Browsing by Author "Young, Marion Belinda."

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Community radio and community representation : a case study of Highway Radio.
(2002) Mjwacu, Thembisa.; Young, Marion Belinda.
The community broadcasting in South Africa has been accredited with a different mandate from public and commercial broadcasting. This mandate of 'difference' has been stimulated by socio-political conditions under which this sector has been instituted since the early 1990s. During this period, conferences and discussions were held around the liberation of media and airwaves, which directly led to the recognition of the importance and the role that could be played by the community broadcasting sector. This sector of broadcasting is still a new concept in South Africa. Ten years post apartheid; it is no longer defined as a voice for political activism, as it was during its inception. Firstly, its development stages have bent towards a focus in the development of previously disadvantaged communities. Secondly, community radio has been regarded as a way of democratising media, by making it accessible to marginalised and underrepresented communities. It becomes a tool through which they voice out 'who they are' (identity) and also an instrument with which they initiate their own development and empowerment, socially and culturally. The research paper traces the development stages of this sector in South Africa, chronologically from its conception in the 1990s, to its mushrooming from 1994 and its functioning in the late 1990s to the early 21st century. The paper explores the sociopolitical roots of community radio in the face of change from democracy to technocracy. The responsibility of the community media sector includes the fulfillment of participation and media democratisation themes. The theoretical framework discussed by Dennis McQuail (1987, 1994, 2000) under normative theories of the media and development communication theories anaysed by Srinivas Melkote (1991), Jan Servaes (1991), Fred Casmir (1991), also form part of this paper. This paper, with an understanding of the demand for the democratization of the media and airwaves during this period in our country's history, explores how a chosen community radio becomes a public and community representative in the media industry. It focuses on representation of the community by the radio station in its management and functioning. It takes as a case study Highway Radio station. Highway Radio defines itself as a Christian radio station, which broadcasts from Pinetown and reaches Durban and surrounding urban and township areas. The general objective of this paper is to discover a set of indicators that provide a background to which Highway Radio has been able to fulfill its mandate as a community service. This study aims at exploring the active application of the notion of community participation in management and running of the radio station. The democratic-participant media theory stipulates that media must be spearheaded by active participation while the NCRF (National Community Radio Forum) also stipulates that community radio is characterized by active participation in all the structure of its organization. This research, therefore, has been conducted to explore the possibility and applicability of these prerequisites.
Developing an energy evaluation protocol for horse feeds in South Africa.
(2004) Lindsay, Elaine.; Young, Marion Belinda.
The purpose of this study was to find the most accurate and reliable method available in South Africa to evaluate equine diets on an energy basis. Currently South African horse owners purchase food according to the crude protein content of the diet, not knowing the energy density of the diet, which they are feeding their animals. Energy is one of the most important measures of an animal feed, as the energy density determines how much of a diet needs to be fed to meet an animal's requirement. The level of feed intake determines the concentrations of all other nutrients in the diet, therefore one cannot formulate a diet correctly without knowledge of its energy content. Through domestication, there has been an increased demand for horses to perform under circumstances that require energy greater than that provided by its natural diet of grass alone. This has therefore lead to the inclusion of cereal grains and their by-products. These large grain meals can overwhelm the digestive capacity of the horse thus leading to various types ofdigestive disorders such as colic. Therefore by the development of an energy evaluation system, one could provide the horse with the correct amount of energy from the appropriate source without compromising its digestive system. Predicting digestibility of a diet is the basic step for energy evaluation of horse feeds. Currently horse diets in South Africa are formulated using ruminant total digestible nutrient (TDN) data. As large horses are difficult to work with in digestibility