Project topics and materials
Get Complete Project Material File(s) Now! »
INTRODUCTION
The Cape mountain zebra (Equus zebra zebra, Linnaeus 1758) is regarded as one of the most endangered large mammals in South Africa (Novellie et al. 2002) and the estimated extant 600 individuals (Glenn 2006) are protected in small numbers in reserves of which most are situated in their natural habitat. In two of the smallest of these reserves, Bontebok National Park (3 486 ha) and Gariep Dam Nature Reserve (6 000 ha) respectively, the presence and incidence of sarcoids were reported in 1995 and 1998 (Lange 2004; Nel et al. 2006). These were the first records of this most common tumour of horses and donkeys in free roaming zebras.
The Bontebok National Park is situated in the winter rainfall area, next to the Langeberg near Swellendam, Western Cape on the banks of the Breede River and Gariep Nature Reserve is situated in the arid southern Free State bordering the Gariep Dam (Figure 1). The suitability of the two parks for Cape mountain zebras is questionable since a habitat analysis of the Bontebok National Park in the Western Cape Province (Figure 1) showed that the general habitat is marginal for the maintenance of Cape mountain zebras (Kraaij & Watson 2009) and the Gariep Dam Nature Reserve, situated in the southern part of the Free State Province along the northern shore of the Gariep Dam, is sparsely covered with vegetation classified as eastern mixed Nama-Karoo (Low & Rebelo 1996). This is the most northern area in South Africa where Cape mountain zebras occur, their natural habitat being more to the south, and more closely confined to mountainous areas that offer the required types of grazing and shelter in the form of kloofs and ridges (Smithers 1983). In both of these parks the grazing is shared with other herbivore species. The Bontebok National Park was proclaimed in 1931 to prevent the last few remaining bonteboks (Damaliscus dorcas) from becoming extinct. The rare red hartebeests (Alcelaphus buselaphus) also occur here.
The ecological management plan of the Gariep Nature Reserve (proclaimed in 1985) recommends that the numbers of zebras are kept between 50 and 70 for this reserve (Nel et al. 2006). Other game species such as springboks (Antidorcas marsupialis), klipspringers (Oreotragus oreotragus), elands (Taurotragus oryx), kudus (Tragelapus strepsiceros), gemsboks (Oryx gazella), swart wildebeests (Connochaetus gnou), and rooi hartebeests (Alcelaphus buselaphus) also share the available grazing in the park. Cape mountain zebra numbers dwindled to those in a few isolated populations, and all the existing Cape mountain zebras are descendants of a nucleus of 11 individuals (Bigalke 1952). They were and still are protected in the Mountain Zebra National Park in Cradock in the Eastern Cape Province, South Africa, from where they were reintroduced into yet other reserves. The zebras within these reserves also form closed herds and have become highly inbred.
Zebras are resistant to equine viral diseases such as African horsesickness virus, equine herpesvirus, equine encephalosis virus, equine arteritis virus, and although antibodies against several viral diseases have been demonstrated, clinical diseases were not seen (Barnard 1993; 1994; Blunden et al. 1998; Borchers et al. 2005). Zebras can be a source of African horsesickness virus, as the virus over winter in the zebra while they show no clinical signs of the disease (Erasmus 2008). Recently a high incidence of sarcoid lesions appeared in two parks, Bontebok National Park (Figure 2) and Gariep Dam Nature Reserve (Figure 3) affecting 53% and 24% of the Cape mountain zebra populations respectively (Lange 2004; Nel et al. 2006). Characterization of the cause of these sarcoid forms the main emphasis of this study. Bovine papillomaviruses types 1 and 2 (BPV-1 and BPV-2) are associated with sarcoids, the most common dermatological skin lesion in equidae (Goodrich et al.1998) and have been detected in donkeys (Reid et al. 1994), mules (Jackson 1936), horses (Otten et al. 1993), and two cases were reported from captive zebra in the United States of America (Löhr et al. 2005). Papillomaviruses are oncogenic viruses which infect epithelial cells causing hyperproliferative lesions. They infect cutaneous or mucous epithelia in a variety of hosts. Bovine papillomaviruses 1 and 2, were found not to be as species-specific as other papillomaviruses which only infect their natural hosts.
