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Topic:Immunology
The equine immune system is a complex network of cells, tissues, and organs that work collaboratively to defend against pathogens and maintain homeostasis. It consists of innate and adaptive components, each with distinct functions and mechanisms. The innate immune system provides the first line of defense through physical barriers, phagocytic cells, and the complement system. The adaptive immune system involves lymphocytes, such as B cells and T cells, which generate specific responses to antigens and provide immunological memory. Research in equine immunology explores the interactions between these components, the impact of genetic and environmental factors on immune function, and the development of vaccines and therapeutics. This page gathers peer-reviewed studies and scholarly articles focusing on the mechanisms, regulation, and clinical applications of the equine immune system in health and disease.
Identification and differentiation of Taylorella equigenitalis and Taylorella asinigenitalis by lipopolysaccharide O-antigen serology using monoclonal antibodies. Lipopolysaccharides (LPSs) from Taylorella equigenitalis, the causative agent of contagious equine metritis, and T. asinigenitalis were compared by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Lipopolysaccharide profiles of 11 T. equigenitalis strains were similar, but different from the profiles of 3 T. asinigenitalis strains, and the profiles of 2 T. asinigenitalis strains were similar to each other. The serological specificities of the LPSs from these 14 strains were examined by immunoblotting and enzyme-linked immunosorbent assay with monoclonal antibodies (MAbs) ...
Molecular cloning and characterization of equine thymic stromal lymphopoietin. Thymic stromal lymphopoietin (TSLP) is a novel cytokine that plays a central role in T helper 2 (Th2) cell differentiation and allergic inflammation. It is predominantly expressed by epithelial cells, and its expression is increased in patients with atopic dermatitis and asthma. Mice overexpressing TSLP in the skin develop allergic dermatitis and mice overexpressing TSLP in lungs develop asthma-like disease. However, it is not known whether TSLP plays an important role in equine allergies. Therefore, we cloned and sequenced the complete translated region of equine TSLP gene and measured its ex...
Immunochromatographic lateral flow test for detection of antibodies to Equine infectious anemia virus. The purpose of this study was to develop and evaluate a simple immunochromatographic lateral flow (ICLF) test for specific detection of Equine infectious anemia virus (EIAV) antibodies in equine sera. Viral recombinant p26 capsid protein (rp26) was used as the capture protein in the test line and as the detector reagent conjugated to colloidal gold. The performance of rp26-ICLF was evaluated, and the results obtained were compared with a commercially available agar gel immunodiffusion (AGID) test used as a standard of comparison according to international guidelines. The values obtained for co...
Identification of Rhodococcus equi lipids recognized by host cytotoxic T lymphocytes. Immune adult horses have CD8(+) cytotoxic T lymphocytes (CTLs) that recognize and lyse Rhodococcus equi-infected cells in an equine lymphocyte alloantigen (ELA)-A [classical major histocompatibility complex (MHC) class I]-unrestricted fashion. As protein antigens are MHC class I-restricted, the lack of restriction suggests that the bacterial antigens being recognized by the host are not proteins. The goals of this study were to test the hypothesis that these CTLs recognize unique R. equi cell-wall lipids related to mycobacterial lipids. Initial experiments showed that treatment of soluble R. e...
Endotoxin-induced HIF-1alpha stabilisation in equine endothelial cells: synergistic action with hypoxia. Hypoxia may enhance the deleterious effects of lipopolysaccharide (LPS) in the endotoxaemic horse. This study has examined some of the actions of LPS and hypoxia, alone and in combination, on cultured equine digital vein endothelial cells (EDVEC) and the signalling molecules involved. Methods: EDVEC were exposed to LPS, 5% O(2) and LPS then 5% O(2) for up to 24 h. HIF-1alpha stabilisation, neutrophil adhesion and EDVEC permeability were assessed by immunoblotting, measurement of myeloperoxidase and movement of FITC-dextran, respectively. Pharmacological inhibitors were used to assess the roles...
Complement-dependent cytotoxicity assay for differentiating West Nile virus from Japanese encephalitis virus infections in horses. A complement-dependent cytotoxicity (CDC) assay was established to measure antibodies to the West Nile virus (WNV) nonstructural protein 1 (NS1) in horses. Sera collected from a WNV-infected horse mediated lysis of WNV NS1-expressing cells in a dose-dependent manner at higher percentages than sera from a Japanese encephalitis virus (JEV)-infected horse. The percentages of specific lysis for sera diluted 1:10 to 1:80 were <19.8% (assay cutoff) for almost all of the 100 JEV-infected or uninfected horses tested, in contrast to 55 to 76% in WNV-infected horses. Experimental infection revealed t...
