The feasibility of task-shifting prolonged exposure for Primary Care (PE-PC) for PTSD within a low resource community in the Eastern Cape
- Shabangu, Princess Noxolo Nonhlanhla
- Authors: Shabangu, Princess Noxolo Nonhlanhla
- Date: 2024-04-04
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/435479 , vital:73161
- Description: Although high levels of trauma exposure potentiate an alarming prevalence of PTSD, increasing the need for trauma-focused treatment, the South African health system is unable to care for the population. The South African healthcare system contains a range of systemic and structural inefficiencies, including suboptimal care and shortages of healthcare professionals. PE-PC offers a resource-constrained mental healthcare system solution by integrating an evidence-based intervention (EBI) in primary care settings. Likewise, the present study acknowledges the ratio of mental healthcare professionals to patients in low- and middle-income countries (LMIC). It explores task shifting to expand mental healthcare to primary care settings. The study follows qualitative healthcare design research to explore the experiences and perceptions of the two cohorts of trauma support workers (TSW) from Rhode University and the Joza community in Makhanda. The feasibility of the PE-PC intervention in Makhanda was illustrated through the data obtained from the TSWs' experiences and perceptions of the intervention's utility. The present study presents an essential contribution to the sparse research conducted on treating PTSD in LMIC with shortages in healthcare professionals. The thematic findings look at the trauma support workers (TSWs) role, including some of its challenges, to explore the feasibility of interventions. Some of the themes highlighted unpack the perceived utility of task-shifting in low-resource contexts, the limitations thereof and considerations for future research. Notwithstanding the challenges, the data from the present study indicates that PE-PC can be feasibly task-shifted in low-resource contexts such as Makhanda. , Thesis (MA) -- Faculty of Humanities, Psychology, 2024
- Full Text:
- Date Issued: 2024-04-04
- Authors: Shabangu, Princess Noxolo Nonhlanhla
- Date: 2024-04-04
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/435479 , vital:73161
- Description: Although high levels of trauma exposure potentiate an alarming prevalence of PTSD, increasing the need for trauma-focused treatment, the South African health system is unable to care for the population. The South African healthcare system contains a range of systemic and structural inefficiencies, including suboptimal care and shortages of healthcare professionals. PE-PC offers a resource-constrained mental healthcare system solution by integrating an evidence-based intervention (EBI) in primary care settings. Likewise, the present study acknowledges the ratio of mental healthcare professionals to patients in low- and middle-income countries (LMIC). It explores task shifting to expand mental healthcare to primary care settings. The study follows qualitative healthcare design research to explore the experiences and perceptions of the two cohorts of trauma support workers (TSW) from Rhode University and the Joza community in Makhanda. The feasibility of the PE-PC intervention in Makhanda was illustrated through the data obtained from the TSWs' experiences and perceptions of the intervention's utility. The present study presents an essential contribution to the sparse research conducted on treating PTSD in LMIC with shortages in healthcare professionals. The thematic findings look at the trauma support workers (TSWs) role, including some of its challenges, to explore the feasibility of interventions. Some of the themes highlighted unpack the perceived utility of task-shifting in low-resource contexts, the limitations thereof and considerations for future research. Notwithstanding the challenges, the data from the present study indicates that PE-PC can be feasibly task-shifted in low-resource contexts such as Makhanda. , Thesis (MA) -- Faculty of Humanities, Psychology, 2024
- Full Text:
- Date Issued: 2024-04-04
Empty adjectives and excessive intensifiers, or savvy discourse moves? A feminist critical discourse study of gender-based differences in the discourse of businesspeople on LinkedIn
- Authors: Schmauss, Lindsay Susannah
- Date: 2023-10-13
- Subjects: Corpora (Linguistics) , Critical discourse analysis , Intensification (Linguistics) , Women's language , Adjective , Politeness (Linguistics)
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/425111 , vital:72211