trials, a preliminary experiment was designed to see how accurate it would be to use miniature horses as predictors of digestible energy for large horses. By comparing the digestibility data with that of overseas predictive equations, where large horses were used, the results were found to be highly comparable. As it was established that miniature horses were a perfect pilot animal for digestibility studies on large horses, the next step was to determine the rate of passage in miniature horses so as to determine if the length of the collection period, in a digestibility trial, proposed by overseas researchers for large horses, was enough time to clear the digestive system in a miniature horse of the diet under investigation. An experiment was carried out using Celite® as an insoluble marker to determine rates of passage via the acid insoluble ash method. A mean retention time of 66.64 hours was obtained, therefore assuring that a collection period of 5 days, as recommended by overseas researchers, was sufficient time to clear the miniature horse's digestive system of the test diet. Following the preliminary trial, a digestibility experiment was designed to investigate the accuracy of using ruminant data to formulate equine diets as well as using rabbits as a possible pilot animal in horse digestibility trials. The trial involved five miniature horses, four male sheep and ten rabbits. Four commercial horse diets were investigated. From these results it was found that rabbits proved difficult too work with and did not favour the experimental conditions and therefore gave digestibility results very different to that of the equine. Ruminants proved accurate predictors of the digestibility of the fibre components for horses but not for the other digestible nutrients. Significant differences were found between the diets given only to the horses and diets that should have provided a higher digestible energy did not. This accentuates the need for the development of an energy evaluation protocol, so that equine diets can be formulated more precisely and thereby ensure that the energy requirements of the horse are met. In vivo digestibility results were compared to the same feeds incubated in vitro and significant differences (P<0.05) were found between the results obtained by the two methods. A possible reason for this could be the method employed for removing supernatant between the two stages of the Tilley and Terry (1963) method, leading to an overestimation of digestibility for feeds containing hay and incubated in vitro. No significant differences (P>0.05) were found between digestibilities, rates and maximum gas production between the sources of inoculum used. Significant differences (P<0.05) were found between digestibilities obtained by incubating concentrates alone or in an 80:20 ratio with hay. Further investigation is needed here as it was felt that the supernatant removal method contributed significantly to inaccurate in vitro results. This experimental work centres on discovering and developing the best method available to the South African feed industry for predicting digestible energy contents of horse feed, so as to improve defined performance within an equine discipline and reduce nutritionally-induced disorders.
Development of a protocol for the molecular serotyping of the African horse sickness virus.
(2009) Groenink, Shaun Reinder.; Young, Marion Belinda.; Watson, Gregory M. F.
African horse sickness (AHS) is a viral disease with high mortality rates, vectored by the Culicoides midge and affecting members of the Equidae family. AHS is endemic to South Africa, and, as a result, affects export and international competitiveness in equine trade, and impacts significantly on the South African racehorse and performance horse industries. AHS also has devastating consequences for rural and subsistence equine ownership. The protocol developed in this dissertation has the potential to serotype and confirm the AHS virus within a few hours at significantly less cost than current methods. It will ease the financial and time constraints of studying an outbreak in real time and has the potential to solve many of the unknown factors surrounding AHS, particularly and most importantly, the role that each serotype plays in outbreaks and the form of the disease contracted by horses.
The effects of nutritional management on behaviour in thoroughbred racehorses.
(2007) Hackland, Jean.; Young, Marion Belinda.; Gous, Robert Mervyn.
This dissertation is the product of two behaviour studies and an in vitro fermentation trial. Both behaviour studies were conducted at the Ashburton Racehorse-Training Centre in Ashburton, near Pietermaritzburg in KwaZulu- Natal. The first behaviour study evaluated differences in behaviours obtained through feeding either twice or four times daily. This trial showed (P
An evaluation of effective energy in the formulation of diets for laying hens.
(1998) Young, Marion Belinda.; Gous, Robert Mervyn.
