Concept: Clostridium botulinum
Botulinum neurotoxins (BoNTs), etiological agents of the life threatening neuroparalytic disease botulism, are the most toxic substances currently known. The potential for the use as bioweapon makes the development of small-molecule inhibitor against these deadly toxins is a top priority. Currently, there are no approved pharmacological treatments for BoNT intoxication. Although an effective vaccine/immunotherapy is available for immuno-prophylaxis but this cannot reverse the effects of toxin inside neurons. A small-molecule pharmacological intervention, especially one that would be effective against the light chain protease, would be highly desirable. Similarity search was carried out from ChemBridge and NSC libraries to the hit (7-(phenyl(8-quinolinylamino)methyl)-8-quinolinol; NSC 84096) to mine its analogs. Several hits obtained were screened for in silico inhibition using AutoDock 4.1 and 19 new molecules selected based on binding energy and Ki. Among these, eleven quinolinol derivatives potently inhibited in vitro endopeptidase activity of botulinum neurotoxin type A light chain (rBoNT/A-LC) on synaptosomes isolated from rat brain which simulate the in vivo system. Five of these inhibitor molecules exhibited IC(50) values ranging from 3.0 nM to 10.0 µM. NSC 84087 is the most potent inhibitor reported so far, found to be a promising lead for therapeutic development, as it exhibits no toxicity, and is able to protect animals from pre and post challenge of botulinum neurotoxin type A (BoNT/A).
Recent reports suggest that botulinum neurotoxin (BoNT) A, which is widely used clinically to inhibit neurotransmission, can spread within networks of neurons to have distal effects, but this remains controversial. Moreover, it is not known whether other members of this toxin family are transferred between neurons. Here, we investigate the potential distal effects of BoNT/A, BoNT/D, and tetanus toxin (TeNT), using central neurons grown in microfluidic devices. Toxins acted upon the neurons that mediated initial entry, but all three toxins were also taken up, via an alternative pathway, into non-acidified organelles that mediated retrograde transport to the somato-dendritic compartment. Toxins were then released into the media, where they entered and exerted their effects upon upstream neurons. These findings directly demonstrate that these agents undergo transcytosis and interneuronal transfer in an active form, resulting in long-distance effects.
The use of glyphosate modifies the environment which stresses the living microorganisms. The aim of the present study was to determine the real impact of glyphosate on potential pathogens and beneficial members of poultry microbiota in vitro. The presented results evidence that the highly pathogenic bacteria as Salmonella Entritidis, Salmonella Gallinarum, Salmonella Typhimurium, Clostridium perfringens and Clostridium botulinum are highly resistant to glyphosate. However, most of beneficial bacteria as Enterococcus faecalis, Enterococcus faecium, Bacillus badius, Bifidobacterium adolescentis and Lactobacillus spp. were found to be moderate to highly susceptible. Also Campylobacter spp. were found to be susceptible to glyphosate. A reduction of beneficial bacteria in the gastrointestinal tract microbiota by ingestion of glyphosate could disturb the normal gut bacterial community. Also, the toxicity of glyphosate to the most prevalent Enterococcus spp. could be a significant predisposing factor that is associated with the increase in C. botulinum-mediated diseases by suppressing the antagonistic effect of these bacteria on clostridia.
Foodborne and intestinal botulism are the most common forms of human botulism; both result from the absorption of botulinum neurotoxin (BoNT) from the digestive tract into the circulation. BoNT is a large protein toxin (approximately 150 kDa), but it is able to pass through the epithelial barrier in the digestive tract. Recent cellular and molecular biology studies have begun to unravel the mechanisms by which this large protein toxin crosses the intestinal epithelial barrier. This review provides an overview of current knowledge relating to the absorption of botulinum toxins (BoNT and BoNT complex) from the gastrointestinal tract, with particular emphasis on the interaction of these toxins with the intestinal epithelial barrier.
Clostridium botulinum neurotoxin (BoNT) is a multidomain protein in which the individual modules work in synchronized cooperative action in order to enter into neurons and inhibit synaptic transmission. The di-chain protein is made up of the ~50 kD light chain and the ~100 kD heavy chain. The HC can be further subdivided into the N-terminal translocation domain (H(N)) and the C-terminal Receptor Binding Domain (H©). BoNT entry into neurons requires the toxin to utilize the host cell’s endocytosis pathway where it exploits the acidic environment of the endosome. Within the endosome the H© triggers the H(N) to change conformation from a soluble protein to a membrane inserted protein-conducting channel in precise timing with LC refolding. The LC must partially unfold to a translocation competent conformation in order to be translocated by the H(N) channel in an N to C terminal direction. Upon completion of translocation, the LC is released from the HC and allowed to interact with its substrate SNARE protein. This article discusses the individual functions of each module as well as the mechanisms by which each domain serves as a chaperone for the others, working in concert to achieve productive intoxication.
