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Thesis Format



Master of Science




Menassa, Rima


The University of Western Ontario, Agriculture and Agri-Food Canada

2nd Supervisor

Kohalmi, Susanne E.



Livestock diseases are major hurdles facing the agriculture industry. One major illness affecting the swine industry is the viral porcine reproductive and respiratory syndrome (PRRS). Current methods of controlling its spread are inadequate, so there is urgent need for better prevention tools. Vaccines are the most effective way to control viral diseases because viruses cannot be controlled by antibiotics. Protein nanoparticle-based subunit vaccines provide safe, effective disease prevention. In this study, an epitope derived from portions of the two most abundant PRRS viral surface proteins, M and GP5, was fused to three self‑assembling proteins for use as vaccine candidates. Their expression was examined without the epitope using transient expression in Nicotiana benthamiana, and all three proteins were detected on Western blots. Self-assembling M‑GP5 fusion proteins were also expressed at similar or higher levels than the self‑assembling proteins alone. These findings provide groundwork for future research investigating these PRRS vaccine candidates.

Summary for Lay Audience

One of the major diseases affecting the swine industry around the globe is the porcine reproductive and respiratory syndrome (PRRS). This disease leads to issues with carrying fetal piglets to term in pregnant sows, as well as respiratory and developmental problems in growing piglets. This disease is caused by a virus and cannot be treated by antibiotics. The main method to control the spread of viral diseases is through the use of vaccines, however, those currently available against PRRS are ineffective. Because of this, there is an urgent need for a safer and more effective vaccine against this disease. Therefore, the goal of this research was to produce and examine several vaccine candidates against PRRS. In this project portions of two viral surface proteins, the M-GP5 epitope, were fused to three carrier proteins. Because this was the first time these carrier proteins were expressed in plants, they were first produced on their own to investigate their soluble protein accumulation levels in this expression platform. They were then each fused to the M‑GP5 epitope and their accumulation levels were examined again. All of these proteins had moderate to high soluble accumulation levels, demonstrating their successful expression in plants. This study provides the groundwork for further development of these vaccine candidates so that one day PRRS will no longer be one of the major concerns affecting the global swine industry.

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