Mycoplasma gallisepticum (MG) is an economically important pathogen of poultry worldwide, causing chronic respiratory disease in both chickens and turkeys. Little research has been done to characterize the MG field strains present in southern Africa. Field evidence however, suggested breaks in the vaccinations against MG, despite the proper cold chain and correct administration. Molecular methods were used to screen various poultry farms in South Africa and Zimbabwe for MG. Isolates were further characterized by gene-targeted sequencing (GTS). Portions of the cytadhesin pvpA, gapA, mgc2 genes and the uncharacterized surface lipoprotein gene designated MGA_0319 were sequenced and analysed.
Three MG strains were identified in this study: a Ts-11-like strain; a strain showing closest percentage identity to the atypical MG RV-2 strain found in Israel, however with the lack of a large deletion within the pvpA region; and lastly an isolate from Zimbabwe, likely to be a novel MG strain. The latter contained a unique, large, in-frame nucleotide insertion in the mgc2 gene. Antigenically-significant variation (determined in silico) within the membrane surface proteins of this isolate was found compared to the MG Rlow strain used as an inactive vaccine on the poultry farm. It is thus postulated that by MG altering its antigenic profile, it allows effective avoidance of immune recognition and antibodies produced as a result of vaccination with inactivated and possibly live MG vaccines. Further research is however needed to substantiate this claim.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-05172013-104022 |
| Date | 17 May 2013 |
| Creators | Moretti, Serena Angela |
| Contributors | Ms CE Boucher, Prof RR Bragg |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-05172013-104022/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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