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Novel strategiesfor the characterisation and diagnosis of snakebite envenomation

Williams, H. F. (2019) Novel strategiesfor the characterisation and diagnosis of snakebite envenomation. PhD thesis, University of Reading

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Abstract/Summary

Globally, snakebite envenoming (SBE) kills in excess of 100,000peopleannually andcauses sequalaeto over 450,000. Improvements to treatment, and even much of our understanding of the pathologies surrounding snakebite have gone little improved in over acentury. This thesis aims to uncovermore of the mysteries surrounding SBE and outline methodologies for the improvement of diagnosticsfor snakebites. Clinicians are crippled by a lack of reliable diagnostical tools and have nothing by whichto treat any of theunderlying conditionsassociated with SBE. Here we aim toanswer two questions,what are these underlying conditionsand are future therapeutics likely to be efficacious; and can toxin-specific antibodies be developed to identify venomcomponentsand diagnose SBE?To answer thefirst,we focus on venom-induced muscle damage and oxidative stress throughcharacterisingcollagenolytic activities of snake venom metalloproteases(SVMP)and methaemoglobinproduction respectively(methaemoglobin is atoxic product ofthe oxidation ofhaemoglobin). This latter effect, was found to bea potentialresult of a wide range of venoms and particularly pronounced in an Elapid, Naja nigricollis, challenging the assumption that this effect is only seenin vipervenoms.In addition to this, the route by which SVMPsinduce permanent skeletal muscle damage was elucidated via the purification of a P-III SVMP and its treatment in skeletalmuscles of mice. Thethreecausativefactors contributingto the prevention of muscleregeneration seen were found to be 1. destruction of collagen and a range of other basement membrane components,2. Damage of blood capillariescausing delayed macrophage infiltrationand blockade of blood supply to the affected regions, and 3. reduced proliferation, migrationand abundance of satellite cells, thereby preventing the muscle regeneration.The use of matrix metalloprotease inhibitors, marimastat and batimastat were found to inhibit a P-I SVMP.The administration of suchtherapeutics requirescareful diagnosis, and thus our second focus wasdeveloping means by which to detect snake venomsin victims. The use of a sequence-structure-functionand phylogeneticapproach in synthesising peptides from which to make toxin-specific antibodies showed some promise butyieldedineffectual antibodies for usein the two-site immunoassaythey weredesigned for. Using antibodiesinstead raised against purified toxins was more successful, allowing the development of relatively specific two-site enzyme-linked immunosorbent assays and lateral flow assays.Together, this study forms a solid basis in order to characterise SBE in more detailand develop diagnostic platforms using novel strategies to not only improve the diagnosis and treatment of snakebitesbut also to better understand the pathophysiology of SBE.

Item Type:Thesis (PhD)
Thesis Supervisor:Vaiyapuri, S. and Bichnell, A.
Thesis/Report Department:School of Chemistry, Food and Pharmacy
Identification Number/DOI:
Divisions:Faculty of Life Sciences > School of Chemistry, Food and Pharmacy
ID Code:88717

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