UBC Theses and Dissertations
The creation of an avian vaccine for West Nile virus Young, Joanne Alison
West Nile Virus (WNV) arrived in North America in 1999 and has since caused significant morbidity and mortality, mainly in birds but also in horses and humans. Many families of birds, especially corvids, are highly susceptible to WNV, with infections often resulting in fatalities. Avian species susceptible to WNV infection also include endangered species, such as the Greater Sage-Grouse (Centrocercus uropbasianuts) and the Eastern Loggerhead Shrike (Lanius ludovicianus migrans). Although WNV is now endemic throughout the continent, to date there is no veterinary vaccine available for birds. This thesis focuses on the use of a recombinant adenovirus to construct vaccines against WNV, that would contain either the envelope or the NS3 ‘genes’ from WNV. To assist in assessing the vaccines, work was undertaken to assess to what extent avian antibody reagents could be used in an avian species for which the antibody was not created. The duck specific CD8 antibody, Du-CD8-1 and the chicken/turkey specific CD4 antibody, CT4, bound to Japanese Quail T cells. The CD4 and CD8 antibody reagents were used to analyse Japanese quail T cell populations, establishing the proportions of CD4+ and CD8+ cells, and discovering a previously unreported population of CD4/CD8 double positive cells. An anti bird IgG antibody was found to bind to chicken, House Sparrow and Japanese Quail IgY; the anti-bird IgG antibody was able to detect IgY from these three species when used as part of a serum ELISA assay. Results from initial vaccine testing in Japanese Quail (Coturnix japonica), indicated that the vaccines activated more T cells and triggered production of higher levels of antibodies in vaccinated birds compared to unvaccinated controls. This was achieved using an intracellular interferon gamma (IFN-γ) assay to assess T cell activation and a serum ELISA to measure levels of WNV specific antibodies. During a challenge assay, using a wild population of House sparrows (Passer domesticus) following infection with WNV, vaccinated birds showed overall reduced levels of viremia compared to unvaccinated controls.
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