Cytokine production in the pathogenesis of avian cholera

Nimal-jayaweera Manelgamage-Don (2011). Cytokine production in the pathogenesis of avian cholera MPhil Thesis, School of Veterinary Science, The University of Queensland.

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Author Nimal-jayaweera Manelgamage-Don
Thesis Title Cytokine production in the pathogenesis of avian cholera
School, Centre or Institute School of Veterinary Science
Institution The University of Queensland
Publication date 2011-09
Thesis type MPhil Thesis
Supervisor Dr. Ian Wilkie
Total pages 123
Total colour pages 11
Total black and white pages 112
Subjects 07 Agricultural and Veterinary Sciences
Abstract/Summary The subject of this thesis is an initial comparison of the responses of selected cytokines in chickens experiencing an acute infection by two strains of Pasteurella multocida. One strain (VP17) was originally isolated from chickens during an outbreak of avian cholera, but has since shown very low virulence when inoculated into healthy adult chickens. The other strain, (VP161) was originally isolated from chickens during an outbreak of avian cholera in Vietnam. This strain has remained highly virulent, and an intramuscular dose of as few as 10 organisms is capable of causing acute avian cholera when injected into healthy adult chickens. IL-1β, IL-6, IL-18, IL-12β, IL-2, IFN-γ, IL-4, IL-10 and TGF-β cytokines, representing the main groups of pro-inflammatory, Th1, Th2 and Th3 were selected on the basis of their known expression in birds, and their apparent correspondence with mammalian cytokines, in order that their expression levels could be compared during high and low virulence infections during the initial 15 hours post infection. The 15 hour limit was chosen because birds experiencing virulent infection usually begin to show signs of severe illness at that time, and are likely to die between 18 and 24 hours post infection. Due to the lack of published information on methods of extracting messenger RNA from chicken leucocytes at the commencement of the study, the first part describes the development and validation of a method for extracting mRNA from chicken leucocytes. Previously published primers were tested for real-time RT-PCR estimation of expression levels of the selected cytokines. The second part of the thesis describes the main experiment, in which the cytokine expression levels of circulating leucocytes during the initial stages of low and high virulence infections are compared. In this study, expressions of all of the cytokines measured were different from those in uninfected controls. There were group differences in the expression of cytokines IL-1β, IL-10 and TGF-β4. While the expression levels for IL-1β and TGF-β4 were significantly higher in VP161 (high virulence) infection, IL-10 expression was significantly higher in VP17 (low virulence) infection. Expression of Th1 cytokines IL-12β and IFN-γ were expressed in sympathy throughout the experiment in both low and high virulence infections. From the results of this experiment it is not possible to determine if the differences in the expression of IL-1β, IL-10 and TGF-β4 are a response to the different rates of proliferation of bacteria, or is a tailored response by the birds to specific properties of the different strains of bacteria.
Keyword Cytokine, pathogenesis, avian cholera
avian cytokines, Pauteurella multocida, cytokine expression
Additional Notes Color pages:60,63,65,73-80

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Created: Fri, 30 Sep 2011, 23:04:55 EST by Mr Nimal-jayaweera Manelgamage-don on behalf of Library - Information Access Service