Kingdom and designed to evaluate dose utilization of the two botulinum toxins in clinical practice. Eighty-three patients treated with both onabotulinumtoxinA and incobotulinumtoxinA for ≥2 years for each botulinum toxin were included, (52, cervical dystonia; 31, blepharospasm). All patients switched from onabotulinumtoxinA to incobotulinumtoxinA for administrative/financial reasons. A range of dose ratios (incobotulinumtoxinA to onabotulinumtoxinA) was reported; with the majority of dose ratios being >1. The mean dose ratio was >1 regardless of the study site or underlying clinical condition. The inter-injection interval was significantly longer for onabotulinumtoxinA versus incobotulinumtoxinA when assessed for all patients (15.5 vs. 14.3 weeks; p = 0.006), resulting in fewer onabotulinumtoxinA treatments over the study time period. Consistent with product labeling, no single fixed-dose ratio exists between incobotulinumtoxinA and onabotulinumtoxinA. The dosage of each should be individualized based on patient needs and used as per product labeling. These real-world utilization data may have pharmacoeconomic implications.
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Pellett S, Tepp WH, Johnson EA. Critical Analysis of Neuronal Cell and the Mouse Bioassay for Detection of Botulinum Neurotoxins. Toxins (Basel) 2019; 11:E713. [PMID: 31817843 PMCID: PMC6950160 DOI: 10.3390/toxins11120713] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 11/12/2019] [Accepted: 11/22/2019] [Indexed: 12/14/2022] Open
Abstract
Botulinum Neurotoxins (BoNTs) are a large protein family that includes the most potent neurotoxins known to humankind. BoNTs delivered locally in humans at low doses are widely used pharmaceuticals. Reliable and quantitative detection of BoNTs is of paramount importance for the clinical diagnosis of botulism, basic research, drug development, potency determination, and detection in clinical, environmental, and food samples. Ideally, a definitive assay for BoNT should reflect the activity of each of the four steps in nerve intoxication. The in vivo mouse bioassay (MBA) is the 'gold standard' for the detection of BoNTs. The MBA is sensitive, robust, semi-quantitative, and reliable within its sensitivity limits. Potential drawbacks with the MBA include assay-to-assay potency variations, especially between laboratories, and false positives or negatives. These limitations can be largely avoided by careful planning and performance. Another detection method that has gained importance in recent years for research and potency determination of pharmaceutical BoNTs is cell-based assays, as these assays can be highly sensitive, quantitative, human-specific, and detect fully functional holotoxins at physiologically relevant concentrations. A myriad of other in vitro BoNT detection methods exist. This review focuses on critical factors and assay limitations of the mouse bioassay and cell-based assays for BoNT detection.
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Affiliation(s)
| | | | - Eric A. Johnson
- Department of Bacteriology, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA; (S.P.); (W.H.T.)
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Pellett S. Learning from the past: historical aspects of bacterial toxins as pharmaceuticals. Curr Opin Microbiol 2012; 15:292-9. [PMID: 22651975 DOI: 10.1016/j.mib.2012.05.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 05/10/2012] [Indexed: 12/19/2022]
Abstract
Botulinum neurotoxins are the most poisonous substances known to humankind, but also are the bacterial toxins most frequently used as pharmaceuticals to benefit humans. The discovery of botulinum toxins and development into a useful drug is unique and fascinating, dating back to the early 19th century, when Justinus Kerner first recognized that botulism was caused by a biological toxin and suggested its use for medicinal purposes. This was translated into reality in 1980, when Alan Scott for the first time used the toxins to successfully treat strabismus. Now a subset of botulinum toxins are widely used for cosmetic applications, treatment of various movement disorders, pain and many other syndromes, and further developments using other botulinum toxins or recombinant molecules engineered from subdomains are promising.
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Affiliation(s)
- Sabine Pellett
- Department of Bacteriology, University of Wisconsin, Madison, Madison, WI 53706, USA.
