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Title: Novel strategies for the characterisation and diagnosis of snakebite envenomation
Author: Williams, Harry Fonseca
ISNI:       0000 0004 8508 3481
Awarding Body: University of Reading
Current Institution: University of Reading
Date of Award: 2019
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Globally, snakebite envenoming (SBE) kills in excess of 100,000 people annually and causes sequalae to over 450,000. Improvements to treatment, and even much of our understanding of the pathologies surrounding snakebite have little improved in over a century. This thesis aims to uncover more of the mysteries surrounding SBE and outline methodologies for the improvement of diagnostics for snakebites. Clinicians are crippled by a lack of reliable diagnostical tools and have nothing by which to treat any of the underlying conditions associated with SBE. Here we aim to answer two questions, what are these underlying conditions and are future therapeutics likely to be efficacious; and can toxin-specific antibodies be developed to identify venom components and diagnose SBE? To answer the first, we focus on venom-induced muscle damage and oxidative stress through characterising collagenolytic activities of snake venom metalloproteases (SVMP) and methaemoglobin production respectively (methaemoglobin is a toxic product of the oxidation of haemoglobin). This latter effect, was found to be a potential result of a wide range of venoms and particularly pronounced in an Elapid, Naja nigricollis, challenging the assumption that this effect is only seen in viper venoms. In addition to this, the route by which SVMPs induce permanent skeletal muscle damage was elucidated via the purification of a P-III SVMP and its treatment in skeletal muscles of mice. The three causative factors contributing to the prevention of muscle regeneration seen were found to be: 1. destruction of collagen and a range of other basement membrane components; 2. Damage of blood capillaries causing delayed macrophage infiltration and blockade of blood supply to the affected regions; and 3. reduced proliferation, migration and 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 such therapeutics requires careful diagnosis, and thus our second focus was developing means by which to detect snake venoms in victims. The use of a sequence-structure-function and phylogenetic approach in synthesising peptides from which to make toxin-specific antibodies showed some promise but yielded ineffectual antibodies for use in the two-site immunoassay they were designed for. Using antibodies instead 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 detail and develop diagnostic platforms using novel strategies to not only improve the diagnosis and treatment of snakebites but also to better understand the pathophysiology of SBE.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral