scholarly journals RetargetingClostridium difficileToxin B to Neuronal Cells as a Potential Vehicle for Cytosolic Delivery of Therapeutic Biomolecules to Treat Botulism

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Greice Krautz-Peterson ◽  
Yongrong Zhang ◽  
Kevin Chen ◽  
George A. Oyler ◽  
Hanping Feng ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
Neuronal Cells ◽  
Vero Cells ◽  
Receptor Binding Domain ◽  
Wild Type ◽  
Delivery Vehicle ◽  
Toxin B ◽  
Cytosolic Delivery ◽  
Botulinum Neurotoxins ◽  
Neuronal Delivery

Botulinum neurotoxins (BoNTs) deliver a protease to neurons which can cause a flaccid paralysis called botulism. Development of botulism antidotes will require neuronal delivery of agents that inhibit or destroy the BoNT protease. Here, we investigated the potential of engineeringClostridium difficiletoxin B (TcdB) as a neuronal delivery vehicle by testing two recombinant TcdB chimeras. For AGT-TcdB chimera, an alkyltransferase (AGT) was appended to the N-terminal glucosyltransferase (GT) of TcdB. Recombinant AGT-TcdB had alkyltransferase activity, and the chimera was nearly as toxic to Vero cells as wild-type TcdB, suggesting efficient cytosolic delivery of the AGT/GT fusion. For AGT-TcdB-BoNT/A-Hc, the receptor-binding domain (RBD) of TcdB was replaced by the equivalent RBD from BoNT/A (BoNT/A-Hc). AGT-TcdB-BoNT/A-Hc was >25-fold more toxic to neuronal cells and >25-fold less toxic to Vero cells than AGT-TcdB. Thus, TcdB can be engineered for cytosolic delivery of biomolecules and improved targeting of neuronal cells.

scholarly journals Heparin Inhibits Cellular Invasion by SARS-CoV-2: Structural Dependence of the Interaction of the Spike S1 Receptor-Binding Domain with Heparin

2020 ◽  
Vol 120 (12) ◽  
pp. 1700-1715
Author(s):  
Courtney J. Mycroft-West ◽  
Dunhao Su ◽  
Isabel Pagani ◽  
Timothy R. Rudd ◽  
Stefano Elli ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Structural Changes ◽  
Rapid Development ◽  
Antiviral Agents ◽  
Vero Cells ◽  
Binding Domain ◽  
Microbial Pathogens ◽  
Minimum Size ◽  
Structural Basis ◽  
Receptor Binding Domain

AbstractThe dependence of development and homeostasis in animals on the interaction of hundreds of extracellular regulatory proteins with the peri- and extracellular glycosaminoglycan heparan sulfate (HS) is exploited by many microbial pathogens as a means of adherence and invasion. Heparin, a widely used anticoagulant drug, is structurally similar to HS and is a common experimental proxy. Exogenous heparin prevents infection by a range of viruses, including S-associated coronavirus isolate HSR1. Here, we show that heparin inhibits severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) invasion of Vero cells by up to 80% at doses achievable through prophylaxis and, particularly relevant, within the range deliverable by nebulisation. Surface plasmon resonance and circular dichroism spectroscopy demonstrate that heparin and enoxaparin, a low-molecular-weight heparin which is a clinical anticoagulant, bind and induce a conformational change in the spike (S1) protein receptor-binding domain (S1 RBD) of SARS-CoV-2. A library of heparin derivatives and size-defined fragments were used to probe the structural basis of this interaction. Binding to the RBD is more strongly dependent on the presence of 2-O or 6-O sulfate groups than on N-sulfation and a hexasaccharide is the minimum size required for secondary structural changes to be induced in the RBD. It is likely that inhibition of viral infection arises from an overlap between the binding sites of heparin/HS on S1 RBD and that of the angiotensin-converting enzyme 2. The results suggest a route for the rapid development of a first-line therapeutic by repurposing heparin and its derivatives as antiviral agents against SARS-CoV-2 and other members of the Coronaviridae.

scholarly journals Infection with Toxin A-Negative, Toxin B-Negative, Binary Toxin-Positive Clostridium difficile in a Young Patient with Ulcerative Colitis

2015 ◽  
Vol 53 (11) ◽  
pp. 3702-3704 ◽  
Author(s):  
Grace O. Androga ◽  
Julie Hart ◽  
Niki F. Foster ◽  
Adrian Charles ◽  
David Forbes ◽  
...  
Keyword(s):  
Ulcerative Colitis ◽  
Clostridium Difficile ◽  
Young Patient ◽  
Diagnostic Methods ◽  
Binary Toxin ◽  
Toxin A ◽  
Toxin B ◽  
Content Type ◽  
Severe Diarrhea ◽  
Clinically Significant

Large clostridial toxin-negative, binary toxin-positive (A−B−CDT+) strains ofClostridium difficileare almost never associated with clinically significantC. difficileinfection (CDI), possibly because such strains are not detected by most diagnostic methods. We report the isolation of an A−B−CDT+ribotype 033 (RT033) strain ofC. difficilefrom a young patient with ulcerative colitis and severe diarrhea.

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