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Brin MF, Tan K, Gallagher C. Differences in botulinum toxins: time to end the confusion. J COSMET LASER THER 2009; 11:180-1. [PMID: 19626521 DOI: 10.1080/14764170903137121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Pearce LB, First ER, MacCallum RD, Gupta A. Pharmacologic characterization of botulinum toxin for basic science and medicine. Toxicon 1997; 35:1373-412. [PMID: 9403963 DOI: 10.1016/s0041-0101(96)00180-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The use of Botulinum neurotoxin (BoNT) is increasing in both clinical and basic science. Clinically, intramuscular injection of nanogram quantities of BoNT is fast becoming the treatment of choice for a spectrum of disorders including movement disorders such as torticollis, blepharospasm, Meige Disease, and hemifacial spasm (Borodic et al., 1991, 1994a; Jankovic and Brin, 1991; Clarke, 1992). Neuroscientists are using BoNTs as tools to develop a better understanding of the mechanisms underlying the neurotransmitter release process. Consequently, our ability to accurately and reliably quantify the biologic activity of botulinum toxin has become more important than ever. The accurate measurement of the pharmacologic activity of BoNTs has become somewhat problematic with the most significant problems occurring with the clinical use of the toxins. The biologic activity of BoNTs has been measured using a variety of techniques including assessment of whole animal responses to in vitro effects on neurotransmitter release. The purpose of this review is to examine the approaches employed to characterize, quantify and investigate the actions of the BoNTs and to provide a guide to aid investigators in determining which of these methods is most appropriate for their particular application or use.
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Affiliation(s)
- L B Pearce
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, MA 02118, USA
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Abstract
The type A neurotoxin produced by Clostridium botulinum is a potent neuromuscular blocking agent which causes paralysis by preventing the release of neurotransmitter from motor neurons. This property has resulted in the use of the toxin in the treatment of a number of neuromuscular diseases involving muscle spasms. At present, the only recognised assay to estimate accurately the potency of botulinum toxin in clinical preparations is bioassay, in which lethality is used as the endpoint. Such bioassay is inherently variable and large interlaboratory variability has been reported, highlighting problems for standardisation of activity in the absence of any commonly used reference preparation. In the present study, we have confirmed that many different assay conditions can affect potency estimates of clinical formulations of type A botulinum toxin. Further, our studies indicate that different preparations, because of their unique formulation and stability, are differentially affected by some of these assay conditions and that these differences might well contribute to the differences observed in their clinical use.
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Affiliation(s)
- K Mclellan
- Division of Bacteriology, National Institute for Biological Standards and Control, Potters Bar, Hertfordshire, U.K
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Sesardic D, McLellan K, Ekong TA, Das RG. Refinement and validation of an alternative bioassay for potency testing of therapeutic botulinum type A toxin. PHARMACOLOGY & TOXICOLOGY 1996; 78:283-8. [PMID: 8737961 DOI: 10.1111/j.1600-0773.1996.tb01376.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The type A neurotoxin produced by Clostridium botulinum is a potent neuromuscular blocking agent which causes paralysis by preventing the release of neurotransmitter from motor neurones. This property has led to the use of the toxin in the treatment of a number of neuromuscular diseases involving muscle spasms. At present, the only recognised assay with the specificity and sensitivity to estimate accurately the potency of botulinum toxin in clinical preparations is bioassay, in which lethality is used as the end point. Refinement of this assay, with respect to the end point, was explored on the basis of the development of flaccid paralysis of muscles following subcutaneous injection of the toxin at the inguinocrural region. Potency estimates, relative to in house reference preparations, for different therapeutic preparations obtained using flaccid paralysis as a scored response gave excellent agreement with estimates obtained in independent assay using the currently required control method. This study demonstrates that an alternative, more humane bioassay for potency testing of clostridia neurotoxins gives valid estimates equivalent to those currently in use.
