Browsing by Author "Olivier, Adriaan Jacobus"

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    DNA vaccines against mycoplasma elicit humoral immune responses in ostriches
    (Frontiers Media, 2019-05-14) Wium, Martha; Jonker, Hester Isabella; Olivier, Adriaan Jacobus; Bellstedt, Dirk Uwe; Botes, Annelise; Leite, Luciana
    In ostriches, the population densities resulting from intensive rearing increases susceptibility to pathogens such as mycoplasmas. In addition to good management practices, vaccination offers an attractive alternative for controlling mycoplasma infections in food animals, instead of using antibiotics, which often leave unacceptable residues. The use of live attenuated vaccines, however, carry the concern of reversion to virulence or genetic recombination with field strains. Currently there are no commercially available vaccines against ostrich-infecting mycoplasmas and this study therefore set out to develop and evaluate the use of a DNA vaccine against mycoplasma infections in ostriches using an OppA protein as antigen. To this end, the oppA gene of “Mycoplasma nasistruthionis sp. nov.” str. Ms03 was cloned into two DNA vaccine expression vectors after codon correction by site-directed mutagenesis. Three-months-old ostriches were then vaccinated intramuscularly at different doses followed by a booster vaccination after 6 weeks. The ability of the DNA vaccines to elicit an anti-OppA antibody response was evaluated by ELISA using the recombinant OppA protein of Ms03 as coating antigen. A statistically significant anti-OppA antibody response could be detected after administration of a booster vaccination indicating that the OppA protein was successfully immunogenic. The responses were also both dose and vector dependent. In conclusion, the DNA vaccines were able to elicit an immune response in ostriches and can therefore be viewed as an option for the development of vaccines against mycoplasma infections.
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    Ecology and habitat suitability of Cape mountain zebra (Equus zebra zebra) in the Western Cape, South Africa
    (Stellenbosch : Stellenbosch University, 2019-12) Olivier, Adriaan Jacobus; Leslie, Alison J.; Ranson, Jason I.; Stellenbosch University. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology.
    ENGLISH ABSTRACT: Endemic to South Africa, the Cape mountain zebra (Equus zebra zebra) historically occurred throughout the Western Cape, and parts of the Northern and Eastern Cape. However, due to human impacts fewer than 50 individuals remained by the 1950’s. Conservation efforts over the past 50 years have resulted in the population increasing to over 4700 individuals and having moved on the IUCN red list, from Critically Endangered to Least Concern. As there are still many isolated meta-populations, CapeNature established a Biodiversity Management Plan for the conservation of Cape mountain zebra in the Western Cape. In 2001, 15 (six males and nine females) Cape mountain zebra was reintroduced into Bakkrans Nature Reserve, situated in the Cederberg Wilderness Area of South Africa. More than 17 years after the initial reintroduction, the species have persisted in this arid environment. No long-term monitoring has been carried out on this population of Cape mountain zebra. In this study, the demographics, diet, artificial waterhole dependency and habitat suitability of Cape mountain zebra was investigated. Individual stripe pattern was used to determine Cape mountain zebra demographics. Driving transects and camera traps identified 21 unique individuals (100% of population) of which 19 were adults (90.4%) one was a yearling (4.8%) and one was a foal (4.8%). It was expected that the population would experience an initial lag in population growth where after it would rapidly increase; however, population growth is still very low. Adult Cape mountain zebra on the reserve currently exhibit an extremely male biased sex ratio of 1:0.27 (male:female). Population structure and organization does not display similarities to those of other well-established populations; however, a male biased population structure has been associated with other populations in the Western Cape. In addition, microhistology was used to determine the seasonal dietary preference of Cape mountain zebra. Results showed that Cape mountain zebra in Bakkrans Nature Reserve are mixed feeders as grass contributed to 41.5% of the annual diet, restios 16.4% and dicotyledons 29.3%. Leaf material was preferred annually, while stem, flower and inflorescence use increased during the wet season. Green grasses were preferred annually and were accepted >60% across all seasons. Tallest swards were accepted during the late dry season and shortest in the late wet season. Camera traps were used to study artificial waterhole dependency of Cape mountain zebra. Artificial watering points in the low lying areas were utilized more frequently due to more suitable habitat and higher zebra densities. Waterhole use was highest around dusk peaking at 19:00h and 20:00h. As seasons changed, Cape mountain zebra shifted their preference times to avoid intraspecific competition and accommodate for the earlier and later shifting of dusk. Finally, habitat suitability in Bakkrans Nature Reserve was analysed to determine how suitable the habitat is for a reintroduced population of Cape mountain zebra. Additionally, the suitability of three other reserves, Grootwinterhoek, Limietberg and Matjiesrivier Nature Reserves was tested for the potential reintroduction of Cape mountain zebra. Results confirmed that Bakkrans Nature Reserve has poor habitat suitability for Cape Mountain Zebra as scores were <10 and similar results were found for Matjiesrivier Nature Reserve. Furthermore, the Grootwinterhoek Nature Reserve is also of poor habitat for Cape mountain zebra. Of all the reserves, Limietberg Nature Reserve had the most suitable habitat. Results from this study, have identified issues facing Cape mountain zebra conservation in Bakkrans Nature Reserve as well as the Western Cape and management recommendations were presented.