- Description: This Feminist Critical Discourse Analysis (FCDA) examines the use of ‘empty’ adjectives and the equative intensifier so in discourse on LinkedIn, a social network service (SNS) for businesspeople and professionals. These linguistic features soften the impact of what is said in ways that can conform with politeness norms that one should not impose a point of view but can also be negatively construed as weak, uncertain and unclear. The North American sociolinguist, Robin Tolmach Lakoff (1973, 1975, 2004), first associated these linguistic markers with a feminine register in her seminal work, Language and Women’s Place, arguing that there is a social expectation that women talk like a lady and follow politeness conventions, while the speech of men is not similarly constrained. That women are socially conditioned to speak in ways that can undermine their clarity and assertiveness would present a particular dilemma in the business context, where clear, direct and confident communication is valued. This corpus-based study explores the dilemma in the context of LinkedIn where the linguistic behaviour of cisgender women indeed showed evidence of their struggle between conflicting impulses to talk like a lady and a desire to be taken seriously as businesspeople. While the examined features mainly appeared in the discourse of women, it was interesting to note men making use of ‘empty’ adjectives and so in communication contexts where the goal appeared to be relationship-building. As notions of business leadership are evolving to value organisational leadership more, this suggests that linguistic devices that have traditionally been associated more with the communal conversation of the stereotypical ‘woman’ appear to be gaining wider acceptance and relevance, although in domains orientated towards the “soft skill” of building relationships, rather than the “hard work” of business. While the value talking like a lady may be shifting, language that is the opposite of talking like a lady seems to remain the language of serious talk, and the kind of gender-based linguistic discrimination first theorised by Lakoff seems thus to persist, also in the sphere of business discourse. , Thesis (MA) -- Faculty of Humanities, Linguistics and Applied Language Studies, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Schmauss, Lindsay Susannah
- Date: 2023-10-13
- Subjects: Corpora (Linguistics) , Critical discourse analysis , Intensification (Linguistics) , Women's language , Adjective , Politeness (Linguistics)
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/425111 , vital:72211
- Description: This Feminist Critical Discourse Analysis (FCDA) examines the use of ‘empty’ adjectives and the equative intensifier so in discourse on LinkedIn, a social network service (SNS) for businesspeople and professionals. These linguistic features soften the impact of what is said in ways that can conform with politeness norms that one should not impose a point of view but can also be negatively construed as weak, uncertain and unclear. The North American sociolinguist, Robin Tolmach Lakoff (1973, 1975, 2004), first associated these linguistic markers with a feminine register in her seminal work, Language and Women’s Place, arguing that there is a social expectation that women talk like a lady and follow politeness conventions, while the speech of men is not similarly constrained. That women are socially conditioned to speak in ways that can undermine their clarity and assertiveness would present a particular dilemma in the business context, where clear, direct and confident communication is valued. This corpus-based study explores the dilemma in the context of LinkedIn where the linguistic behaviour of cisgender women indeed showed evidence of their struggle between conflicting impulses to talk like a lady and a desire to be taken seriously as businesspeople. While the examined features mainly appeared in the discourse of women, it was interesting to note men making use of ‘empty’ adjectives and so in communication contexts where the goal appeared to be relationship-building. As notions of business leadership are evolving to value organisational leadership more, this suggests that linguistic devices that have traditionally been associated more with the communal conversation of the stereotypical ‘woman’ appear to be gaining wider acceptance and relevance, although in domains orientated towards the “soft skill” of building relationships, rather than the “hard work” of business. While the value talking like a lady may be shifting, language that is the opposite of talking like a lady seems to remain the language of serious talk, and the kind of gender-based linguistic discrimination first theorised by Lakoff seems thus to persist, also in the sphere of business discourse. , Thesis (MA) -- Faculty of Humanities, Linguistics and Applied Language Studies, 2023
- Full Text:
- Date Issued: 2023-10-13
A model to predict the development of preeclampsia in South African women
- Authors: Smith, Nathan
- Date: 2022-12
- Subjects: Medical instruments and apparatus -- Design and construction , Hypertension in pregnancy -- measurements-- South Africa , Fetus -- Physiology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/59980 , vital:62724
- Description: Preeclampsia is the new onset of hypertension and is one of the leading causes of maternal mortality in South Africa and the world. Preeclampsia is usually diagnosed after 20 weeks’ gestation. Due to South Africa’s poor level of antenatal care, the prediction of pregnant women at risk of developing preeclampsia can be an essential component of improving the level of antenatal. This study used an antenatal care dataset from a South African obstetrician. A review of the literature and existing systems was conducted to identify the eight risk factors. These risk factors are systolic blood pressure, diastolic blood pressure, maternal age, body mass index, diabetes status, hypertension history, nulliparity, and maternal disease. This study used antenatal care datasets from a South African obstetrician. Two models were developed that could accurately predict the development of preeclampsia, one before 16 weeks’ gestation and the other within three check-ups. The model was evaluated using five evaluation metrics: classification accuracy, area under the curve, precision, recall and F-Score. The results of this study show a promising future for the use of machine learning models in health care. To the researcher’s knowledge, this model is the first machine learning model for predicting preeclampsia using a South African dataset. Future work will revolve around validating the model on data collected from field studies in hospitals and clinics around South Africa , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2022
