Arshad Mather - Academia.edu (original) (raw)

Papers by Arshad Mather

SNAMA is the Drosophila melanogaster homologue of a group of proteins that are known to bind p53 ... more SNAMA is the Drosophila melanogaster homologue of a group of proteins that are known to bind p53 and the retinoblastoma protein (Rb). This multi domain protein consists of a conserved N-terminal domain called Domain With No Name (DWNN), a zinc finger, a cysteine rich RING finger-like domain, a probable p53 binding region, and a glutamic acid-rich and lysine-rich region. These associated domains indicate that SNAMA plays an important regulatory role in the cell and may function in RNA processing and in apoptosis. The DWNN domain was first identified in Cytotoxic T-cell resistant Chinese hamster ovary (CHO) cells using promoter trap mutagenesis to screen for genes involved in apoptosis. Subsequently, this domain was identified in other eukaryotic organisms including animals and plants. The SNAMA transcriptional unit consists of 9 exons and 8 introns that code for a 1231 amino acid protein with the 76 residue N-terminal DWNN domain. The DWNN domain has a 23.5% sequence identity to the ubiquitin protein and a predicted folded structure similar to ubiquitin. Western blots identified multiple bands indicative of ubiquitin tagged proteins. Taken together this suggests a role in the ubiquitin pathway either as an ubiquitin domain protein or the DWNN domain of SNAMA tagging other proteins. The cysteine rich RING finger-like domain has a histidine to serine substitution at the fourth position of the putative RING finger and represents a iv distinct class of RING finger-like proteins that could have ubiquitin ligase activity. Northern blot analysis identified a single 4.6 kbp transcript expressed abundantly throughout development early in embryogenesis but reduced in older embryos and in adult male and females. SNAMA probably interacts with Dmp53 as a suppressor of apoptosis or a negative regulator of an activator of apoptosis. It is a vital gene required for development, as the mutant P-element insertion line in which the Pelement is inserted in the first intron of SNAMA is lethal when homozygous. Acridine orange staining of these mutant flies showed a direct correlation between the presence of SNAMA and apoptosis. An increase in the levels of apoptosis occurred in embryos with relatively low levels of SNAMA expression. The mode of this action is either direct, or via other proteins that are involved in the apoptotic pathway. v This thesis is dedicated to my daughter Maseeha Mather. "Every day you may make progress. Every step may be fruitful. Yet there will stretch out before you an ever-lengthening, ever-ascending, ever-improving path. You know you will never get to the end of the journey. But this, so far from discouraging, only adds to the joy and glory of the climb." Sir Winston Churchill vi ACKNOWLEDGEMENTS My supervisor, Dr Monde Ntwasa for all his guidance, encouragement, and enthusiasm throughout my studies. My wife, Safiyya, for her constant encouragement and understanding over the many years. She has been patient and supportive of all my decisions. I would also like to thank my parents for their support and encouragement.

A better understanding of the basis of protective immunity and immunopathologic reactions associa... more A better understanding of the basis of protective immunity and immunopathologic reactions associated with contagious bovine pleuropneumonia (CBPP), caused by Mycoplasma mycoides subsp. mycoides small colony (MmmSC), is needed to develop better vaccines. Here we report on the characterization of T-cell memory responses associated with protective immunity in cattle and their use thereof to identify immuno-active proteins of MmmSC. Both effector memory (em) and central memory (cm)-like MmmSC specific CD4+ T cells were present ex vivo and capable of proliferation and IFN-γ production upon restimulation in vitro with inactivated MmmSC. It has been shown in mice and humans that priming of T(cm) is required for long-lived protective immunity, which is also an essential requirement of any improved vaccine against CBPP. Pre-sensitized T-cells were used to screen recombinant proteins of MmmSC produced as his-tagged proteins and purified by chromatography. Three of them were found to trigger the proliferation of both CD4+ T(em) and T(cm) and induce the production of IFN-γ: lipoprotein A (LppA), a glucose-specific component of the PTS system (ptsG) and to a lesser extent a substrate-binding component of the ABC transporter (ABC). In contrast, although lppQ had no effect on its own, it strongly inhibited the proliferation of CD4 in response to MmmSC by a mechanism apparently independent of direct cytotoxicity. In conclusion, the T-cell reagents and methodology described in this study will help identify immuno-protective antigens of MmmSC that have potential for the development of a subunit vaccine against CBPP. In addition, these cellular tools can also be used to screen for immuno-inhibitory proteins whose corresponding genes could be targets for deletion/inactivation in the aim of developing improved attenuated vaccines.