Emmans (1994) introduced a concept of energy utilisation applied across species, in which a heat increment in feeding is considered to be linearly related to five measurable quantities. Subtracting the heat increment of feeding from the metabolisable energy supplied defines the energy supply scale called effective energy. Two trial protocols were developed and run in controlled environment chambers at hot and cold temperatures using laying hens in individual cages. The first trial tested the response of hens at temperatures of 18°C and 32°C to the dilution of a basal diet with ingredients selected to promote a heat increment in different manners, according to the effective energy system. Diluents were soy protein isolate, fishmeal, sunflower oil, husks and sugar and starch mix. Six diets were offered to Amberlink and Hyline Brown hens for two successive periods of six weeks at the two temperatures. Responses in performance and calculated heat production indicated that heat increments could be induced by particular diluents. These affected the response in laying performance of the birds, particularly at high environmental temperatures. A second protocol tested the absolute value of the effective energy system by using Amber link hens for three consecutive seven week periods at 30°C, 20°C and 30°C, respectively. High and low effective energy diets were formulated, and blended, and compared against commercial high and low density diets. The effective energy diets and the commercial diets were also offered as a choice to the hens. The data illustrate a marked linear response to the effective energy in the diet. High effective energy produced the same response as a high nutrient density at high temperatures. Highest performances in lay were achieved on the choice diets. The hens demonstrated the ability to change the proportion of the choice of the effective energy diets at the different temperatures. Dynamic heat exchanges with the environment become significant, especially at higher temperatures in the thermally active hen. Effective energy considers this heat response, and can assist in ameliorating the response of the laying hen to high environmental temperatures when incorporated into principles of feed formulation.
An evaluation of growth and symmetry in thoroughbred foals and Holstein calves.
(2008) Halgreen, Sarah.; Young, Marion Belinda.; Nsahlai, Ignatius Verla.
Holstein calves were photographed and measured over a period of 84 days to determine the feasibility of Image Analysis as a measurement tool. It was determined that the disparity between actual measurements and image analysis measurements decreased as the bone length increased, and that image analysis could be used to monitor growth successfully in large ungulates, using the length of certain bone. Image analysis was then used to evaluate growth in Holstein calves on two weaning programs (weaned early at six weeks of age and weaned later at eight weeks of age). Calves were weighed and photographed over a period of 224 days to determine the effects of weaning on skeletal symmetry. Weaning time did have an affect on the skeletal symmetry of the calves, with calves weaned earlier found to be more asymmetrical. The extent to which skeletal symmetry is affected by a stress is determined by the nature and duration of the stress. The growth and development of Thoroughbred foals was recorded and photographed for a period of 300 days and the relative asymmetry for bilateral traits was assessed. Thoroughbred foal growth correlated to statistics reported over the last twenty eight years. Asymmetry can be detected in growing foals using image analysis. Weaning stress produced some asymmetry that the foals were able to recover from. One can use highly correlated body weight and height measurements to produce a tool stud managers can used to monitor growth. In young training Thoroughbreds (between 18 and 24 months of age), no significant asymmetry was found in the forelimbs but the hind legs displayed asymmetry, which has interesting implications for training and for performance criteria in the racehorse. Tools can be produced to monitor the growth and development of Thoroughbred foals destined to race, which can improve their management and the duration of their racing careers.
Improving the nutritional representation of horse feeds in South Africa.
(2011) Young, Marion Belinda.; Laing, Mark Delmege.
Protein has been identified as a major reason that people purchase a horse feed, with anecdotal explanations offered for the poor prediction of response of horses to their rations, particularly in the sport horse market. The current research identifies through hierarchical cluster analysis that the myriad of riding feeds offered on the South African market fall into only four simple categories on the basis of wet chemistry. Feeds were subjected to the in vitro gas production technique (IVGPT) described by Pell and Schofield (1993), using equine faecal inoculum. Gas profiles, corrected for control fermentation profiles in the absence of substrate, were fitted to the model described by Campos et al. (2004) to derive GP kinetics. Gas production kinetics, and information in respect of pH, degradation efficiency, lag time and apparent and true digestibilities were obtained. The feeds were tested for glycaemic response in miniature horses using the hexokinase method with deproteinization using an auto analyser (Roche Diagnostics). Blood glucose parameters of feeds (mean, peak, slope and time to peak and area under the curve) in each group were compared by analysis of variance and regression with covariates. In vivo analysis of rates of passage and digestibility using using post-prandial percentages of acid insoluble marker collection was used to study the gastrointestinal process, to indicate foregut and hindgut compartmental flow. The need to balance nitrogen levels with a proportional supply of fermentable carbohydrate contradicts widely used protein intakes in the horse. In vitro fermentation was used in an analysis of nutrient synchrony, to identify optimal fermentative capacity for utilization of horse feeds. The characteristics of horse feeds were related to requirement and were composited in an analysis of the representation of horse feeds that would best reflect optimal utilization in the horse, to produce a method of feed characterisation that would lead to the optimal prediction of response of horses to feeds offered to South African horses.
