Publications by authors named "Thomas Tzelos"

Autologous administration of attenuated Theileria parva-infected cells induces immunity to T. parva in cattle. The mechanism of attenuation, however, is largely unknown.

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Domestic sheep (Ovis aries) have been an important component of livestock agricultural production for thousands of years. Preserving genetic diversity within livestock populations maintains a capacity to respond to changing environments and rapidly evolving pathogens. MHC genetic diversity can influence immune functionality at individual and population levels.

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Early pregnancy diagnosis is key to maximise productivity of dairy herds. We previously showed that an increase in the levels of miR-26 could be detected as soon as day 8 of pregnancy in heifers. The aims of this study were to determine whether 1) plasma miR-26 levels would be distinctly elevated, retrospectively, early after artificial insemination in lactating cows with successful compared to failed pregnancies, 2) the early increase in miRNA levels in cows with successful pregnancy could be accounted for by changes in miRNA expression in white blood cells (WBCs), presumably induced by the effects of embryo-derived interferon tau (IFNt), and 3) plasma miRNA levels may provide a reliable early predictor of pregnancy that could be used at a herd level.

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The Major Histocompatibility Complex (MHC) genes play a key role in a number of biological processes, most notably in immunological responses. The MHCI and MHCII genes incorporate a complex set of highly polymorphic and polygenic series of genes, which, due to the technical limitations of previously available technologies, have only been partially characterized in non-model but economically important species such as the horse. The advent of high-throughput sequencing platforms has provided new opportunities to develop methods to generate high-resolution sequencing data on a large scale and apply them to the analysis of complex gene sets such as the MHC.

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Article Synopsis
  • The study investigates the role of classical MHC class I and II molecules in CD8+ and CD4+ T-cell responses, focusing on the genetic diversity of cattle's immune system in low-and-middle income countries (LMICs), particularly Zambia.
  • It develops a high-throughput MiSeq-based platform to analyze the BoLA-DQA, BoLA-DQB, BoLA-I, and BoLA-DRB genes in approximately 800 indigenous cattle from three breeds (Angoni, Barotse, Tonga).
  • The findings reveal significant diversity in MHC genotypes within these cattle populations, highlighting potential applications in vaccine development and further research on immune responses in livestock.
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The major histocompatibility complex (MHC) contains many genes that play key roles in initiating and regulating immune responses. This includes the polymorphic MHCI and MHCII genes that present epitopes to CD8+ and CD4+ T-cells, respectively. Consequently, the characterisation of the repertoire of MHC genes is an important component of improving our understanding of the genetic variation that determines the outcomes of immune responses.

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Dairy cow farming plays an important role in the UK and worldwide economies. Significant challenges are currently being faced regarding sustainability of the dairy industry. Dairy cow subfertility remains an important issue limiting herd productivity, resulting in annual losses of hundreds of millions of pounds in the UK alone.

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  • Bovine tuberculosis (bTB) is a chronic disease in cattle that may be influenced by genetic factors, particularly the NRAMP1 gene, which plays a role in immune response.
  • A study identified five single nucleotide polymorphisms (SNPs) in the NRAMP1 gene across different cattle breeds, with SNP4 (c.1066C>G) being common to all breeds and linked to NRAMP1 expression.
  • Results showed that cattle with the alternative G allele at SNP4 had higher NRAMP1 expression, suggesting they may have increased resistance to bTB due to enhanced immune responses in their macrophages.
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Cyathostomins are ubiquitous parasitic nematodes of horses. These worms spend substantial periods as intestinal wall stage encysted larvae, which can comprise up to 90% of the total burden. Several million larvae have been reported in individuals.

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Interval treatment control programmes used widely in equine helminth control have favoured the development of anthelmintic resistance worldwide. Best practice guidelines have been designed to address resistance and include the requirement for improved pasture hygiene to break helminth transmission cycles, along with anthelmintic application informed by the results of diagnostic tests to reduce selection pressure for resistance. Using an online questionnaire, this study examined uptake of measures recommended in these guidelines by UK horse owners.

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Article Synopsis
  • * The cluster of miRNAs can be detected in sheep infected with H. contortus, suggesting their release into host tissues, and the worms secrete extracellular vesicles containing these miRNAs.
  • * Analysis of the small RNA content shows that while some miRNAs are found in vesicles, others are more prevalent in a non-vesicular form, with insights pointing to the gut as the source of miRNAs in L4 stage larvae, highlighting
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Parasitic nematodes, particularly cyathostomins, are ubiquitous in grazing horses world-wide. Considerable burdens of cyathostomin larvae can encyst in the large intestinal wall. The most recommended treatment against these pathogenic stages is moxidectin.

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Helminths are common pathogens of equids and anthelmintic resistance is a major issue in cyathostomin species and Parascaris equorum. At the heart of mitigating the impact of increasing anthelmintic resistance levels, is the responsible dissemination and use of these medicines following best practice principles. There is a paucity of information on interactions between horse owners and anthelmintic prescribers and how this shapes control.

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Cyathostomins are ubiquitous nematodes of horses. Once ingested, they can spend a substantial time as encysted larvae in the intestinal wall. The larvae can comprise up to 90% of the total burden, with up to several million worms reported in individuals.

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Teladorsagia circumcincta is a major cause of ovine parasitic gastroenteritis in temperate climatic regions. The development of high levels of anthelmintic resistance in this nematode species challenges its future control. Recent research indicates that many parasite species release extracellular vesicles into their environment, many of which have been classified as endocytic in origin, termed exosomes.

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Objective: To determine whether preoperative electrocardiographic measurements linked to sympathetic nervous activity could be used to predict recovery quality after general anaesthesia in horses.

Study Design: Prospective, clinical study.

Animals: Eighteen adult client-owned horses.

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