- Full Text:
- Date Issued: 2022-12
- Authors: Smith, Nathan
- Date: 2022-12
- Subjects: Medical instruments and apparatus -- Design and construction , Hypertension in pregnancy -- measurements-- South Africa , Fetus -- Physiology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/59980 , vital:62724
- Description: Preeclampsia is the new onset of hypertension and is one of the leading causes of maternal mortality in South Africa and the world. Preeclampsia is usually diagnosed after 20 weeks’ gestation. Due to South Africa’s poor level of antenatal care, the prediction of pregnant women at risk of developing preeclampsia can be an essential component of improving the level of antenatal. This study used an antenatal care dataset from a South African obstetrician. A review of the literature and existing systems was conducted to identify the eight risk factors. These risk factors are systolic blood pressure, diastolic blood pressure, maternal age, body mass index, diabetes status, hypertension history, nulliparity, and maternal disease. This study used antenatal care datasets from a South African obstetrician. Two models were developed that could accurately predict the development of preeclampsia, one before 16 weeks’ gestation and the other within three check-ups. The model was evaluated using five evaluation metrics: classification accuracy, area under the curve, precision, recall and F-Score. The results of this study show a promising future for the use of machine learning models in health care. To the researcher’s knowledge, this model is the first machine learning model for predicting preeclampsia using a South African dataset. Future work will revolve around validating the model on data collected from field studies in hospitals and clinics around South Africa , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2022
- Full Text:
- Date Issued: 2022-12
A systematic methodology to evaluating optimised machine learning based network intrusion detection systems
- Authors: Chindove, Hatitye Ethridge
- Date: 2022-10-14
- Subjects: Intrusion detection systems (Computer security) , Machine learning , Computer networks Security measures , Principal components analysis
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/362774 , vital:65361
- Description: A network intrusion detection system (NIDS) is essential for mitigating computer network attacks in various scenarios. However, the increasing complexity of computer networks and attacks makes classifying unseen or novel network traffic challenging. Supervised machine learning techniques (ML) used in a NIDS can be affected by different scenarios. Thus, dataset recency, size, and applicability are essential factors when selecting and tuning a machine learning classifier. This thesis explores developing and optimising several supervised ML algorithms with relatively new datasets constructed to depict real-world scenarios. The methodology includes empirical analyses of systematic ML-based NIDS for a near real-world network system to improve intrusion detection. The thesis is experimental heavy for model assessment. Data preparation methods are explored, followed by feature engineering techniques. The model evaluation process involves three experiments testing against a validation, un-trained, and retrained set. They compare several traditional machine learning and deep learning classifiers to identify the best NIDS model. Results show that the focus on feature scaling, feature selection methods and ML algo- rithm hyper-parameter tuning per model is an essential optimisation component. Distance based ML algorithm performed much better with quantile transformation whilst the tree based algorithms performed better without scaling. Permutation importance performs as a feature selection method compared to feature extraction using Principal Component Analysis (PCA) when applied against all ML algorithms explored. Random forests, Sup- port Vector Machines and recurrent neural networks consistently achieved the best results with high macro f1-score results of 90% 81% and 73% for the CICIDS 2017 dataset; and 72% 68% and 73% against the CICIDS 2018 dataset. , Thesis (MSc) -- Faculty of Science, Computer Science, 2022
- Full Text:
- Date Issued: 2022-10-14
- Authors: Chindove, Hatitye Ethridge
- Date: 2022-10-14
- Subjects: Intrusion detection systems (Computer security) , Machine learning , Computer networks Security measures , Principal components analysis
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/362774 , vital:65361