Frontiers in Veterinary Science, 2020

Lumpy skin disease and Rift Valley fever are two high-priority livestock diseases which have the ... more Lumpy skin disease and Rift Valley fever are two high-priority livestock diseases which have the potential to spread into previously free regions through animal movement and/or vectors, as well as intentional release by bioterrorists. Since the distribution range of both diseases is similar in Africa, it makes sense to use a bivalent vaccine to control them. This may lead to the more consistent and sustainable use of vaccination against Rift Valley fever through a more cost-effective vaccine. In this study, a recombinant lumpy skin disease virus was constructed in which the thymidine kinase gene was used as the insertion site for the Gn and Gc protective glycoprotein genes of Rift Valley fever virus using homologous recombination. Selection markers, the enhanced green fluorescent protein and Escherichia coli guanidine phosphoribosyl transferase (gpt), were used for selection of recombinant virus and in a manner enabling a second recombination event to occur upon removal of the gpt selection-pressure allowing the removal of both marker genes in the final product. This recombinant virus, LSD-RVF.mf, was selected to homogeneity, characterized and evaluated in cattle as a vaccine to show protection against both lumpy skin disease and Rift Valley fever in cattle. The results demonstrate that the LSD-RVF.mf is safe, immunogenic and can protect cattle against both diseases.

Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression, 2005

We have characterized SNAMA a hitherto uncharacterized Drosophila protein that appears to play a ... more We have characterized SNAMA a hitherto uncharacterized Drosophila protein that appears to play a role in apoptosis. SNAMA (something that sticks like glue) is a 1231 amino acid protein with a conserved 76 residue N-terminal domain called Domain With No Name (DWNN). The DWNN domain was first identified in cytotoxic T Cell-resistant CHO cells using promoter trap mutagenesis to screen for genes involved in apoptosis. Subsequently, this domain was identified in other eukaryotic organisms including animals and plants. The SNAMA transcript is abundant early in embryogenesis but reduced in older embryos and in adult males and females. Human and mouse homologues of SNAMA are known to bind to p53 and to the retinoblastoma protein (Rb) suggesting a role in transcriptional regulation and cell cycle control. We took advantage of a P-element insertion line in which the P-element is inserted in the first intron, to investigate the biological function of the gene. These mutants are lethal when homozygous. Apoptosis appears early during embryogenesis and is observed virtually throughout the gastrula. The DWNN domain has a ubiquitin-like fold and may interact with a subset of cellular proteins. There is also a conserved RING finger-like motif along the sequence of SNAMA following a C2HC zinc finger.

Additional file 4. ODs returned after testing sera from naïve group and CBPP-infected cattle. The... more Additional file 4. ODs returned after testing sera from naïve group and CBPP-infected cattle. The ODs were used to draw the box and scatter plots.

Additional file 5. ODs used to calculate the sensitivity and specificity of the naïve group and C... more Additional file 5. ODs used to calculate the sensitivity and specificity of the naïve group and CBPP-infected cattle. The ODs were used to determine the sensitivity and specificity of Mmm non-vaccine antigens.

Additional file 3. ODs returned after testing sera from the control group and subunit-vaccinated ... more Additional file 3. ODs returned after testing sera from the control group and subunit-vaccinated cattle. The ODs were used to draw box and scatter plots, and determine the sensitivity and specificity of Mmm vaccine antigens.

Additional file 1. A comparison of the performance of vaccine and non-vaccine antigens. The SPSS ... more Additional file 1. A comparison of the performance of vaccine and non-vaccine antigens. The SPSS was used to compare the performance of vaccine and non-vaccine antigens on sera from the control/naïve group, CBPP-infected, and subunit-vaccinated cattle.

Additional file 2. A comparison of the non-vaccine antigens on CBPP clinical stages. The SPSS was... more Additional file 2. A comparison of the non-vaccine antigens on CBPP clinical stages. The SPSS was used to compare the performance of non-vaccine antigens on sera (collected at different clinical stages) from the naïve group and CBPP-infected cattle.

