The Experts below are selected from a list of 60 Experts worldwide ranked by ideXlab platform
Mark P. Stevens - One of the best experts on this subject based on the ideXlab platform.
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Nature and consequences of interactions between Salmonella enterica serovar Dublin and host cells in cattle
Veterinary Research, 2019Co-Authors: Prerna Vohra, Christina Vrettou, Jayne C. Hope, John Hopkins, Mark P. StevensAbstract:AbstractSalmonella enterica is a veterinary and zoonotic pathogen of global importance. While murine and cell-based models of infection have provided considerable knowledge about the molecular basis of virulence of Salmonella, relatively little is known about salmonellosis in naturally-affected large animal hosts such as cattle, which are a reservoir of human salmonellosis. As in humans, Salmonella causes Bovine Disease ranging from self-limiting enteritis to systemic typhoid-like Disease and exerts significant economic and welfare costs. Understanding the nature and consequences of Salmonella interactions with Bovine cells will inform the design of effective vaccines and interventions to control animal and zoonotic infections. In calves challenged orally with S. Dublin expressing green fluorescent protein (GFP) we observed that the bacteria were predominantly extracellular in the distal ileal mucosa and within gut-associated lymph nodes 48 h post-infection. Intracellular bacteria, identified by flow cytometry using the GFP signal, were predominantly within MHCII+ macrophage-like cells. In contrast to observations from murine models, these S. Dublin-infected cells had elevated levels of MHCII and CD40 compared to both uninfected cells from the same tissue and cells from the cognate tissue of uninfected animals. Moreover, no gross changes of the architecture of infected lymph nodes were observed as was described previously in a mouse model. In order to further investigate Salmonella-macrophage interactions, net replication of S. enterica serovars that differ in virulence in cattle was measured in Bovine blood-derived macrophages by enumeration of gentamicin-protected bacteria and fluorescence dilution, but did not correlate with host-specificity.
William Weir - One of the best experts on this subject based on the ideXlab platform.
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identification and analysis of immunodominant antigens for elisa based detection of theileria annulata
PLOS ONE, 2016Co-Authors: Huseyin Bilgin Bilgic, Brian Shiels, Andrew Tait, Tulin Karagenc, Serkan Bakirci, Jane Kinnaird, Hasan Eren, William WeirAbstract:Tropical or Mediterranean theileriosis, caused by the protozoan parasite Theileria annulata, remains an economically important Bovine Disease in North Africa, Southern Europe, India, the Middle East and Asia. The Disease affects mainly exotic cattle and imposes serious constraints upon livestock production and breed improvement programmes. While microscopic and molecular methods exist which are capable of detecting T. annulata during acute infection, the identification of animals in the carrier state is more challenging. Serological tests, which detect antibodies that react against parasite-encoded antigens, should ideally have the potential to identify carrier animals with very high levels of sensitivity and specificity. However, assays developed to date have suffered from a lack of sensitivity and/or specificity and it is, therefore, necessary to identify novel parasite antigens, which can be developed for this purpose. In the present study, genes encoding predicted antigens were bioinformatically identified in the T. annulata genome. These proteins, together with a panel of previously described antigens, were assessed by western blot analysis for immunoreactivity, and this revealed that four novel candidates and five previously described antigens were recognised by immune Bovine serum. Using a combination of immunoprecipitation and mass spectrophotometric analysis, an immunodominant protein (encoded by TA15705) was identified as Ta9, a previously defined T cell antigen. Western blotting revealed another of the five proteins in the Ta9 family, TA15710, also to be an immunodominant protein. However, validation by Enzyme-Linked Immunosorbent Assay indicated that due to either allelic polymorphism or differential immune responses of individual hosts, none of the novel candidates can be considered ideal for routine detection of T. annulata-infected/carrier animals.