- Description: A network intrusion detection system (NIDS) is essential for mitigating computer network attacks in various scenarios. However, the increasing complexity of computer networks and attacks makes classifying unseen or novel network traffic challenging. Supervised machine learning techniques (ML) used in a NIDS can be affected by different scenarios. Thus, dataset recency, size, and applicability are essential factors when selecting and tuning a machine learning classifier. This thesis explores developing and optimising several supervised ML algorithms with relatively new datasets constructed to depict real-world scenarios. The methodology includes empirical analyses of systematic ML-based NIDS for a near real-world network system to improve intrusion detection. The thesis is experimental heavy for model assessment. Data preparation methods are explored, followed by feature engineering techniques. The model evaluation process involves three experiments testing against a validation, un-trained, and retrained set. They compare several traditional machine learning and deep learning classifiers to identify the best NIDS model. Results show that the focus on feature scaling, feature selection methods and ML algo- rithm hyper-parameter tuning per model is an essential optimisation component. Distance based ML algorithm performed much better with quantile transformation whilst the tree based algorithms performed better without scaling. Permutation importance performs as a feature selection method compared to feature extraction using Principal Component Analysis (PCA) when applied against all ML algorithms explored. Random forests, Sup- port Vector Machines and recurrent neural networks consistently achieved the best results with high macro f1-score results of 90% 81% and 73% for the CICIDS 2017 dataset; and 72% 68% and 73% against the CICIDS 2018 dataset. , Thesis (MSc) -- Faculty of Science, Computer Science, 2022
- Full Text:
- Date Issued: 2022-10-14
Stable Covalent pH-Sensitive Metallophthalocyanines Thin Monolayer Films for Selective Detection of Neurotransmitters
- Idowu, Abosede Omowumi Atinuke
- Authors: Idowu, Abosede Omowumi Atinuke
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192922 , vital:45279
- Description: Thesis (PhD) -- Faculty of Humanities, Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Idowu, Abosede Omowumi Atinuke
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192922 , vital:45279
- Description: Thesis (PhD) -- Faculty of Humanities, Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29
A framework to measure employee engagement at Stefanutti Stocks RPM Business Unit
- Authors: Maher, Theresa
- Date: 2021-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53315 , vital:45142
- Description: Work gratification and expectancies are of the utmost importance to the skilled workforce in the South African construction industry. The price paid for a demotivated workforce in this industry is very high and it leads to friction in the workplace, displeasing work outcomes and time delays. Furthermore it leads to increased incidences of theft,absenteeism and outputs that arebelow standard in terms of productivityand thequality of the work.In order to motivate the workforce in the construction industry,a day-by-day, step-by-step,hands-on approachmust be used. The aforesaid aids site managers to manage effectively and this in turn leads to an increase in production by way of enhanced productivity. Research shows that a correlationbetweenmotivation, excelling at work, improved productivity and fulfilment and expectancyexist. The reason why individuals act in a specific manner and choose not to act in a certain way can be directly linked totheirmotivation and engagement.As a member ofthe construction industry in South Africa, Stefanutti Stocks isseen as one of the leading construction groups. Employing more than 12 000 workers it has the ability to provide a wide variety of different scale projects for a host of clients in varied markets. The division concentrated on in this study is the Roads, Pipelines and Mining Services (RPM)Business Unit. The MD of the RPM Business Unit when starting at the company a few years ago came to the conclusion that in order for the RPM Business Unit to function optimally certain business inconsistencies regarding employee engagement needed to be addressed. Based on this he decided to use a consulting firm, AIM,to establish what the exact concernswere and what interventions wererequired to deal with them. ivInterventions facilitatedby AIM includedManagement Training Programmes and Workshops as well as one-on-one coaching sessions with selected individuals.The methodology used in this study was to measurethe current level of employee engagement subsequent toengagement interventionsconcludedby AIM.The approach used was the use of surveys distributed through AIM in conjunction with the RPM Business Unit’sHR Department. The surveys were distributed via Survey Monkey Software owned by the RPM Business Unit of Stefanutti Stocks. , Thesis (MBA) -- Faculty of Business and Economic Sciences, NMMU Business School, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Maher, Theresa
- Date: 2021-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53315 , vital:45142
