West Nile Virus (WNV) has emerged as a major cause of viral encephalitis. Since its outbreak in the United States 27,000 people have presented with clinical WNV disease resulting in 1074 fatalities. WNV causes a range of disease from mild febrile illnesses to severe and fatal encephalitis. To date, there are currently no therapeutic agents or vaccines available to treat WNV infection in humans. In order to address this, a better understanding of the mechanisms responsible for viral neuroinvasion and neuropathology are required. Using a range of in vitro and in vivo studies, we have investigated the routes by which WNV enters the CNS. Virus replication was observed in the brain microvascular endothelial cells in mice that succumbed to WNV encephalitis. Moreover, we demonstrated that infection of a polarized HBMEC with WNV induced apoptosis. Microarray analysis of WNV-infected HBMEC’s revealed that WNV elicited the expression of cytokines that have been shown to contribute to permeablization of the BBB. These findings suggest that WNV can enter the CNS through the BBB via multiple mechanisms. Real-time RT-PCR performed on WNVinfected HBMECs identified two host genes involved in the host cellular anti-oxidant response that were differentially regulated during viral infection. Furthermore, the addition of the antioxidant, N-acetylcysteine, restored cell viability and decreased viral replication, indicating that oxidative stress contributes to WNV-induced pathogenesis. The current state of knowledge regarding the pathogenesis of WNV encephalitis is based on studies that have defined the role of systemic immune responses to WNV. Limited investigations have been undertaken to determine the contribution of brain cells in the defence, or damage to the brain once WNV has gained access to the CNS. Real-time RT-PCR results in conjunction with in vivo CBA assay data, suggested several candidate host genes that could contribute to the pathogenesis of WNV. Thus, it is necessary to further define the mechanisms of WNV induced pathogenesis as this will aid in the development of targeted strategies to prevent neurological infection and mitigate neurological diseases in affected individuals.

Thesis (M.S.), Biology--University of Central Oklahoma, 2007. / Includes bibliographical references (leaves 27-35 ).

Thesis (Ph.D.)--York University, 2006. Graduate Programme in Mathematics and Statistics. / Typescript. Includes bibliographical references (leaves 126-132). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR19847

Thesis (Ph. D.)--Georgia State University, 2007. / Title from file title page. Margo Brinton, committee chair; W. David Wilson, Teryl Frey, committee members. Electronic text (120 p. : ill. (some col.)) : digital, PDF file. Description based on contents viewed Nov. 20, 2008. Includes bibliographical references.

Thesis (M.A.)--State University of New York at Binghamton, Dept. of Geography, 2006. / Includes bibliographical references.

Thesis (Ph.D.)--University of Delaware, 2008. / Principal faculty advisors: Jack B. Gingrich and Douglas W. Tallamy, Dept. of Entomology & Wildlife Ecology. Includes bibliographical references.

Thesis (Ph. D.)--University of Oklahoma. / Bibliography: leaves 139-166.

West Nile virus (WNv) is an arbovirus and is transmitted by infected mosquitoes after feeding on the blood of birds carrying the virus. The Canadian WNv national surveillance system has just completed its tenth year of operation. The thesis is to evaluate the surveillance system and analyze multi-year human data. The evaluation includes the use of multiple lines of complementary methods such as the US CDC surveillance guidelines, Canadian Evaluation Framework, document review and a survey. Logistic and Poisson regressions were used for data analyses. WNv has become endemic in most parts of Canada since the virus occurred in 2001. The virus activity is peak around August. High numbers of human cases with WNv neurological syndrome identified pose a significant health concern due to the long term sequelae among affected patients. WNv national surveillance met its main objectives and there is a continual need for the surveillance.

West Nile virus (WNV) belongs to the Flaviviridae family, a virus family of which many members are known as human pathogens. WNV has a worldwide distribution and strains that cluster in lineage II is endemic to sub-Saharan Africa. The complete nucleotide sequence of four lineage II West Nile virus strains, isolated in South Africa from patients with mild or severe WNV infections, were determined. Using a murine model, these strains had been shown to produce either highly or less neuroinvasive infections and induced similar genes to corresponding highly or less neuroinvasive lineage I strains. Nucleotide and amino acid sequence comparison between highly and less pathogenic lineage II strains demonstrated that the non-structural genes and in particular the gene coding for the NS5 proteins were the most variable. All the lineage II strains sequenced in this study were found to possess the E-protein glycosylation site previously postulated to be associated with virulence. Comparison of the signalase cleavage sites suggested that lineage II strains may be cleaved slightly more efficiently than lineage I strains in the C-prM junction, but less efficiently between prM and E genes. Relative to the highly neuroinvasive strains sequenced in this study major deletions were found in the 3’ noncoding region of 2 lineage II strains shown in previous studies to be either less- or not at all neuroinvasive. This is the first report of full genome sequences of highly neuroinvasive lineage II WNV strains. Currently available commercial WNV ELISA kits were developed with lineage I WNV strains and are expensive to use. For these reasons the development of a potential ELISA diagnostic assay based on the South African lineage II strain, H442, was envisaged. Such assay, if reliable and efficacious would be a useful tool towards WNV surveillance. The prM and E genes were selected to be expressed as recombinant antigens because of their co-expression nature and because the envelope protein is the principal target for neutralization. After cloning of the respective genes and verification of integrity, a mammalian expression system was utilized. Different mammalian cells and transfection media were tested and BHK 21 cells with SuperFect transfection medium were found to be best. Attempted expression of proteins was tested with immunofluorescent antibody testing as well as SDS-PAGE and Western blot analysis. Expression of recombinant WNV antigens were also tested in indirect and sandwich ELISA’s systems. It was however not possible to perform these two ELISA systems at a satisfactory level or clearly indicated if expression of proteins was successful. / Dissertation (MSc (Microbiology))--University of Pretoria, 2008. / Microbiology and Plant Pathology / unrestricted

Objectives. Acute flaccid paralysis (AFP) has recently emerged as a major central nervous system complication associated with West Nile virus (WNV) infection. The spectrum of clinical presentations of AFP in WNV infection and its sequelae have not been well-studied. Methods. We describe three patients with AFP due to WNV infection and review the clinical presentations of 56 patients with this complication derived from published studies. Results. Patients with AFP and WNV presented with a spectrum of illness ranging from single extremity paralysis to quadriparalysis with cranial nerve involvement. Patients commonly developed respiratory failure (54%) and bladder dysfunction (22%). While fever was nearly universal (92%), signs of meningismus were less common (17%). Cerebrospinal fluid (CSF) analysis generally revealed a modest pleocytosis, and imaging studies were not diagnositic. Persistent neurologic impairment occurred in all survivors; overall mortality rate was high (22%) and was associated with both the extent of paralysis and advanced age. Conclusion. AFP in the setting of WNV is associated with significant mortality and long-term morbidity.