Peste des petits ruminants (PPR) is a viral disease which primarily affects small ruminants, caus... more Peste des petits ruminants (PPR) is a viral disease which primarily affects small ruminants, causing significant economic losses for the livestock industry in developing countries. It is endemic in Saharan and sub-Saharan Africa, the Middle East and the Indian sub-continent. The primary hosts for peste des petits ruminants virus (PPRV) are goats and sheep; however recent models studying the pathology, disease progression and viremia of PPRV have focused primarily on goat models. This study evaluates the tissue tropism and pathogenesis of PPR following experimental infection of sheep and goats using a quantitative time-course study. Upon infection with a virulent strain of PPRV, both sheep and goats developed clinical signs and lesions typical of PPR, although sheep displayed milder clinical disease compared to goats. Tissue tropism of PPRV was evaluated by real-time RT-PCR and immunohistochemistry. Lymph nodes, lymphoid tissue and digestive tract organs were the predominant sites of...

Student Number : 9105022E - PhD thesis - School of Molecular and Cell Biology - Faculty of Science

Antiviral Research, 2015

Sheep and goat pox continue to be important livestock diseases that pose a major threat to the li... more Sheep and goat pox continue to be important livestock diseases that pose a major threat to the livestock industry in many regions in Africa and Asia. Currently, several live attenuated vaccines are available and used in endemic countries to control these diseases. One of these is a partially attenuated strain of lumpy skin disease virus (LSDV), KS-1, which provides cross-protection against both sheep pox and goat pox. However, when used in highly stressed dairy cattle to protect against lumpy skin disease (LSD) the vaccine can cause clinical disease. In order to develop safer vaccines effective against all three diseases, a pathogenic strain of LSDV (Warmbaths [WB], South Africa) was attenuated by removing a putative virulence factor gene (IL-10-like) using gene knockout (KO) technology. This construct (LSDV WB005KO) was then evaluated as a vaccine for sheep and goats against virulent capripoxvirus challenge. Sheep and goats were vaccinated with the construct and the animals were observed for 21days. The vaccine appeared to be safe, and did not cause disease, although it induced minor inflammation at the injection site similar to that caused by other attenuated sheep and goat pox vaccines. In addition, no virus replication was detected in blood, oral or nasal swabs using real-time PCR following vaccination and low levels of neutralising antibodies were detected in both sheep and goats. Leukocytes isolated from vaccinated animals following vaccination elicited capripoxvirus-specific IFN-γ secretion, suggesting that immunity was also T-cell mediated. Following challenge with virulent capripoxvirus, vaccinated sheep and goats were found to be completely protected and exhibited no clinical disease. Furthermore, real-time PCR of blood samples at various time points suggested that viremia was absent in both groups of vaccinated animals, as opposed to capripoxvirus-related clinical disease and viremia observed in the unvaccinated animals. These findings suggest that this novel knockout strain of LSDV has potential as a vaccine to protect livestock against sheep pox and goat pox.

PLoS ONE, 2014

Peste des petits ruminants (PPR) is a viral disease which primarily affects small ruminants, caus... more Peste des petits ruminants (PPR) is a viral disease which primarily affects small ruminants, causing significant economic losses for the livestock industry in developing countries. It is endemic in Saharan and sub-Saharan Africa, the Middle East and the Indian sub-continent. The primary hosts for peste des petits ruminants virus (PPRV) are goats and sheep; however recent models studying the pathology, disease progression and viremia of PPRV have focused primarily on goat models. This study evaluates the tissue tropism and pathogenesis of PPR following experimental infection of sheep and goats using a quantitative time-course study. Upon infection with a virulent strain of PPRV, both sheep and goats developed clinical signs and lesions typical of PPR, although sheep displayed milder clinical disease compared to goats. Tissue tropism of PPRV was evaluated by real-time RT-PCR and immunohistochemistry. Lymph nodes, lymphoid tissue and digestive tract organs were the predominant sites of virus replication. The results presented in this study provide models for the comparative evaluation of PPRV pathogenesis and tissue tropism in both sheep and goats. These models are suitable for the establishment of experimental parameters necessary for the evaluation of vaccines, as well as further studies into PPRV-host interactions.