- Description: Work gratification and expectancies are of the utmost importance to the skilled workforce in the South African construction industry. The price paid for a demotivated workforce in this industry is very high and it leads to friction in the workplace, displeasing work outcomes and time delays. Furthermore it leads to increased incidences of theft,absenteeism and outputs that arebelow standard in terms of productivityand thequality of the work.In order to motivate the workforce in the construction industry,a day-by-day, step-by-step,hands-on approachmust be used. The aforesaid aids site managers to manage effectively and this in turn leads to an increase in production by way of enhanced productivity. Research shows that a correlationbetweenmotivation, excelling at work, improved productivity and fulfilment and expectancyexist. The reason why individuals act in a specific manner and choose not to act in a certain way can be directly linked totheirmotivation and engagement.As a member ofthe construction industry in South Africa, Stefanutti Stocks isseen as one of the leading construction groups. Employing more than 12 000 workers it has the ability to provide a wide variety of different scale projects for a host of clients in varied markets. The division concentrated on in this study is the Roads, Pipelines and Mining Services (RPM)Business Unit. The MD of the RPM Business Unit when starting at the company a few years ago came to the conclusion that in order for the RPM Business Unit to function optimally certain business inconsistencies regarding employee engagement needed to be addressed. Based on this he decided to use a consulting firm, AIM,to establish what the exact concernswere and what interventions wererequired to deal with them. ivInterventions facilitatedby AIM includedManagement Training Programmes and Workshops as well as one-on-one coaching sessions with selected individuals.The methodology used in this study was to measurethe current level of employee engagement subsequent toengagement interventionsconcludedby AIM.The approach used was the use of surveys distributed through AIM in conjunction with the RPM Business Unit’sHR Department. The surveys were distributed via Survey Monkey Software owned by the RPM Business Unit of Stefanutti Stocks. , Thesis (MBA) -- Faculty of Business and Economic Sciences, NMMU Business School, 2021
- Full Text:
- Date Issued: 2021-04
Effectiveness of cost containment measures: the case of Harry Gwala District Municipality
- Authors: Lungwengwe, Neziswa
- Date: 2021-04
- Subjects: Activity-based costing , Cost accounting , Managerial accounting
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/51765 , vital:43370
- Description: The primary research objective of this case study was to understand the effectiveness of cost containment measures implemented by all departments at Harry Gwala District Municipality. The case study also explored factors that may have contributed to the implementation of cost containment measures to ensure that the municipality spends funds on essential items and avoids unauthorised expenditure. A case study with fourteen (14) participants was chosen in order to focus on a particular area that the researcher could easily monitor. The researcher mixed qualitative and quantitative research designs to maintain the strengths and improve the weaknesses in both designs. Audited Annual Financial Statements and approved budgets were analysed to assess the effectiveness of cost containment measures. The study found that while employees were aware of their roles and responsibilities, it is safe to say that they did not follow procedures to ensure that costs were maintained. The results of the study showed that the Municipal Public Accounts Committee (MPAC) had no financial background. There was generally no change in the behaviour of employees as far as cost containment measures were concerned. The current repairs and maintenance budget was far below the norm of 8% of the carrying value of municipal assets and the municipality only budgeted between 2 – 3% per year for the assets with a carrying value of about R2.3 billion. , Thesis (MBA) -- Faculty of Business and Economic Sciences , Business Administration, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Lungwengwe, Neziswa
- Date: 2021-04
- Subjects: Activity-based costing , Cost accounting , Managerial accounting
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/51765 , vital:43370
- Description: The primary research objective of this case study was to understand the effectiveness of cost containment measures implemented by all departments at Harry Gwala District Municipality. The case study also explored factors that may have contributed to the implementation of cost containment measures to ensure that the municipality spends funds on essential items and avoids unauthorised expenditure. A case study with fourteen (14) participants was chosen in order to focus on a particular area that the researcher could easily monitor. The researcher mixed qualitative and quantitative research designs to maintain the strengths and improve the weaknesses in both designs. Audited Annual Financial Statements and approved budgets were analysed to assess the effectiveness of cost containment measures. The study found that while employees were aware of their roles and responsibilities, it is safe to say that they did not follow procedures to ensure that costs were maintained. The results of the study showed that the Municipal Public Accounts Committee (MPAC) had no financial background. There was generally no change in the behaviour of employees as far as cost containment measures were concerned. The current repairs and maintenance budget was far below the norm of 8% of the carrying value of municipal assets and the municipality only budgeted between 2 – 3% per year for the assets with a carrying value of about R2.3 billion. , Thesis (MBA) -- Faculty of Business and Economic Sciences , Business Administration, 2021