Mineral and nutrient evaluation of horse feeds and fodder in South Africa.
(2015) Horne, Sheldene Kerry.; Young, Marion Belinda.
Little information is available on the nutrient, and particularly the mineral provision of fodder and feed in the South African horse industry. Rational feeding models are not applied, and inadequacies in the ration are compensated for by increments in concentrate feed intake. This constitutes a violation of nutritional physiology in the hindgut fermenter, and consequences of high concentrate feeds are discussed. Nutrient provision from the fodder portion of the ration is not considered when feed formulation and raw material selection occur. Consequently, feed and fodder samples were collected from a variety of sources and subjected to mineral and nutrient analyses to elucidate the extent of the problem as it pertains to the meeting of requirements in horses of different life stages and work rates. 99 fodder samples were analysed and Principle Component Analyses (PCA) were conducted. Three statistically diverse groups of fodder were identified - kikuyu and lucerne contain high digestible energy and crude protein content which differentiates them from other grasses. Mineral provision from the three groups is diverse. There is justification for developing fodder specific feeds for horses based on these fodder types. 64 concentrate horse feeds were analysed by PCA to determine groups of similar nutrient content. Balancer and fibre feeds could be differentiated from other feeds based on their fibre and CP content. The balance of the feeds could not be segregated into their life stage or work purpose groups and statistically fell into the same feed group. Correlation matrices between advertised and actual nutrient content revealed inconsistencies between feed factories. Mineral provision in the feeds is a function of the factory they are produced in and not as a function of the life stage and work purpose of the feeds. Major mineral provision in horse feed is erratic and 15 out the 64 feeds exhibited inverse Ca:P ratios and very few have sufficient Mg to balance the Ca:Mg ratio required by horses. Horse feeds contain excess Fe and are often deficient in Cu and Zn while Mn provision is adequate. It is evident that brand or factory plays a more important role in mineral nutrition of horses, than life stage or work rate. Feed formulation strategies appear to be least cost based with little regard for horse requirements evident in the final feed products. Ration evaluation revealed that grasses are able to provide sufficient DE and CP for horses in light work while kikuyu and lucerne can support horses up to the moderate work category. All fodder types require mineral supplementation to provide absolute mineral levels and balance between minerals to horses. A comparison of five equine life stage reconstituted rations were then constructed and work ration scenarios demonstrated that DE and CP provision in most instances was sufficient, although CP overprovision did occur. Mineral levels were erratic and in the stud and race groups, feeds produced inverse Ca:P ratios. This could affect skeletal integrity and cause lameness – two issues often found in racehorses, leading to wasted training days and horse breakdowns. Major overprovision of Fe occurs in all the rations with concomitant deficiencies of Cu and Zn. This imbalance could have negative consequences in the horse in terms of immune and anti-oxidant systems. It is evident from the study that feeds are poorly formulated and feeding strategies currently employed in SA are flawed in their provision of health-promoting nutrition to horses. New strategies and feed formulation goals need to be investigated and the feeding of horses in SA needs to be restructured to respect the horse as a hindgut fermenter with an absolute requirement for fodder and to provide correct mineral balance in rations.
Molecular diagnosis of African horse sickness.
(2018) McColl, Evan Saul.; Laing, Mark Delmege.; Burgdorf, Richard Jörn.; Young, Marion Belinda.