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Affiliation(s)
- D Sesardic
- Division of Bacteriology, National Institute for Biological Standards and Control, Potters Bar, Hertfordshire, UK
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Patterson-Curtis SI, Johnson EA. Regulation of neurotoxin and protease formation in Clostridium botulinum Okra B and Hall A by arginine. Appl Environ Microbiol 1989; 55:1544-8. [PMID: 2669631 PMCID: PMC202901 DOI: 10.1128/aem.55.6.1544-1548.1989] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Supplementation of a minimal medium with high levels of arginine (20 g/liter) markedly decreased neurotoxin titers and protease activities in cultures of Clostridium botulinum Okra B and Hall A. Nitrogenous nutrients that are known to be derived from arginine, including proline, glutamate, and ammonia, also decreased protease and toxin but less so than did arginine. Proteases synthesized during growth were rapidly inactivated after growth stopped in media containing high levels of arginine. Separation of extracellular proteins by electrophoresis and immunoblots with antibodies to toxin showed that the decrease in toxin titers in media containing high levels of arginine was caused by both reduced synthesis of protoxin and impaired proteolytic activation. In contrast, certain other nutritional conditions stimulated protease and toxin formation in C. botulinum and counteracted the repression by arginine. Supplementation of the minimal medium with casein or casein hydrolysates increased protease activities and toxin titers. Casein supplementation of a medium containing high levels of arginine prevented protease inactivation. High levels of glucose (50 g/liter) also delayed the inactivation of proteases in both the minimal medium and a medium containing high levels of arginine. These observations suggest that the availability of nitrogen and energy sources, particularly arginine, affects the production and proteolytic processing of toxins and proteases in C. botulinum.
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Affiliation(s)
- S I Patterson-Curtis
- Department of Food Microbiology and Toxicology, University of Wisconsin, Madison 53706
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Whitmer ME, Johnson EA. Development of improved defined media for Clostridium botulinum serotypes A, B, and E. Appl Environ Microbiol 1988; 54:753-9. [PMID: 3288120 PMCID: PMC202536 DOI: 10.1128/aem.54.3.753-759.1988] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The minimal nutritional growth requirements were determined for strains Okra B and Iwanai E, which are representatives of groups I and II, respectively, of Clostridium botulinum. These type B and E strains differed considerably in their nutrient requirements. The organic growth factors required in high concentrations by the Okra B strain (group I) were arginine and phenylalanine. Low concentrations (less than or equal to 0.1 g/liter) of eight amino acids (methionine, leucine, valine, isoleucine, glycine, histidine, tryptophan, and tyrosine) and of five vitamins (pyridoxamine, p-aminobenzoic acid, biotin, nicotinic acid, and thiamine) were also essential for biosynthesis. The 10 required amino acids could be replaced by intact protein of known composition by virtue of the bacterium's ability to synthesize proteases. Glucose or other carbohydrates were not essential for Okra B, although they did stimulate growth. Quantitatively, the most essential nutrients for Okra B were arginine and phenylalanine. In contrast, the nonproteolytic strain, Iwanai E (group II), did not require either arginine or phenylalanine. It required glucose or another carbohydrate energy source for growth and did not utilize arginine or intact protein as a substitute source of energy. Iwanai E utilized ammonia as a nitrogen source, although growth was stimulated significantly by organic nitrogenous nutrients, especially glutamate and asparagine. Iwanai E also required biosynthesis levels of seven amino acids (histidine, isoleucine, leucine, tryptophan, tyrosine, valine, and serine), adenine, and six vitamins (biotin, thiamine, pyridoxamine, folic acid, choline, and nicotinamide). Calcium pantothenate also stimulated growth. On the basis of the nutritional requirements, chemically defined minimal media have been constructed for C. botulinum serotypes A, B, E, and F (proteolytic).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M E Whitmer
- Department of Food Microbiology and Toxicology, University of Wisconsin, Madison 53706
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Mayorga LS, de Centorbi OP, de Milan CC, Gimenez DF. Rapid in vivo assay method for type G botulinal toxin. ZENTRALBLATT FUR BAKTERIOLOGIE, MIKROBIOLOGIE, UND HYGIENE. SERIES A, MEDICAL MICROBIOLOGY, INFECTIOUS DISEASES, VIROLOGY, PARASITOLOGY 1987; 264:78-83. [PMID: 3307234 DOI: 10.1016/s0176-6724(87)80126-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The survival time (ST) dose-response curve for Clostridium botulinum type G toxin was determined in mice and evaluated as a rapid assay method. As it occurs with other botulinal toxin types, the results showed a linear relationship between the logarithm of the injected dose and the logarithm of ST. The slope of the ST dose-response curve for type G toxin differed significantly from those for type A or subtype Af toxins. This parameter was altered when trypsin-activated type G toxin was used. The ST dose-response curve was rather stable. This in vivo assay method could be applied for the estimation of the potency of G toxin preparations in a short time using only some few mice.