Evaluating the effectiveness of early vaccination in the control and eradication of equine influenza–a modelling approach. In August 2007, Australia which had previously been free of equine influenza, experienced a large outbreak that lasted approximately 4 months before it was eradicated. The outbreak required a significant national response by government and the horse industries. The main components of the response were movement controls, biosecurity measures, risk-based zoning and, subsequently, vaccination to contain the outbreak. Although not initially used, vaccination became a key element in the eradication program, with approximately 140000 horses vaccinated. Vaccination is recognised as a valuable tool fo...
Characterization of extracellular matrix macromolecules in primary cultures of equine keratinocytes. Most research to date involving laminins and extracellular matrix protein function in both normal and pathological conditions involves in vitro culture of keratinocytes. Few methods are established to allow for prolonged propagation of keratinocytes from equine tissues, including the hoof lamellae. In this study we modified cell isolation and culture techniques to allow for proliferation and sub-culturing of equine lamellar keratinocytes. Additionally, the production and processing of extracellular matrix molecules by skin and lamellar keratinocytes were studied. Results: Physical and proteoly...
Complex interactions between the major and minor envelope proteins of equine arteritis virus determine its tropism for equine CD3+ T lymphocytes and CD14+ monocytes. Extensive cell culture passage of the virulent Bucyrus (VB) strain of equine arteritis virus (EAV) to produce the modified live virus (MLV) vaccine strain has altered its tropism for equine CD3(+) T lymphocytes and CD14(+) monocytes. The VB strain primarily infects CD14(+) monocytes and a small subpopulation of CD3(+) T lymphocytes (predominantly CD4(+) T lymphocytes), as determined by dual-color flow cytometry. In contrast, the MLV vaccine strain has a significantly reduced ability to infect CD14(+) monocytes and has lost its capability to infect CD3(+) T lymphocytes. Using a panel of five re...
Molecular and biological characterization of equine infectious anemia virus Rev. Equine infectious anemia virus (EIAV) is one of the most divergent members of the lentivirus subfamily of retroviruses and is considered a useful comparative model for molecular studies of lentivirus replication. The Rev protein of EIAV is functionally homologous with other lentiviral Revs and facilitates export of incompletely spliced viral mRNAs through a Crm1-dependent pathway. The trans- and cis-acting elements that mediate EIAV Rev function are similar to, but distinct from, the well-characterized elements in human immunodeficiency virus (HIV-1), the prototypical Rev protein. In addition,...
Virulence determinants of equine infectious anemia virus. Equine infectious anemia virus (EIAV) is a macrophage-tropic lentivirus that rapidly Induces disease in experimentally infected horses. Because EIAV infection and replication is centered on the monocyte/macrophage and has a pronounced acute disease stage, it is a useful model system for understanding the contribution of monocyte/macrophages to other lentivirus-induced diseases. Genetic mapping studies utilizing chimeric proviruses in which parental viruses are acutely virulent or avirulent have allowed the identification of important regions that influence acute virulence. U3 regions in the vi...
Identification of immunologically relevant genes in mare and foal dendritic cells responding to infection by Rhodococcus equi. Rhodococcus equi is a facultative intracellular bacterial pathogen of horses; infected foals develop pyogranulomatous pneumonia, however adult horses are largely unaffected. R. equi infects and proliferates within host macrophages and dendritic cells (DCs). DCs initiate the appropriate adaptive immune response, thereby playing a critical role in determining the outcome of infection. Our aim was to identify genes that are differentially expressed in R. equi infected monocyte-derived DCs (mdDCs). Peripheral blood monocytes from mares and foals were used to derive mdDCs by culturing with recombin...
Intradermal testing of horses with and without insect bite hypersensitivity in The Netherlands using an extract of native Culicoides species. Intradermal tests using a Culicoides nubeculosus extract have proven unreliable for diagnosis of equine insect bite hypersensitivity (IBH) in the Netherlands. The aim of this study was to evaluate the diagnostic value of an extract derived from the Dutch species C. obsoletus and C. pulicaris. Thirteen pairs of horses were tested, each pair consisting of one horse with IBH and the other a healthy control. Each horse was injected intradermally with 0.1 mL of three concentrations of Culicoides whole body extract (1 : 1000 w/v, 1 : 10,000 w/v and 1 : 25,000 w/v), histamine solution (0.01 mg/mL, po...