African horse sickness (AHS) is a viral disease of equids caused by the African horse sickness virus (AHSV), a double-stranded RNA virus of the genus Orbivirus. The disease had a devastating effect on the sporting horse industry, and many communities who rely on equids for subsistence farming. In this study, which started in 2016, blood samples were collected from 81 horses in the KwaZulu Natal province of South Africa. Six horses (7%) were identified as AHSV positive and had their viral load quantified using a standard RT-qPCR assay. A semi-quantitative method, using digital gel image analysis, was evaluated as an alternative to qPCR in resource-limited settings. A significant correlation was found in the quantification data obtained using qPCR and digital gel analysis (P < 0.01), demonstrating the potential for its use in under-equipped diagnostic laboratories. Vaccination is currently the main tool for control of AHS in endemic areas. Live attenuated vaccines (LAV) have the potential to disrupt effective disease monitoring by being a source of the detectable virus. The sensitivity of nucleic acid diagnostic assays allows for the detection of low levels of AHSV prior to the onset of clinical signs. A study was conducted on the effect that this vaccine has on viraemia levels and the disruptive effect this may have is discussed. Routinely vaccinated miniature mares (n=9) had their AHSV viraemia levels monitored following the use of a commercial polyvalent LAV. No AHSV was detected in the horses following vaccination. The absence of AHSV in the mares supports the concept that multiple vaccinations reduce the risk of vaccine-induced viraemia. Flinders Technology Associates® filter paper cards (FTA® cards) are designed to store nucleic acid from fresh sample material in a stable matrix and may be a practical solution to disease surveillance in resource-limited settings, where conventional sampling methods are not always suitable. Storage and elution conditions of AHSV RNA from these cards have yet to be investigated. This study compared the efficacy of two elution reagents for AHSV RNA extraction from blood applied to FTA® cards. Cards with AHSV positive blood applied were stored at room temperature for one week. Amplified products were extracted using TE-buffer with an elution time of 24 hours. This study shows that FTA® cards are feasible for AHSV nucleic acid assays but further investigation into standardised procedures for the storage and recovery of AHSV RNA from FTA® cards is required. The AHSV genome is made up of ten double-stranded RNA segments with nine antigenically different serotypes of AHSV identified so far. However, there is limited information on the serotype prevalence of AHSV in endemic areas. Therefore, multivalent vaccines remain the mainstay for disease control in these regions. Improved epizootiological information can improve vaccination programs and control mechanisms. In this experiment, a novel approach was investigated for the assessment of AHSV nucleic acid variations using high-resolution melt analysis (HRMA). Blood infected with a wild strain of AHSV was used in a PCR that targeted regions of Segment 10 (S10) and Segment 2 (S2). Following this, high-resolution melting curves were generated from these PCR products. S10 primers amplified the expected 181 bp product but the other primer sets failed to amplify the S2 gene segment, warranting further evaluation and optimisation of the primer sets used to detect currently circulating AHSV strains.
The potential contribution of a sustainable organic household food garden to vitamin A and vegetable needs of sampled low-income households, KwaZulu-Natal.
(2003) Makhotla, Likeleli.; Hendriks, Sheryl Lee.; Green, Jannette Maryann.; Chitja, Joyce Magoshi.; Young, Marion Belinda.
