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Title: Piggybacking on the cholera toxin : using cholera toxin B chain for the targeted delivery of proteins to motor neurones
Author: Balmforth, Matthew Royce
ISNI:       0000 0004 7230 154X
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2017
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Full text unavailable from EThOS. Thesis embargoed until 01 May 2023
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A significant unmet need exists for the delivery of biologics to the central nervous system for the treatment and understanding of neurodegenerative diseases. Naturally occurring toxoids such as the non-toxic B subunit of the cholera toxin have been considered as tools to meet this need. However, due to the complexity of tethering macromolecular drugs to toxins, and the inherent dangers of working with large quantities of recombinant toxin, no such route has been successfully exploited. Developing a method where toxoid and drug can be assembled immediately prior to administration could therefore be extremely useful. Using phage-display, two cholera toxin-binding antibody mimetics (Affimers) were identified that non-covalently associate with the non-GM1 binding face of the cholera toxin B subunit (CTB). The two unique interactions were characterised using a range of techniques to dissect the Affimer-CTB assembly process. Internalisation of the complex was demonstrated in tissue culture, and the system was used to deliver GFP to mammalian cells. Finally, the complex was shown to be successfully internalised into the motor neurones of the brainstem in a mouse model. A second route to modular assembly of a protein delivery system was also explored. By using a high affinity peptide staple, a cholergenoid-botulinum toxin chimera was produced that could be assembled in vitro and used to deliver the functional catalytic domain of botulinum neurotoxin to cultured neuronal cells.
Supervisor: Turnbull, W. Bruce ; Webb, Mike E. ; Deuchars, Jim Sponsor: Wellcome Trust
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available