Sarcoids in horses have been associated with major histocompatibility complex class II, with serological determinants to the DR and DQ loci, although the precise cause has never been determined (Lazary et al. 1988; Marti et al. 1996). The zebras in the reserves, being inbred, might have become inbred for the MHC region with increased prevalence of a haplotype conferring increased risk for sarcoids tumours. Other free-roaming game species, with wart-like skin lesions, such as giraffes (Giraffa camelopardalis), have also been observed in the Kruger National Park, which is situated on the eastern border of South Africa bordering Mozambique, the wart-like skin lesions, often impairing their well-being and making them unsightly. A sable antelope (Hippotragus niger), kept on a game farm in the Kimberley district, Northern Cape Province, South Africa, developed a similar lesion on one of its legs. This arid area of South Africa is not the natural habitat of these antelopes as they are a savanna woodland species (Smithers 1983). Electron microscopically, virus particles have also been demonstrated in skin papillomas in an impala (Aepyceros melampus) and a giraffe in Kenya (Karstad & Kaminjolo 1978).
TABLE OF CONTENTS :
- ACKNOWLEDGEMENTS
- SUMMARY
- TABLE OF CONTENTS
- FIGURES
- TABLES
- CHAPTER ONE: INTRODUCTION AND LITERATURE REVIEW
- 1.1 INTRODUCTION
- 1.2 LITERATURE REVIEW
- 1.2.1 Southern African zebras
- 1.2.1.1 The genus Equus
- 1.2.1.2 Distribution
- 1.2.1.3 Phenotype
- 1.2.1.4 Status
- 1.2.1.5 Conditions affecting zebras
- 1.2.2 Sarcoid
- 1.2.2.1 Clinical appearance
- 1.2.2.2 Treatment
- 1.2.2.3 Viral aetiology
- 1.2.2.4 Disease transmission
- 1.2.2.5 Virus latency
- 1.2.2.6 Immune suppression
- 1.2.2.7 Co-factors for carcinogenesis
- 1.2.2.8 Genetic factors
- 1.2.3 Papillomaviruses
- 1.2.3.1 Phylogeny of papillomavirus
- 1.2.3.2 Taxonomy of papillomavirus
- 1.2.3.3 The virion
- 1.2.3.4 The viral genome
- 1.2.3.5 Oncoproteins
- 1.2.3.6 Sequence variation
- 1.2.3.7 Viral replication
- 1.2.3.8 Malignancy
- 1.2.3.9 Papillomavirus infection in other species
- 1.2.4 Diagnostic methods applicable to the study
- 1.2.4.1 Histopathological diagnosis
- 1.2.4.2 Molecular techniques
- 1.3 REFERENCES
- CHAPTER TWO: DETECTION OF BOVINE PAPILLOMAVIRUS DNA IN SARCOID-AFFECTED AND HEALTHY FREE-ROAMING ZEBRA (EQUUS ZEBRA) POPULATIONS IN SOUTH AFRICA
- ABSTRACT
- 2.1 INTRODUCTION
- 2.2 MATERIALS AND METHODS
- 2.2.1 Study population and sample collection
- 2.2.2 Histopathology
- 2.2.3 DNA extraction
- 2.2.4 Conventional PCR amplification of a region of the E5 open reading frame
- 2.2.5 Real-time PCR
- 2.2.5.1 Primer and hybridization probe design
- 2.2.5.2 Real-time PCR conditions
- 2.2.5.3 Quantitative sensitivity
