Browsing by Author "Brandt, Sonja"

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    Preliminary investigations into the use of DNA vaccines to elicit protective immune responses against the ostrich mycoplasma Ms01
    (Stellenbosch : Stellenbosch University, 2012-03) Brandt, Sonja; Bellstedt, D. U.; Botes, Annelise; Stellenbosch University. Faculty of Science. Dept. of Biochemistry.
    ENGLISH ABSTRACT: Mycoplasmas are evolutionarily advanced prokaryotes which have acquired the elite status of “next generation” bacterial pathogens and necessitate new paradigms in completely understanding their disease potential. The recurrent failure to eradicate mycoplasmal diseases from humans and animals through the use of antibiotics and other techniques have led to the conclusion that the most promising approach would be the development of an effective vaccine with which to control mycoplasma infections. The identification of three species of Mycoplasma which infect South African ostriches, causing huge losses to the South African ostrich industry each year, has thus prompted a search for new vaccination strategies with which to control and eradicate them. This study investigated the use of three potential DNA vaccines, utilizing the adherence-associated Ms01 OppA protein as antigenic determinant to generate antibody responses against the ostrich-infecting Ms01 organism. A vaccine trial in which the antigenic potential of the pCIneo, VR1012 and VR1020 DNA vaccines were evaluated in ostriches, necessitated the development of an enzyme-linked immunosorbent assay (ELISA) for serological analysis. To this end, the Ms01 oppA gene was isolated, cloned into a prokaryotic expression vector and expressed as a recombinant GST-fusion product in Escherichia coli. The successful expression and purification of the recombinant protein enabled its subsequent utilization as antigen in the generation of an ELISA. The ELISA displayed a high signal to background ratio. Using this ELISA, it could be shown that ostriches already possessed antibodies to the Ms01 organism prior to vaccination, a probable result of previous exposure. The expected antibody response pattern could not be detected in ostriches in response to the vaccinations, and therefore no final conclusion as to the immunostimulatory capabilities of the DNA vaccines could be drawn. Further vaccination trials in which ostriches that do not possess immunity to ostrich mycoplasmas, are required in order to obtain conclusive results.