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Scott AB. Botulinum toxin injection of eye muscles to correct strabismus. TRANSACTIONS OF THE AMERICAN OPHTHALMOLOGICAL SOCIETY 1981; 79:734-70. [PMID: 7043872 PMCID: PMC1312202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
One hundred thirty-two doses of botulinum A toxin were injected into 42 humans. The effect on horizontal strabismus was uniformly beneficial, and effect lasting up to 411 days since the last injection was documented. The effect in vertical strabismus and lid retraction was beneficial, but less strongly so. No systemic effect or local complications were encountered except for effect on adjacent muscles. The drug appears to be a safe and useful therapy for strabismus.
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Abstract
Two Clostridium botulinum type A toxic fractions, named large (L) and medium (M) toxins, were eluted from Sephadex G-200. Sucrose density gradient centrifugation resolved L toxin (2.5 X 10(8) to 3.0 X 10(8) mean lethal doses per mg of N) into two fractions, 19S and 16S. The same procedure performed at pH 8resolved it into three fractions; the heavier two were both nontoxic and hemagglutinin positive, and the lightest on (7S) was toxic. M toxin (12S) (4.5 X 10(8) to 5.0 X 10(8) mean lethal doses per mg of N) was homogeneous in electrophoresis and centrifugation at pH 6. The latter procedure performed at pH 8 dmonstrated that it dissociated into uniform 7S components. The nontoxic component of M toxin was free from hemagglutinin. M toxin alone was demonstrated in culture by sucrose density gradient centrifugation at pH 6. Dialysis of the culture supernatant resulted in partial formation of 16S toxin. Centrifugation of the crystalline toxin in 1 MNaCl demonstrated 16S toxin only. The toxic components of L, M, and crystalline toxins were antigenically identical. The nontoxic components of the crystalline and L toxins, consisting of two distinct antigens, were antigenically identical; that of M toxin was identical with one of these two antigens.
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The Toxins of Clostridium botulinum. ACTA ACUST UNITED AC 1974. [DOI: 10.1016/b978-0-12-107605-4.50010-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Das Gupta BR, Sugiyama H. Role of a protease in natural activation of Clostridium botulinum neurotoxin. Infect Immun 1972; 6:587-90. [PMID: 4564288 PMCID: PMC422579 DOI: 10.1128/iai.6.4.587-590.1972] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
All tested proteolytic Clostridium botulinum type A, B, and F strains and certain non-proteolytic B and F cultures produced a protease having trypsin-like substrate specificity; none of the tested type E (non-proteolytic) strains produced the enzyme. Progenitor toxin (toxic form whose specific toxicity is increased by treatment with trypsin) was found in culture fluid concentrates of all strains not producing the protease; it was also present in some concentrates that had the enzyme. Activation of highly purified type E progenitor toxin (molecular weight 150,000) by essentially pure protease from a proteolytic type B culture was always less than that obtained with trypsin. The product of the type E progenitor toxin-protease reaction increased in toxicity when further treated with trypsin. Results suggest that at least two bonds are cleaved by trypsin during activation of type E progenitor toxin to toxin (form manifesting maximal possible specific toxicity). Natural activation of progenitor toxin of proteolytic strains may also involve cleavage of more than one bond.
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Abstract
It was previously postulated, based on indirect evidence, that Clostridium botulinum type B produces neurotoxin which is initially of low toxicity but which then becomes activated to highly toxic form by the action of an endogenous enzyme(s). The first direct in vitro experimental evidence in support of this hypothesis is presented here. The mildly active toxin (progenitor toxin) produced by C. botulinum type B (Lamanna) was isolated from the filtrate of a 24-hr culture and partially purified chromatographically. An enzyme that activates the progenitor toxin was also isolated from the filtrate of a 96-hr culture and purified 200-fold. The enzyme hydrolyzes synthetic substrates of trypsin but not of chymotrypsin.
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Lamanna C, Sakaguchi G. Botulinal toxins and the problem of nomenclature of simple toxins. BACTERIOLOGICAL REVIEWS 1971; 35:242-9. [PMID: 5114966 PMCID: PMC378388 DOI: 10.1128/br.35.3.242-249.1971] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Knox J, Brown WP, Spero L. The role of sulfhydryl groups in the activity of type A botulinum toxin. BIOCHIMICA ET BIOPHYSICA ACTA 1970; 214:350-4. [PMID: 4925645 DOI: 10.1016/0005-2795(70)90012-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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