Browsing by Author "Pretorius, Benita"
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- ItemThe ostrich mycoplasma Ms01 : the identification, isolation, and modification of the P100 vaccine candidate gene and immunity elicited by poultry mycoplasma vaccines(Stellenbosch : Stellenbosch University, 2009-03) Pretorius, Benita; Bellstedt, D. U.; Botes, Annelise; Stellenbosch University. Faculty of Science. Dept. of Biochemistry.ENGLISH ABSTRACT: The South African ostrich industry is currently being threatened by respiratory disease in feedlot ostriches with dramatic production losses. Three ostrich-specific mycoplasmas, Ms01, Ms02 and Ms03 were identified to be associated with respiratory disease in ostriches in South Africa. There is currently no registered mycoplasma vaccine available for use in ostriches. In order to prevent mycoplasma infections in South African ostriches, the ostrich industry has launched an investigation into possible strategies for vaccine development. This thesis describes different strategies for the establishment of immunity in ostriches against the ostrich-specific mycoplasmas. Firstly, the effectiveness of existing poultry mycoplasma vaccines to provide protection in ostriches against ostrich mycoplasma infections was tested. To this end, ostriches received primary and secondary vaccinations with poultry mycoplasma vaccines against Mycoplasma synoviae or Mycoplasma gallicepticum, respectively, after which protection against ostrich-specific mycoplasma was evaluated. Even though the specific identity of the ostrich-specific mycoplasmas (Ms01, Ms02, and/or Ms03) responsible for subsequent infection of immunized ostriches was not determined, it was concluded that poultry mycoplasma vaccines do not provide protection against these mycoplasma infections in ostriches. This appears to be the result of low levels of antibody crossreactivity between mycoplasmas, highlighting the necessity for the development of specific vaccines against each of the individual ostrich-specific mycoplasmas. Secondly, the development of a DNA vaccine against Ms01 was investigated. With the aim of developing an Ms01-specific DNA vaccine, the entire Ms01 genome was sequenced using GS20 sequencing technology. Bioinformatic searches were launched for the identification of an appropriate vaccine candidate gene in the Ms01 genome. The P100 gene, showing a high degree of homology with the P100 gene of the human pathogen M. hominis, was subsequently identified. After successful cloning, and modification of ten specific codons within the gene to correct for alternative codon usage, the modified P100 gene of Ms01 is now ready for insertion into a suitable DNA vaccine vector, for subsequent use as a DNA vaccine in ostriches.