- Full Text:
- Date Issued: 2021-04
Selection for improved virulence of Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV) to False Codling Moth, Thaumatotibia leucotreta, by serial passage through a heterologous host
- Authors: Iita, Petrus Paulus
- Date: 2021-04
- Subjects: Cryptophlebia leucotreta -- Biological control , Biological pest control agents , Citrus -- Diseases and pests , Baculoviruses , Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV)
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178180 , vital:42918
- Description: The false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is endemic to southern Africa, and strongly associated with citrus. As South African citrus production is mainly for export to foreign markets, the market access risk due to the phytosanitary status of this pest is considerable and its control is therefore imperative. Various control measures as part of a rigorous integrated pest management (IPM) programme targeted against T. leucotreta have been effective at suppressing the pest in citrus, but there is still a growing need for continued improvement of the programme and augmentation of the available control options. Of these control options, biological control, particularly the use of Cryptophlebia leucotreta granulovirus (CrleGV-SA), is a key component of IPM in citrus orchards and it has been very successful at reducing T. leucotreta populations in the field for almost two decades. There is however, a growing need for more baculovirus variants with an improved virulence against T. leucotreta for a more efficient pest management system. The newly identified insect virus, Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV) offers a unique opportunity for an additional biopesticide in IPM for control of T. leucotreta in the field. This study aimed to conduct serial passaging of CrpeNPV through a heterologous host, T. leucotreta, in order to determine the potential for improved virulence or speed of kill against it. In order to select for a variant of CrpeNPV with improved virulence against T. leucotreta, a high dose (LC90) of the virus OBs was used to perform 12 serial passages through T. leucotreta larvae in surface-dose bioassays. Whole genome sequencing and analysis of the passaged virus, along with restriction endonuclease profiling in silico was performed to determine if the genetic identity of the virus had changed during serial passage, in relation to the original virus. These analyses indicated that the dominant genotype of CrpeNPV was maintained following 12 serial passages through the heterologous host. The biological activity of the passaged virus, along with the original virus was evaluated against neonate T. leucotreta in surface-dose bioassays and compared. Results from dose-response bioassays showed that the virulence of CrpeNPV did not improve after 12 serial passages. The LC50 values of the passaged virus and the original virus were estimated at 1.96 × 104 and 1.58 × 104 OBs/ml, respectively, whereas the LC90 values were estimated at 3.46 × 104 OBs/ml for the passaged virus and 3.68 × 104 for the original virus. Similarly, the results from time-response bioassays showed that the speed of kill of CrpeNPV did not improve after 12 serial passages. The LT50 values of the passaged virus and the original virus were 88.44 hours (3 days and 16 hours) and 83.74 hours (3 days and 12 hours), respectively, whereas the LT90 values were 115 hours (4 days 19 hours) for the passaged virus and 102 hours (4 days 6 hours) for the original virus. The virulence and speed of kill of the passaged virus decreased significantly, in relation to the original virus. When the full genome of the passaged virus was sequenced and analysed, only a few SNPs were detected in the viral genome, in comparison to the original virus. No detectable difference in REN digestion patterns were observed following REN analysis of gDNA of the passaged virus with several restriction enzymes in silico. The results for this study suggest that CrpeNPV may already be optimally suited to the heterologous host as it persists under these conditions without significant changes to the genome. These results have positive implications for the genetic integrity of CrpeNPV as a potential biocontrol agent in the field. This study is the first to report the virulence selection of CrpeNPV by serial passage through a heterologous host, and also the first to record bioassay data in terms of dose response (or lethal concentration) against T. leucotreta second instars. The data obtained have added to the knowledge about interactions between CrpeNPV and its heterologous host, and may be fundamental to continued investigation into the effect of serial passage on pathogenicity and genetic diversity of CrpeNPV. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Iita, Petrus Paulus
- Date: 2021-04
- Subjects: Cryptophlebia leucotreta -- Biological control , Biological pest control agents , Citrus -- Diseases and pests , Baculoviruses , Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV)
