Norovirus (NoV) is a major cause of infectious human viral gastroenteritis. Detection is important to understanding the epidemiology of NoV and the viral dynamics of NoV infection which is poorly understood. In 2006, a marked increase in gastroenteritis outbreaks occurred worldwide. During this period, a total of 231 stool samples were obtained from patients with acute gastroenteritis from Australia and New Zealand. A total of 186 isolates of NoV were detected and sequenced to determine the genotype and relatedness to known epidemic NoV GII.4 variants. Two GII.4 variants, 2006a and 2006b, were identified in 61.8% and 11.3%, in these cases, respectively. Thus, the increase in NoV gastroenteritis in 2006 was linked to the emergence of two novel co-circulating GII.4 variants, 2006a and 2006b. During an outbreak in an aged-care facility, stool samples were collected from the onset of illness to cessation of viral excretion. Here, viral shedding peaked in the acute stage of illness and continued for an average of 28.7 days. The viral decay rate was 0.76 per day. Prolonged asymptomatic shedding of NoV was detected in the elderly. A quality control for the assessment of molecular based viral assays for NoV and other RNA viruses is necessary to meet current testing requirements. Available controls only monitor the RNA and DNA amplification steps. An MS2 bacteriophage BioBallTM with 100 pfu was evaluated and applied as a multi-purpose phage control. It was assessed as a quality control, in comparison to MS2 phage stock, to validate MS2 phage assays. Furthermore, MS2 BioBallTM was used as a process control for the molecular detection of RNA viruses. It validated every performed step, determined if the assay worked and its sensitivity. Thus, MS2 BioBallTM offered uniformity, stability and reproducibility across molecular based viral detection systems. Overall, this thesis provided valuable insight into the molecular epidemiology of NoV in the southern hemisphere and nature of NoV infections in the elderly. The MS2 BioBallTM provides standardisation and quality control of viral RNA assays. Understanding the genetic diversity and viral dynamics of NoV will be crucial to developing effective intervention and treatment strategies, and ultimately lead to reduced viral gastroenteritis worldwide.
| Identifer | oai:union.ndltd.org:ADTP/232586 |
| Date | January 2008 |
| Creators | Tu, Elise, Biotechnology & Biomolecular Sciences, Faculty of Science, UNSW |
| Publisher | Publisher:University of New South Wales. Biotechnology & Biomolecular Sciences |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://unsworks.unsw.edu.au/copyright, http://unsworks.unsw.edu.au/copyright |
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