- 2.2.6 Molecular cloning and sequencing
- 2.3 RESULTS
- 2.3.1 Conventional PCR amplification of a region of the E5 ORF
- 2.3.2 BstX1 restriction digestion of the PCR amplified E5 ORF
- 2.3.3 Real-time PCR
- 2.3.3.1 Specificity of the real-time PCR assay
- 2.3.3.2 Sensitivity of the real-time PCR assay
- 2.3.3.3 Detection of BPV DNA in clinical samples
- 2.3.4 Molecular cloning and sequencing
- 2.4 DISCUSSION
- 2.5 REFERENCES
- CHAPTER THREE: PHYLOGENY OF PAPILLOMAVIRUSES OBTAINED IN SKIN LESIONS OF CAPE MOUNTAIN ZEBRA (EQUUS ZEBRA ZEBRA, LINNAEUS, 1758)
- ABSTRACT
- 3.1 INTRODUCTION
- 3.2 MATERIALS AND METHODS
- 3.2.1 Study population and sample collection
- 3.2.2 DNA extraction
- 3.2.3 Conventional PCR amplification of a region of the E5 open reading frame
- 3.2.3.1 Real-time PCR
- 3.2.3.2 Molecular cloning and sequencing
- 3.2.3.3 Phylogenetic analysis
- 3.3 RESULTS
- 3.3.1 Real-time PCR
- 3.3.2 Sequencing results
- 3.3.3 Phylogenetic reconstruction
- 3.4 DISCUSSION
- 3.5 REFERENCES
- CHAPTER FOUR: DEVELOPMENT OF A TYPING SYSTEM TO DETERMINE MHC HAPLOTYPES IN THE ZEBRA
- ABSTRACT
- 4.1 INTRODUCTION
- 4.2 MATERIALS AND METHODS
- 4.2.1 Zebras and horse DNA samples for comparison
- 4.2.2 Conventional PCR amplification of a second exon class II
- 4.2.3 Cloning and sequencing
- 4.2.4 MHC Typing: Single strand conformational polymorphism analysis
- 4.3 RESULTS
- 4.3.1 Sequencing
- 4.3.1.1 Class I
- 4.3.1.2 Class II
- 4.3.2 Single strand conformational polymorphism
- 4.3.2.1 DRB
- 4.3.2.2 DQB
- 4.4 DISCUSSION
- 4.5 REFERENCES
- CHAPTER FIVE: MHC CLASS II VARIATION AMONG ZEBRAS WITH SARCOID TUMOURS
- ABSTRACT
- 5.1 INTRODUCTION
- 5.2 MATERIALS AND METHODS
- 5.2.1 Study population and sample collection
- 5.2.2 DNA extraction
- 5.2.3 Conventional PCR amplification of the second exon class II
- 5.2.4 Molecular cloning and sequencing
- 5.2.5 MHC Typing: Single-Strand Conformational Polymorphism Analysis
- 5.3 RESULTS
- 5.3.1 Amplification of MHC DNA fragments
- 5.3.2 Comparison of SSCP DRB and DQB profiles for zebras with and without sarcoid tumours
- 5.3.2.1 DRB
- 5.3.2.2 DQB
- 5.3.3 Sequencing
- 5.4 DISCUSSION
- 5.5 REFERENCES
- CHAPTER SIX: DETECTION AND CHARACTERIZATION OF PAPILLOMAVIRUS SKIN LESIONS OF GIRAFFE (GIRAFFA CAMELOPARDALIS, LINNAEUS, 1758) AND SABLE ANTELOPE (HIPPOTRAGUS NIGER, HARRIS, 1838) IN SOUTH AFRICA
- ABSTRACT
- 6.1 INTRODUCTION
- 6.2 MATERIALS AND METHODS
- 6.2.1 Sample collection
- 6.2.2 Electron microscopy
- 6.2.3 Histopathology
- 6.2.4 DNA extraction
- 6.2.5 Real-time PCR
- 6.2.6 Cloning and sequence analysis
- 6.3 RESULTS
- 6.3.1 Electron microscopy
- 6.3.2 Histopathology
- 6.3.3 Real-time PCR
- 6.3.4 Cloning and sequencing
- 6.4 DISCUSSION
- 6.5 REFERENCES
- CHAPTER SEVEN: CONCLUSION