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population diversity and multiplicity of infection in theileria annulata
International Journal for Parasitology, 2011Co-Authors: William Weir, Martin Simuunza, Brian Shiels, Mohamed Aziz Darghouth, Suleyman Aypak, Nuran Aysul, Mohamed Gharbi, Tulin Karagenc, Andrew TaitAbstract:The tick-borne apicomplexan parasite Theileria annulata is endemic in many sub-tropical countries and causes the Bovine Disease tropical theileriosis. Although the parasite is known to be highly diverse, detailed information is lacking on the genetic structure of natural populations and levels of multiplicity of infection in the cattle host. With the widespread deployment of live attenuated vaccines and the emergence of drug-resistant parasites in the field, it is vital to appreciate the factors which shape genetic diversity of the parasite both within individual hosts and in the wider population. This study addresses these issues and represents an extensive genetic analysis of T. annulata populations in two endemic countries utilising a high-throughput adaptation of a micro- and mini-satellite genotyping system. Parasite material was collected from infected cattle in defined regions of Turkey and Tunisia to allow a variety of analyses to be conducted. All animals (n = 305) were found to harbour multiple parasite genotypes and only two isolates shared an identical predominant multi-locus profile. A modelling approach was used to demonstrate that host age, location and vaccination status play a measurable role in determining multiplicity of infection in an individual animal. Age was shown to positively correlate with multiplicity of infection and while positive vaccination status exerted a similar effect, it was shown to be due not simply to the presence of the immunising genotype. Importantly, no direct evidence was found for the immunising genotype spreading or recombining within the local parasite community. Genetic analysis confirmed the tentative conclusion of a previous study that the parasite population appears to be, in general, panmictic. Nevertheless, evidence supporting linkage disequilibrium and a departure from panmixia was uncovered in some localities and a number of explanations for these findings are advanced.
Prerna Vohra - One of the best experts on this subject based on the ideXlab platform.
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Nature and consequences of interactions between Salmonella enterica serovar Dublin and host cells in cattle
Veterinary Research, 2019Co-Authors: Prerna Vohra, Christina Vrettou, Jayne C. Hope, John Hopkins, Mark P. StevensAbstract:AbstractSalmonella enterica is a veterinary and zoonotic pathogen of global importance. While murine and cell-based models of infection have provided considerable knowledge about the molecular basis of virulence of Salmonella, relatively little is known about salmonellosis in naturally-affected large animal hosts such as cattle, which are a reservoir of human salmonellosis. As in humans, Salmonella causes Bovine Disease ranging from self-limiting enteritis to systemic typhoid-like Disease and exerts significant economic and welfare costs. Understanding the nature and consequences of Salmonella interactions with Bovine cells will inform the design of effective vaccines and interventions to control animal and zoonotic infections. In calves challenged orally with S. Dublin expressing green fluorescent protein (GFP) we observed that the bacteria were predominantly extracellular in the distal ileal mucosa and within gut-associated lymph nodes 48 h post-infection. Intracellular bacteria, identified by flow cytometry using the GFP signal, were predominantly within MHCII+ macrophage-like cells. In contrast to observations from murine models, these S. Dublin-infected cells had elevated levels of MHCII and CD40 compared to both uninfected cells from the same tissue and cells from the cognate tissue of uninfected animals. Moreover, no gross changes of the architecture of infected lymph nodes were observed as was described previously in a mouse model. In order to further investigate Salmonella-macrophage interactions, net replication of S. enterica serovars that differ in virulence in cattle was measured in Bovine blood-derived macrophages by enumeration of gentamicin-protected bacteria and fluorescence dilution, but did not correlate with host-specificity.
Andrew Tait - One of the best experts on this subject based on the ideXlab platform.
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identification and analysis of immunodominant antigens for elisa based detection of theileria annulata
PLOS ONE, 2016Co-Authors: Huseyin Bilgin Bilgic, Brian Shiels, Andrew Tait, Tulin Karagenc, Serkan Bakirci, Jane Kinnaird, Hasan Eren, William WeirAbstract:Tropical or Mediterranean theileriosis, caused by the protozoan parasite Theileria annulata, remains an economically important Bovine Disease in North Africa, Southern Europe, India, the Middle East and Asia. The Disease affects mainly exotic cattle and imposes serious constraints upon livestock production and breed improvement programmes. While microscopic and molecular methods exist which are capable of detecting T. annulata during acute infection, the identification of animals in the carrier state is more challenging. Serological tests, which detect antibodies that react against parasite-encoded antigens, should ideally have the potential to identify carrier animals with very high levels of sensitivity and specificity. However, assays developed to date have suffered from a lack of sensitivity and/or specificity and it is, therefore, necessary to identify novel parasite antigens, which can be developed for this purpose. In the present study, genes encoding predicted antigens were bioinformatically identified in the T. annulata genome. These proteins, together with a panel of previously described antigens, were assessed by western blot analysis for immunoreactivity, and this revealed that four novel candidates and five previously described antigens were recognised by immune Bovine serum. Using a combination of immunoprecipitation and mass spectrophotometric analysis, an immunodominant protein (encoded by TA15705) was identified as Ta9, a previously defined T cell antigen. Western blotting revealed another of the five proteins in the Ta9 family, TA15710, also to be an immunodominant protein. However, validation by Enzyme-Linked Immunosorbent Assay indicated that due to either allelic polymorphism or differential immune responses of individual hosts, none of the novel candidates can be considered ideal for routine detection of T. annulata-infected/carrier animals.