Distribution and levels of C. botulinum type E was determined on field sites used by Inuit hunters for butchering seals along the coast of Nunavik. The incidence of C. botulinum type E in shoreline soil along the coast was 0, 50, and 87.5% of samples tested for the Hudson Strait, Hudson Bay, and Ungava Bay regions, respectively. Spores were detected in seawater or coastal rock surfaces from 17.6% of butchering sites, almost all located in southern Ungava Bay. Concentrations of C. botulinum type E along the Ungava Bay coast were significantly higher than the coasts of Hudson Strait and Hudson Bay, with the highest concentrations (270 to 1,800/kg) found near butchering sites located along the mouths of large rivers. The Koksoak River contained high levels of C. botulinum type E, with the highest median concentration (270/kg) found in sediments of the marine portion of the river. C. botulinum type E was found in the intestinal contents (4.4%) and skins (1.4%) of seals. A high genetic biodiversity of C. botulinum type E isolates was observed among the 21 butchering sites and their surroundings along the Nunavik coastline, with 83% of isolates (44/53) yielding distinct PFGE genotypes. Multiple sources of C. botulinum type E may be involved in the contamination of seal meat during butchering, but the risk of contamination appears to be much higher from environmental sources along the shoreline of southern Ungava Bay and the sediments of the Koksoak River.
National Outbreak of Type A Foodborne Botulism Associated with a Widely Distributed Commercially Canned Hot Dog Chili Sauce.
- Clinical infectious diseases : an official publication of the Infectious Diseases Society of America
- Published over 5 years ago
Background. On July 7 and 11, 2007, respectively, health officials in Texas and Indiana reported 4 possible cases of type A foodborne botulism to the US Centers for Disease Control and Prevention. Foodborne botulism is a rare and sometimes fatal illness caused by consuming foods containing botulinum neurotoxin.Methods. Investigators reviewed patients' medical charts and food histories. Clinical specimens and food samples were tested for botulinum toxin and neurotoxin-producing Clostridium spp. Investigators conducted inspections of the cannery that produced the implicated product.Results. Eight confirmed outbreak associated cases were identified from Indiana (2), Texas (3), and Ohio (3). Botulinum toxin type A was identified in leftover chili sauce consumed by the Indiana patients and one of the Ohio patients. Cannery inspectors found violations of federal canned-food regulations that could have led to survival of C. botulinum spores during sterilization. The company recalled 39 million cans of chili. Following the outbreak, the US Food and Drug Administration inspected other canneries with similar canning systems and issued warnings to the industry about the danger of C. botulinum and the importance of compliance with canned food manufacturing regulations.Conclusion. Commercially produced hot dog chili sauce caused these cases of type A botulism. This is the first US foodborne botulism outbreak involving a commercial cannery in more than 30 years. Sharing of epidemiologic and laboratory findings allowed for the rapid identification of implicated food items and swift removal of potentially deadly products from the market by US food regulatory authorities.
- Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia
- Published about 5 years ago
Painful legs moving toes (PLMT) is a rare disorder characterized by an often-severe painful sensation in the legs associated with involuntary movement of the toes. The treatment can be challenging given the poor response to pharmacotherapy. We present a patient with PLMT who obtained substantial benefit in both pain and severity of involuntary movement with botulinum toxin type A injections for more than 3years.
- Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.]
- Published over 5 years ago
Because more botulinum toxin (BoNT) preparations have become available worldwide, there is a clinical need to compare the pharmacologic profiles of these products.
Botulinum neurotoxins (BoNTs) are produced by Clostridium botulinum and cause the fatal disease botulism, a flaccid paralysis of the muscle. BoNTs are released together with several auxiliary proteins as progenitor toxin complexes (PTCs) to become highly potent oral poisons. Here, we report the structure of a ∼760 kDa 14-subunit large PTC of serotype A (L-PTC/A) and reveal insight into its absorption mechanism. Using a combination of X-ray crystallography, electron microscopy, and functional studies, we found that L-PTC/A consists of two structurally and functionally independent sub-complexes. A hetero-dimeric 290 kDa complex protects BoNT, while a hetero-dodecameric 470 kDa complex facilitates its absorption in the harsh environment of the gastrointestinal tract. BoNT absorption is mediated by nine glycan-binding sites on the dodecameric sub-complex that forms multivalent interactions with carbohydrate receptors on intestinal epithelial cells. We identified monosaccharides that blocked oral BoNT intoxication in mice, which suggests a new strategy for the development of preventive countermeasures for BoNTs based on carbohydrate receptor mimicry.