DEVELOPMENT OF ANTIVIRAL AGENTS FOR THE TREATMENT OF HENDRA AND NIPAH VIRUS INFECTIONS.

Mohamad Aljofan (2010). DEVELOPMENT OF ANTIVIRAL AGENTS FOR THE TREATMENT OF HENDRA AND NIPAH VIRUS INFECTIONS. PhD Thesis, Veterinary Science and Animal Production, The University of Queensland.

       
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Author Mohamad Aljofan
Thesis Title DEVELOPMENT OF ANTIVIRAL AGENTS FOR THE TREATMENT OF HENDRA AND NIPAH VIRUS INFECTIONS.
School, Centre or Institute Veterinary Science and Animal Production
Institution The University of Queensland
Publication date 2010-05
Thesis type PhD Thesis
Supervisor As/Prof Joanne Meers
Dr Bruce Mungall
Dr Wojtek Michalski
Total pages 340
Total colour pages 41
Total black and white pages 299
Subjects 07 Agricultural and Veterinary Sciences
Abstract/Summary Hendra virus (HeV) and Nipah virus (NiV) are emerging pathogens that resulted in previously unrecognised fatal diseases in humans and animals. They belong to a newly formed genus, Henipavirus, in the Paramyxovirdae family; a diverse group of large, enveloped, negative sense RNA viruses that include a number of important human and animal pathogens. HeV first emerged in Australia in 1994, where it fatally infected a horse trainer and a large number of horses with fatal consequences. The initial NiV outbreak occurred in peninsular Malaysia 1998, where it induced severe morbidity and mortality in animals and humans that resulted in the death of more than 100 humans and the culling of more than 1 million pigs. Both HeV and NiV have continued to reemerge causing major disease outbreaks in Australia and Asia, respectively. To date, there is no therapeutic available to either treat or prevent these lethal viral infections, necessitating their classification as biological safety level 4 (BSL4) pathogens and their inclusion as NIAID category C priority pathogens. The high risk of further outbreaks and wider spread of the diseases introduced a high demand for therapeutic entities against the highly pathogenic infections induced by HeV and NiV. The aim of this PhD project was to develop appropriate drug screening methodology to enable the identification of potential antiviral agents for the treatment of henipavirus infections. The main hypothesis of this thesis was that the screening of a large number of compounds against live henipaviruses would result in the identification of potential antiviral agents for the treatment of these deadly infections. To initiate the study, a cell monolayer based assay for rapid quantitation of HeV and NiV infection was developed. Rather than implementing antiviral screening methods using surrogate technologies, a novel high throughput screening (HTS) methodology was developed and deployed to assess the antiviral potential of novel compounds directly against live viruses in a BSL4 laboratory. The newly developed method is the first HTS method reported for use in a BSL4 environment. The results indicated that this approach can significantly reduce lead development time and can also reduce the possibility of false positives. The suitability and sensitivity of the proposed method was further validated and compared using different cell lines. The HTS methodology was used in single blind design to evaluate the antiviral competency of more than 8,000 novel compounds against live HeV and NiV viruses. This screening campaign resulted in the identification of a number of potential antiviral hits capable of inhibiting viral replication in vitro. Almost 300 novel compounds showed more than 50% inhibition of viral replication, 28 compounds showed more than 90% inhibition, of which nine compounds exhibited less than 10% crude cellular toxicity. Some of the 28 novel compounds that displayed more than 90% inhibition of viral replication are commercially available and were described as potential anti- henipavirus antiviral drugs for non systemic usage. Three of the nine hit compounds were selected to participate in the lead optimisation stage, which represents an early key phase of the drug development process. As an alternative strategy for drug development, the newly developed HTS methodology was used to screen several existing therapeutic drugs against live henipaviruses. The selection of the existing therapeutics was based on an earlier determination that disruption of intracellular calcium release resulted in potent antiviral efficacy during the novel drug screening campaign. The screening of the existing therapeutic compounds resulted in the identification of several potential antiviral agents against henipaviruses. These compounds have defined mechanism of actions for which they are licensed for; however, their specific antiviral mechanisms against HeV and NiV are still unknown. The successful establishment of the first HTS drug screening methodology suitable for BSL4 laboratory usage presents a feasible and rapid strategy for identification of potential drugs for the treatment of henipaviruses and possibly other BSL4 pathogens. This thesis presents for the first time, novel potential antiviral compounds as well as existing off-licence therapeutics capable of treating these deadly infections. It also describes a prospective anti-henipavirus antiviral target that may permit the discovery of antiviral drugs that could significantly contribute to the management of these lethal zoonotic pathogens.
Keyword Henipaviruses, hendra virus, nipah virus, antivirals, high throughput screening, BSL4, brilliant green, gentian violet, gliotoxin and ion channel modulators.
Additional Notes Colour pages (page number of 340): 25, 36, 40-42, 54, 64, 65, 99, 100, 102, 105, 109, 126, 134, 135, 161, 162, 173, 180, 188, 235, 237-239, 241-255. Landscape pages (page number of 340): 75, 78, 79, 86, 99, 100, 101, 126, 129, 133-135, 156-159, 162, 163, 167, 180, 189, 190.

 
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Created: Fri, 01 Oct 2010, 10:12:26 EST by Mr Mohamad Aljofan on behalf of Library - Information Access Service