Vitamin A deficiency is a worldwide public health problem. In South Africa, in 1999, 62 to 70 percent of children in rural areas and 48 to 62 percent in urban areas consumed less than half the recommended dietary allowance for vitamin. A. This study set out to investigate the potential contribution of home gardens to the vitamin A and vegetable needs of low-income households, especially in rural areas. The study problem was to develop a model of a sustainable household food garden to ensure adequate supply of vitamin A rich vegetables to meet the vitamin A requirements of low-income households throughout the year. The study subproblems included: first, to develop an organic household food garden unit to provide adequate vitamin A and vegetables for households. Second, to test the feasibility of the garden unit among sample households in two study areas. Third, to test vitamin A and vegetable adequacies of the garden unit for the sample households. A survey of 52 households from Department of Agriculture communal garden projects in Cuphulaka and Mlwandle in KwaZulu-Natal was conducted. The sample households were participants in communal gardens, but the survey dealt with household production only. Data included household demographics, types of vegetables grown, garden sizes, gardening practices, the socio-economic and environmental constraints of home gardening and the food frequency consumption. The garden unit was developed from a review of literature regarding best practice of organic production of vitamin A rich vegetables. The garden unit was demonstrated to the study participants and their perceptions of the unit were measured in discussion groups to test the acceptance and feasibility of the household garden. Data on household demographics and frequency of vegetable consumption was used to measure adequacy of vitamin A consumed by households and to test adequacy of vitamin A and vegetables from the garden unit. Most participants depended mainly on communal garden projects for vegetables. Although access to land seemed not a problem, few sample households practiced home gardening. Water scarcity and lack of fencing were frequently reported as constraints of home gardening by sample households who perceived home gardening as a cost-effective way of diversifying and adding nutrients to family diets. However, vegetable production in home gardens was characterised by low yields and seasonal availability. The potential of the household food gardens to increase vegetable production was found feasible by sample households. No significant difference was identified in vegetable consumption of households with and without home gardens. In fact, participation in communal gardens does not increase the vegetable consumption of sample households, which may be the result of no or low production and poor eating habits. The study assumed that rural households should consume at least 33 percent of RDA of vitamin A from vegetables, yet many sample households consumed less than this. Sample households could obtain enough vitamin A and vegetables from the garden unit/s, and in many cases they could have surpluses. Recommendations include the integration of home gardening in government strategies and integration of nutrition education in programmes that aim at increasing vegetable production in communal and home gardens in study areas.
Prophylactic strategies in the control of African horse sickness.
(2008) Simpkin, Tarryn Lyn.; Young, Marion Belinda.
African horse sickness (AHS) is a non-contagious viral disease transmitted by an arthropod vector and is endemic to sub-Saharan Africa. The disease affects all equine species, but is more severe in horses and other equid species not native to Africa. Vaccination is the only demonstrated means of its prevention. The horse-owning public provides much anecdotal evidence of prophylactic strategies, such as repellents, stabling, alternate hosts, traps, paraffin, blankets, smoke or fans. The present study investigated the relationship of these strategies to the incidence of AHS, and evaluated alternate hosts, wind speed and repellents on the activity of males and females of the different Culicoides species.. Cypermethrin and citronella-containing repellents repelled the most female midges. Sheep and cattle offer an alternate blood meal to gravid and nulliparous female midges. Fans are very effective in keeping midges away from horses. Methods are summarised for the horse owner to implement in addition to vaccination to prevent AHS.
Statistical analysis of the incidence and mortality of African horse sickness in South Africa.
(2011) Burne, Rebecca.; Mwambi, Henry G.; Young, Marion Belinda.
No abstract available.
A study of the African horse sickness virus using High Resolution Melt, multivariate and phylogenetic analyses for a potential serotyping assay.
(2014) Groenink, Shaun Reinder.; Coetzer, Theresa Helen Taillefer.; Young, Marion Belinda.; Watson, Gregory M. F.