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population diversity and multiplicity of infection in theileria annulata
International Journal for Parasitology, 2011Co-Authors: William Weir, Martin Simuunza, Brian Shiels, Mohamed Aziz Darghouth, Suleyman Aypak, Nuran Aysul, Mohamed Gharbi, Tulin Karagenc, Andrew TaitAbstract:The tick-borne apicomplexan parasite Theileria annulata is endemic in many sub-tropical countries and causes the Bovine Disease tropical theileriosis. Although the parasite is known to be highly diverse, detailed information is lacking on the genetic structure of natural populations and levels of multiplicity of infection in the cattle host. With the widespread deployment of live attenuated vaccines and the emergence of drug-resistant parasites in the field, it is vital to appreciate the factors which shape genetic diversity of the parasite both within individual hosts and in the wider population. This study addresses these issues and represents an extensive genetic analysis of T. annulata populations in two endemic countries utilising a high-throughput adaptation of a micro- and mini-satellite genotyping system. Parasite material was collected from infected cattle in defined regions of Turkey and Tunisia to allow a variety of analyses to be conducted. All animals (n = 305) were found to harbour multiple parasite genotypes and only two isolates shared an identical predominant multi-locus profile. A modelling approach was used to demonstrate that host age, location and vaccination status play a measurable role in determining multiplicity of infection in an individual animal. Age was shown to positively correlate with multiplicity of infection and while positive vaccination status exerted a similar effect, it was shown to be due not simply to the presence of the immunising genotype. Importantly, no direct evidence was found for the immunising genotype spreading or recombining within the local parasite community. Genetic analysis confirmed the tentative conclusion of a previous study that the parasite population appears to be, in general, panmictic. Nevertheless, evidence supporting linkage disequilibrium and a departure from panmixia was uncovered in some localities and a number of explanations for these findings are advanced.
Christina Vrettou - One of the best experts on this subject based on the ideXlab platform.
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Nature and consequences of interactions between Salmonella enterica serovar Dublin and host cells in cattle
Veterinary Research, 2019Co-Authors: Prerna Vohra, Christina Vrettou, Jayne C. Hope, John Hopkins, Mark P. StevensAbstract:AbstractSalmonella enterica is a veterinary and zoonotic pathogen of global importance. While murine and cell-based models of infection have provided considerable knowledge about the molecular basis of virulence of Salmonella, relatively little is known about salmonellosis in naturally-affected large animal hosts such as cattle, which are a reservoir of human salmonellosis. As in humans, Salmonella causes Bovine Disease ranging from self-limiting enteritis to systemic typhoid-like Disease and exerts significant economic and welfare costs. Understanding the nature and consequences of Salmonella interactions with Bovine cells will inform the design of effective vaccines and interventions to control animal and zoonotic infections. In calves challenged orally with S. Dublin expressing green fluorescent protein (GFP) we observed that the bacteria were predominantly extracellular in the distal ileal mucosa and within gut-associated lymph nodes 48 h post-infection. Intracellular bacteria, identified by flow cytometry using the GFP signal, were predominantly within MHCII+ macrophage-like cells. In contrast to observations from murine models, these S. Dublin-infected cells had elevated levels of MHCII and CD40 compared to both uninfected cells from the same tissue and cells from the cognate tissue of uninfected animals. Moreover, no gross changes of the architecture of infected lymph nodes were observed as was described previously in a mouse model. In order to further investigate Salmonella-macrophage interactions, net replication of S. enterica serovars that differ in virulence in cattle was measured in Bovine blood-derived macrophages by enumeration of gentamicin-protected bacteria and fluorescence dilution, but did not correlate with host-specificity.