Antiviral Research, 2013

Five different viral diseases of livestock, lumpy skin disease (LSD), sheep pox (SPP), goat pox (... more Five different viral diseases of livestock, lumpy skin disease (LSD), sheep pox (SPP), goat pox (GTP), Rift Valley fever (RVF) and peste des petits ruminants (PPR), circulate in the same regions of Africa, imposing a major burden on economic activity and public health. While commercial vaccines against these viruses are available, the cost of implementing regular vaccination regimens against multiple diseases is prohibitive for most African farmers. A single, affordable multivalent vaccine that simultaneously protects against all 5 diseases would therefore be of significant benefit to the livestock sector in Africa. It could also serve as a platform for the development of new vaccines of significance to other developing countries around the world. In this paper, we present an overview of the economic importance of livestock in Africa, the pathogens responsible for RVF, PPR, SPP, GTP and LSD and the vaccination strategies currently used to combat them. We then review experience with the development of attenuated capripoxviruses as vaccines against LSD, SPP and GTP and of recombinant capripoxvirus-vectored vaccines against RVF and PPR. We conclude the article by presenting the rationale for a single, multivalent capripoxvirus-vectored vaccine that would protect against all 5 diseases of livestock, and describe the approach being taken by a consortium of Canadian and South African researchers to develop such a vaccine.

Clinical and Vaccine Immunology, 2010

Genes of the Mycoplasma mycoides subsp. mycoides small colony biotype (MmmSC) coding for proteins... more Genes of the Mycoplasma mycoides subsp. mycoides small colony biotype (MmmSC) coding for proteins capable of eliciting protective T-cell memory responses have potential for incorporation into a recombinant subunit vaccine against contagious bovine pleuropneumonia (CBPP). Here we used lymphocytes from cattle that had completely recovered from infection to screen products of MmmSC genes for recognition by CD4+ effector memory (Tem) and central memory (Tcm) T lymphocytes. Six MmmSC genes (abc, gapN, glpO, lppA, lppB, and ptsG) were expressed as histidine-tagged recombinant polypeptides, or synthetic overlapping peptides, before inclusion in proliferation and gamma interferon (IFN-γ) assays. Only two MmmSC antigens, LppA and PtsG, consistently induced recall proliferation from immune CD4+ T cells and IFN-γ production in all animals tested. Moreover, LppA and PtsG were shown to possess epitopes recognized by both short-lived CD4+ Tem and long-lived CD4+ Tcm cells.

SNAMA is the Drosophila melanogaster homologue of a group of proteins that are known to bind p53 ... more SNAMA is the Drosophila melanogaster homologue of a group of proteins that are known to bind p53 and the retinoblastoma protein (Rb). This multi domain protein consists of a conserved N-terminal domain called Domain With No Name (DWNN), a zinc finger, a cysteine rich RING finger-like domain, a probable p53 binding region, and a glutamic acid-rich and lysine-rich region. These associated domains indicate that SNAMA plays an important regulatory role in the cell and may function in RNA processing and in apoptosis. The DWNN domain was first identified in Cytotoxic T-cell resistant Chinese hamster ovary (CHO) cells using promoter trap mutagenesis to screen for genes involved in apoptosis. Subsequently, this domain was identified in other eukaryotic organisms including animals and plants. The SNAMA transcriptional unit consists of 9 exons and 8 introns that code for a 1231 amino acid protein with the 76 residue N-terminal DWNN domain. The DWNN domain has a 23.5% sequence identity to the ubiquitin protein and a predicted folded structure similar to ubiquitin. Western blots identified multiple bands indicative of ubiquitin tagged proteins. Taken together this suggests a role in the ubiquitin pathway either as an ubiquitin domain protein or the DWNN domain of SNAMA tagging other proteins. The cysteine rich RING finger-like domain has a histidine to serine substitution at the fourth position of the putative RING finger and represents a iv distinct class of RING finger-like proteins that could have ubiquitin ligase activity. Northern blot analysis identified a single 4.6 kbp transcript expressed abundantly throughout development early in embryogenesis but reduced in older embryos and in adult male and females. SNAMA probably interacts with Dmp53 as a suppressor of apoptosis or a negative regulator of an activator of apoptosis. It is a vital gene required for development, as the mutant P-element insertion line in which the Pelement is inserted in the first intron of SNAMA is lethal when homozygous. Acridine orange staining of these mutant flies showed a direct correlation between the presence of SNAMA and apoptosis. An increase in the levels of apoptosis occurred in embryos with relatively low levels of SNAMA expression. The mode of this action is either direct, or via other proteins that are involved in the apoptotic pathway. v This thesis is dedicated to my daughter Maseeha Mather. "Every day you may make progress. Every step may be fruitful. Yet there will stretch out before you an ever-lengthening, ever-ascending, ever-improving path. You know you will never get to the end of the journey. But this, so far from discouraging, only adds to the joy and glory of the climb." Sir Winston Churchill vi ACKNOWLEDGEMENTS My supervisor, Dr Monde Ntwasa for all his guidance, encouragement, and enthusiasm throughout my studies. My wife, Safiyya, for her constant encouragement and understanding over the many years. She has been patient and supportive of all my decisions. I would also like to thank my parents for their support and encouragement.