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178180 , vital:42918
- Description: The false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is endemic to southern Africa, and strongly associated with citrus. As South African citrus production is mainly for export to foreign markets, the market access risk due to the phytosanitary status of this pest is considerable and its control is therefore imperative. Various control measures as part of a rigorous integrated pest management (IPM) programme targeted against T. leucotreta have been effective at suppressing the pest in citrus, but there is still a growing need for continued improvement of the programme and augmentation of the available control options. Of these control options, biological control, particularly the use of Cryptophlebia leucotreta granulovirus (CrleGV-SA), is a key component of IPM in citrus orchards and it has been very successful at reducing T. leucotreta populations in the field for almost two decades. There is however, a growing need for more baculovirus variants with an improved virulence against T. leucotreta for a more efficient pest management system. The newly identified insect virus, Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV) offers a unique opportunity for an additional biopesticide in IPM for control of T. leucotreta in the field. This study aimed to conduct serial passaging of CrpeNPV through a heterologous host, T. leucotreta, in order to determine the potential for improved virulence or speed of kill against it. In order to select for a variant of CrpeNPV with improved virulence against T. leucotreta, a high dose (LC90) of the virus OBs was used to perform 12 serial passages through T. leucotreta larvae in surface-dose bioassays. Whole genome sequencing and analysis of the passaged virus, along with restriction endonuclease profiling in silico was performed to determine if the genetic identity of the virus had changed during serial passage, in relation to the original virus. These analyses indicated that the dominant genotype of CrpeNPV was maintained following 12 serial passages through the heterologous host. The biological activity of the passaged virus, along with the original virus was evaluated against neonate T. leucotreta in surface-dose bioassays and compared. Results from dose-response bioassays showed that the virulence of CrpeNPV did not improve after 12 serial passages. The LC50 values of the passaged virus and the original virus were estimated at 1.96 × 104 and 1.58 × 104 OBs/ml, respectively, whereas the LC90 values were estimated at 3.46 × 104 OBs/ml for the passaged virus and 3.68 × 104 for the original virus. Similarly, the results from time-response bioassays showed that the speed of kill of CrpeNPV did not improve after 12 serial passages. The LT50 values of the passaged virus and the original virus were 88.44 hours (3 days and 16 hours) and 83.74 hours (3 days and 12 hours), respectively, whereas the LT90 values were 115 hours (4 days 19 hours) for the passaged virus and 102 hours (4 days 6 hours) for the original virus. The virulence and speed of kill of the passaged virus decreased significantly, in relation to the original virus. When the full genome of the passaged virus was sequenced and analysed, only a few SNPs were detected in the viral genome, in comparison to the original virus. No detectable difference in REN digestion patterns were observed following REN analysis of gDNA of the passaged virus with several restriction enzymes in silico. The results for this study suggest that CrpeNPV may already be optimally suited to the heterologous host as it persists under these conditions without significant changes to the genome. These results have positive implications for the genetic integrity of CrpeNPV as a potential biocontrol agent in the field. This study is the first to report the virulence selection of CrpeNPV by serial passage through a heterologous host, and also the first to record bioassay data in terms of dose response (or lethal concentration) against T. leucotreta second instars. The data obtained have added to the knowledge about interactions between CrpeNPV and its heterologous host, and may be fundamental to continued investigation into the effect of serial passage on pathogenicity and genetic diversity of CrpeNPV. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
Comparative analysis of the known Hop1b and the novel Hop1a isoforms of the Hop gene
- Authors: Makhubu, Portia
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164311 , vital:41108 , doi:10.21504/10962/164311
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020
- Full Text:
- Date Issued: 2020
- Authors: Makhubu, Portia
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164311 , vital:41108 , doi:10.21504/10962/164311
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020
- Full Text:
- Date Issued: 2020
Softboi
- Authors: Mall, Shireen
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/164373 , vital:41113
- Description: Thesis (MA)--Rhodes University, Faculty of Humanities, School of Languages, 2020
- Full Text:
- Date Issued: 2020
- Authors: Mall, Shireen
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/164373 , vital:41113
- Description: Thesis (MA)--Rhodes University, Faculty of Humanities, School of Languages, 2020
- Full Text:
- Date Issued: 2020
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