African horse sickness (AHS) is a viral disease that afflicts all equine species and has a 90% mortality rate in unvaccinated horses. The disease has a devastating effect on the national herd of South Africa each year and affects both the sport and racehorse industries, including the export of prized bloodstock, as well as the rural and subsistence economies that depend on animal traction. Transmitted by the Culicoides spp. of biting midge, the virus belongs to the Orbivirus genus of the Reoviridae family with nine known serotypes and ten genome segments. Segment 2 (which encodes VP2) is responsible for serotype determination while segment 10 (which encodes NS3) is merely serotype-divergent. Knowledge of the seroprevalence of the virus is poor. The increasing reluctance of horse owners to use the registered vaccine due to perceived inefficacy is of concern. As a means to increase knowledge output in this regard, and potentially provide a service to horse owners, a rapid serotyping assay is sought based on High Resolution Melt (HRM) analysis. HRM analysis is a powerful tool that is based on the release of a DNA intercalating dye from polymerase chain reaction products through gradual and controlled heating. The dye is released at a specific point that is dependent on the unique sequence of the amplicon. It can thus be used to distinguish, very sensitively, differences in divergent amplicons. Using a range of freely available bioinformatics software, such as Clustal X2, Primaclade, Treeview and BLAST analysis, primers were designed based on segment 2 that sought to differentiate the individual serotype from previously defined clades based on a pair of segment 10 primers. Reference and field isolates of the AHS virus were obtained from the National Institute of Communicable Disease and the Onderstepoort Veterinary Institute, South Africa, and were propagated on Vero cell monolayers. Total RNA was extracted using guanidine-thiocyanate and verified as containing AHSV genomic material using primers recognised by the World Organisation for Animal Health that target the genome segment encoding VP7. Variable amounts of total RNA did not influence the downstream analysis as individual serotypes were easily distinguished using HRM despite wide ranging template concentrations. Through testing the primers designed in the present study, various serotype anomalies were discovered with regard to the isolates obtained from the Onderstepoort Veterinary Institute. Serotype-specific primers and the segment 10 primers were used to interpret the serotype anomalies through High Resolution Melt analysis. Sequencing confirmed the anomalies: serotype 2 isolates were serotype 6 isolates and a serotype 5 isolate was serotype 8. A proposed protocol for a rapid serotyping assay was investigated. This involved an initial PCR to determine into which clade of segment 10 the sample fits. Following this, the serotype was elucidated for each clade using segment 2 clade-specific primers. These reactions were performed in the Corbett Rotor-Gene™ 6000 and its in-built software was used. However, limitations of the software soon became apparent, as it was not able to completely distinguish the serotypes. Alternate methods were sought and included ScreenClust HRM® Software, principal component analysis (PCA) and discriminant analysis (DA). The use of normalised HRM fluorescence curves for PCA and DA was effective in standardising the template concentrations. These methods were successful in determining the serotype and rendered results with greater statistical confidence. Finally, a phylogenetic analysis was performed of all the available AHS virus sequences to determine the degree of possible genetic drift in the virus that may give rise to a new serotype. Minimal to no genetic drift could be found comparing sequences from the 1960s to sequences from the 2000s. This study presents the ability of HRM analysis to recognise and define AHS virus serotype anomalies, provide a new protocol for the serotyping of the virus with an extensive statistical analysis, the first for an orbivirus. Furthermore, the protocols described can be extrapolated to other orbiviruses.
Testing for passive transfer of immunity in foals, and an evaluation of the African horse sickness vaccination schedule.
(2005) Crow, Linnet Jean Isobel.; Young, Marion Belinda.; Bradford, Gail Smith.
This thesis comprises an introductory review of the literature, followed by reports of two experiments which are presented in the form of scientific papers. For this reason, there may be some repetition between chapters, particularly in terms of experimental procedure. To avoid unnecessary repetition, a single list of references is given at the end of the thesis. For the sake of completeness , several appendices are attached to Chapters Two and Three which would not ordinarily be included in a scientific paper. The literature review looks at the passive transfer of immunity from the mare to the foal, the consequences of failure of passive transfer of immunity and different methods of testing whether the transfer of passive immunity has occurred. The review concludes with a discussion of vaccination programmes against African horse sickness. Trial One evaluated different tests for determining whether the transfer of passive immunity from mare to foal has occurred in order to determine which of these tests should be used preferentially. A single radial immunodiffusion test was used as the reference standard. A series of samples .was taken from a group of foals and tested using four methods: single radial immunodiffusion , glutaraldehyde coagulation, zinc sulphate turbidity and protein refractometer tests. Trial Two explored African horse sickness vaccination programmes, focusing on when to vaccinate foals for the first time. A series of samples was taken from a group of foals from birth until two months after their second set of African horse sickness vaccinations (one year old). The samples were tested for the presence of African horse sickness antibodies for each of the nine serotypes to determine when maternal immunity fades and to evaluate the effect of each vaccination on the level of immunity.