A better understanding of the basis of protective immunity and immunopathologic reactions associa... more A better understanding of the basis of protective immunity and immunopathologic reactions associated with contagious bovine pleuropneumonia (CBPP), caused by Mycoplasma mycoides subsp. mycoides small colony (MmmSC), is needed to develop better vaccines. Here we report on the characterization of T-cell memory responses associated with protective immunity in cattle and their use thereof to identify immuno-active proteins of MmmSC. Both effector memory (em) and central memory (cm)-like MmmSC specific CD4+ T cells were present ex vivo and capable of proliferation and IFN-γ production upon restimulation in vitro with inactivated MmmSC. It has been shown in mice and humans that priming of T(cm) is required for long-lived protective immunity, which is also an essential requirement of any improved vaccine against CBPP. Pre-sensitized T-cells were used to screen recombinant proteins of MmmSC produced as his-tagged proteins and purified by chromatography. Three of them were found to trigger the proliferation of both CD4+ T(em) and T(cm) and induce the production of IFN-γ: lipoprotein A (LppA), a glucose-specific component of the PTS system (ptsG) and to a lesser extent a substrate-binding component of the ABC transporter (ABC). In contrast, although lppQ had no effect on its own, it strongly inhibited the proliferation of CD4 in response to MmmSC by a mechanism apparently independent of direct cytotoxicity. In conclusion, the T-cell reagents and methodology described in this study will help identify immuno-protective antigens of MmmSC that have potential for the development of a subunit vaccine against CBPP. In addition, these cellular tools can also be used to screen for immuno-inhibitory proteins whose corresponding genes could be targets for deletion/inactivation in the aim of developing improved attenuated vaccines.

Frontiers in Veterinary Science, 2020

Lumpy skin disease and Rift Valley fever are two high-priority livestock diseases which have the ... more Lumpy skin disease and Rift Valley fever are two high-priority livestock diseases which have the potential to spread into previously free regions through animal movement and/or vectors, as well as intentional release by bioterrorists. Since the distribution range of both diseases is similar in Africa, it makes sense to use a bivalent vaccine to control them. This may lead to the more consistent and sustainable use of vaccination against Rift Valley fever through a more cost-effective vaccine. In this study, a recombinant lumpy skin disease virus was constructed in which the thymidine kinase gene was used as the insertion site for the Gn and Gc protective glycoprotein genes of Rift Valley fever virus using homologous recombination. Selection markers, the enhanced green fluorescent protein and Escherichia coli guanidine phosphoribosyl transferase (gpt), were used for selection of recombinant virus and in a manner enabling a second recombination event to occur upon removal of the gpt selection-pressure allowing the removal of both marker genes in the final product. This recombinant virus, LSD-RVF.mf, was selected to homogeneity, characterized and evaluated in cattle as a vaccine to show protection against both lumpy skin disease and Rift Valley fever in cattle. The results demonstrate that the LSD-RVF.mf is safe, immunogenic and can protect cattle against both diseases.

Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression, 2005

We have characterized SNAMA a hitherto uncharacterized Drosophila protein that appears to play a ... more We have characterized SNAMA a hitherto uncharacterized Drosophila protein that appears to play a role in apoptosis. SNAMA (something that sticks like glue) is a 1231 amino acid protein with a conserved 76 residue N-terminal domain called Domain With No Name (DWNN). The DWNN domain was first identified in cytotoxic T Cell-resistant CHO cells using promoter trap mutagenesis to screen for genes involved in apoptosis. Subsequently, this domain was identified in other eukaryotic organisms including animals and plants. The SNAMA transcript is abundant early in embryogenesis but reduced in older embryos and in adult males and females. Human and mouse homologues of SNAMA are known to bind to p53 and to the retinoblastoma protein (Rb) suggesting a role in transcriptional regulation and cell cycle control. We took advantage of a P-element insertion line in which the P-element is inserted in the first intron, to investigate the biological function of the gene. These mutants are lethal when homozygous. Apoptosis appears early during embryogenesis and is observed virtually throughout the gastrula. The DWNN domain has a ubiquitin-like fold and may interact with a subset of cellular proteins. There is also a conserved RING finger-like motif along the sequence of SNAMA following a C2HC zinc finger.

