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The development of polyester bead-based particulate subunit vaccine against Johne's disease : a thesis presented in partial fulfillment of the requirements of the degree of Master of Science in Microbiology, Massey University, Palmerston North, Institute of Fundamental Science
Johne’s disease is the intestinal infection in ruminants caused by Mycobacterium avium
subspecies paratuberculosis (MAP). The disease is economically important in the dairy
industry as infection of the calves or mature cattle can result in death. Current
vaccination as a part of disease control is not only partially protective against MAP but
also interferes with current diagnostic test for bovine tuberculosis. Therefore, more
effective and defined vaccines are needed. In this study, vaccine candidates were
developed by bioengineering Escherichia coli to produce polyhydroxyalkanoate (PHA)
beads displaying selected vaccine candidate antigens as fusion proteins. The selected
antigens were the MAP 85 antigen complex (Ag85A and Ag85B), Superoxide
dismutase (SOD) and a recombinant fusion protein 74F, however, only the antigenpresenting
beads with truncated Ag85A, Ag85B and SOD were successfully produced
and purified. The fusion protein comprising the respective antigens was identified and
confirmed to be associated with PHA beads. The PHA beads were partially purified for
future characterisations such as binding of antigen specific antibodies on PHA beads in
vitro and immunological properties in animal models