Additional file 4. ODs returned after testing sera from naïve group and CBPP-infected cattle. The... more Additional file 4. ODs returned after testing sera from naïve group and CBPP-infected cattle. The ODs were used to draw the box and scatter plots.

Additional file 5. ODs used to calculate the sensitivity and specificity of the naïve group and C... more Additional file 5. ODs used to calculate the sensitivity and specificity of the naïve group and CBPP-infected cattle. The ODs were used to determine the sensitivity and specificity of Mmm non-vaccine antigens.

Additional file 3. ODs returned after testing sera from the control group and subunit-vaccinated ... more Additional file 3. ODs returned after testing sera from the control group and subunit-vaccinated cattle. The ODs were used to draw box and scatter plots, and determine the sensitivity and specificity of Mmm vaccine antigens.

Additional file 1. A comparison of the performance of vaccine and non-vaccine antigens. The SPSS ... more Additional file 1. A comparison of the performance of vaccine and non-vaccine antigens. The SPSS was used to compare the performance of vaccine and non-vaccine antigens on sera from the control/naïve group, CBPP-infected, and subunit-vaccinated cattle.

Additional file 2. A comparison of the non-vaccine antigens on CBPP clinical stages. The SPSS was... more Additional file 2. A comparison of the non-vaccine antigens on CBPP clinical stages. The SPSS was used to compare the performance of non-vaccine antigens on sera (collected at different clinical stages) from the naïve group and CBPP-infected cattle.

Peste des petits ruminants (PPR) is a viral disease which primarily affects small ruminants, caus... more Peste des petits ruminants (PPR) is a viral disease which primarily affects small ruminants, causing significant economic losses for the livestock industry in developing countries. It is endemic in Saharan and sub-Saharan Africa, the Middle East and the Indian sub-continent. The primary hosts for peste des petits ruminants virus (PPRV) are goats and sheep; however recent models studying the pathology, disease progression and viremia of PPRV have focused primarily on goat models. This study evaluates the tissue tropism and pathogenesis of PPR following experimental infection of sheep and goats using a quantitative time-course study. Upon infection with a virulent strain of PPRV, both sheep and goats developed clinical signs and lesions typical of PPR, although sheep displayed milder clinical disease compared to goats. Tissue tropism of PPRV was evaluated by real-time RT-PCR and immunohistochemistry. Lymph nodes, lymphoid tissue and digestive tract organs were the predominant sites of...

Student Number : 9105022E - PhD thesis - School of Molecular and Cell Biology - Faculty of Science

Antiviral Research, 2015

Sheep and goat pox continue to be important livestock diseases that pose a major threat to the li... more Sheep and goat pox continue to be important livestock diseases that pose a major threat to the livestock industry in many regions in Africa and Asia. Currently, several live attenuated vaccines are available and used in endemic countries to control these diseases. One of these is a partially attenuated strain of lumpy skin disease virus (LSDV), KS-1, which provides cross-protection against both sheep pox and goat pox. However, when used in highly stressed dairy cattle to protect against lumpy skin disease (LSD) the vaccine can cause clinical disease. In order to develop safer vaccines effective against all three diseases, a pathogenic strain of LSDV (Warmbaths [WB], South Africa) was attenuated by removing a putative virulence factor gene (IL-10-like) using gene knockout (KO) technology. This construct (LSDV WB005KO) was then evaluated as a vaccine for sheep and goats against virulent capripoxvirus challenge. Sheep and goats were vaccinated with the construct and the animals were observed for 21days. The vaccine appeared to be safe, and did not cause disease, although it induced minor inflammation at the injection site similar to that caused by other attenuated sheep and goat pox vaccines. In addition, no virus replication was detected in blood, oral or nasal swabs using real-time PCR following vaccination and low levels of neutralising antibodies were detected in both sheep and goats. Leukocytes isolated from vaccinated animals following vaccination elicited capripoxvirus-specific IFN-γ secretion, suggesting that immunity was also T-cell mediated. Following challenge with virulent capripoxvirus, vaccinated sheep and goats were found to be completely protected and exhibited no clinical disease. Furthermore, real-time PCR of blood samples at various time points suggested that viremia was absent in both groups of vaccinated animals, as opposed to capripoxvirus-related clinical disease and viremia observed in the unvaccinated animals. These findings suggest that this novel knockout strain of LSDV has potential as a vaccine to protect livestock against sheep pox and goat pox.

PLoS ONE, 2014

Peste des petits ruminants (PPR) is a viral disease which primarily affects small ruminants, caus... more Peste des petits ruminants (PPR) is a viral disease which primarily affects small ruminants, causing significant economic losses for the livestock industry in developing countries. It is endemic in Saharan and sub-Saharan Africa, the Middle East and the Indian sub-continent. The primary hosts for peste des petits ruminants virus (PPRV) are goats and sheep; however recent models studying the pathology, disease progression and viremia of PPRV have focused primarily on goat models. This study evaluates the tissue tropism and pathogenesis of PPR following experimental infection of sheep and goats using a quantitative time-course study. Upon infection with a virulent strain of PPRV, both sheep and goats developed clinical signs and lesions typical of PPR, although sheep displayed milder clinical disease compared to goats. Tissue tropism of PPRV was evaluated by real-time RT-PCR and immunohistochemistry. Lymph nodes, lymphoid tissue and digestive tract organs were the predominant sites of virus replication. The results presented in this study provide models for the comparative evaluation of PPRV pathogenesis and tissue tropism in both sheep and goats. These models are suitable for the establishment of experimental parameters necessary for the evaluation of vaccines, as well as further studies into PPRV-host interactions.

Antiviral Research, 2013

Five different viral diseases of livestock, lumpy skin disease (LSD), sheep pox (SPP), goat pox (... more Five different viral diseases of livestock, lumpy skin disease (LSD), sheep pox (SPP), goat pox (GTP), Rift Valley fever (RVF) and peste des petits ruminants (PPR), circulate in the same regions of Africa, imposing a major burden on economic activity and public health. While commercial vaccines against these viruses are available, the cost of implementing regular vaccination regimens against multiple diseases is prohibitive for most African farmers. A single, affordable multivalent vaccine that simultaneously protects against all 5 diseases would therefore be of significant benefit to the livestock sector in Africa. It could also serve as a platform for the development of new vaccines of significance to other developing countries around the world. In this paper, we present an overview of the economic importance of livestock in Africa, the pathogens responsible for RVF, PPR, SPP, GTP and LSD and the vaccination strategies currently used to combat them. We then review experience with the development of attenuated capripoxviruses as vaccines against LSD, SPP and GTP and of recombinant capripoxvirus-vectored vaccines against RVF and PPR. We conclude the article by presenting the rationale for a single, multivalent capripoxvirus-vectored vaccine that would protect against all 5 diseases of livestock, and describe the approach being taken by a consortium of Canadian and South African researchers to develop such a vaccine.

Clinical and Vaccine Immunology, 2010

Genes of the Mycoplasma mycoides subsp. mycoides small colony biotype (MmmSC) coding for proteins... more Genes of the Mycoplasma mycoides subsp. mycoides small colony biotype (MmmSC) coding for proteins capable of eliciting protective T-cell memory responses have potential for incorporation into a recombinant subunit vaccine against contagious bovine pleuropneumonia (CBPP). Here we used lymphocytes from cattle that had completely recovered from infection to screen products of MmmSC genes for recognition by CD4+ effector memory (Tem) and central memory (Tcm) T lymphocytes. Six MmmSC genes (abc, gapN, glpO, lppA, lppB, and ptsG) were expressed as histidine-tagged recombinant polypeptides, or synthetic overlapping peptides, before inclusion in proliferation and gamma interferon (IFN-γ) assays. Only two MmmSC antigens, LppA and PtsG, consistently induced recall proliferation from immune CD4+ T cells and IFN-γ production in all animals tested. Moreover, LppA and PtsG were shown to possess epitopes recognized by both short-lived CD4+ Tem and long-lived CD4+ Tcm cells.