After-hours equine emergency admissions at a university referral hospital (1998-2007): causes and interventions. Medical records of equine after-hours admissions from 1998 to 2007 are reviewed. Data extracted from the medical records included signalment, reason for admission, pre-admission treatment, clinical presentation, procedures performed, final diagnoses, complications occurring in hospital, length of stay and outcome. Eight hundred and twenty after-hours admissions were available of which 75% were classified as emergencies. Most horses originated from Gauteng province (82%), with Thoroughbred, Arabian, and Warmbloods representing 46%, 10% and 7% of horses. Horses had a median age of 7 years and we...
[Antimicrobial susceptibility and resistance genes among Salmonella enterica Serovar Weltevreden isolates from humans, farm animals, and the environment in Okinawa Prefecture between 1992 and 2007]. Between 1992 and 2007, a total of 86 isolates of Salmonella enterica Weltevreden were obtained from clinical human samples (n = 41), 45 farm animals and their environment on 20 farms, including poultry (n = 25), beef cattle (n = 5), swine (n = 5), dairy cattle (n = 3), mice (n = 2), pony (n = 1), fly (n = 1) and feed samples (n = 3), in Okinawa Prefecture, Japan. Only seven isolates (8.1%) of the isolates were resistance to one or more antimicrobial agents tested; six streptomycin (7.0%), six oxytetracycline (7.0%), two ampicillin (2.3%), two kanamycin, (2.3%), two chloramphenicol (2.3%), two ...
Detection and genetic characterisation of vanA-containing Enterococcus strains in healthy Lusitano horses. Lusitano horses were investigated in order to detect the presence of vancomycin-resistant enterococci. vanA isolates showed high level vancomycin (Minimum inhibitory concentration; MIC > or = 128 mg/l) and teicoplanin resistance (MIC 64 mg/l), as well as resistance to ciprofloxacin, erythromycin and tetracycline. The tet(L) and erm(B) genes, associated with tetracycline and erythromycin resistance, respectively, were found in all vanA isolates. The intestinal tract of Lusitano horses can be a potential reservoir for vanA-containing enterococci.
A seroepidemiological study of exposure to Toxoplasma, Leishmania, Echinococcus and Trichinella in equids in Greece and analysis of risk factors. The role of horses in the transmission of parasitic zoonoses either as a source of infection to vectors or through contamination of definitive hosts is gaining importance worldwide. For this reason sera from 773 equids including 753 horses, 13 mules and seven ponies in four regions of Greece were investigated by ELISA for the presence of IgG antibodies against Toxoplasma, Leishmania, Echinococcus and Trichinella. Anti-Toxoplasma antibodies were detected in all regions with an overall prevalence of 1.8%. In contrast, antibodies to Leishmania, Echinococcus, and Trichinella were present only in h...
Gene-based vaccines: Recent developments. Gene-based vaccines are under development for a broad variety of applications, ranging from vaccines to immunotherapies for infectious diseases, cancer, autoimmune diseases and allergy. In addition, following the licensing of DNA vaccines for use in fish and horses, and DNA immunotherapy for the treatment of cancer in dogs, several veterinary uses of vaccines have been demonstrated for species ranging from fish and shrimp to cattle and horses. A variety of publications describing preclinical and clinical studies of the technologies used to increase the potency of gene-based vaccines, and resea...
An inactivated Vero cell-grown Japanese encephalitis vaccine formulated with Advax, a novel inulin-based adjuvant, induces protective neutralizing antibody against homologous and heterologous flaviviruses. Advax is a polysaccharide-based adjuvant that potently stimulates vaccine immunogenicity without the increased reactogenicity seen with other adjuvants. This study investigated the immunogenicity of a novel Advax-adjuvanted Vero cell culture candidate vaccine against Japanese encephalitis virus (JEV) in mice and horses. The results showed that, in mice, a two-immunization, low-dose (50 ng JEV antigen) regimen with adjuvanted vaccine produced solid neutralizing immunity comparable to that elicited with live ChimeriVax-JE immunization and superior to that elicited with tenfold higher doses of a ...
Lethal toxin of Clostridium sordellii is associated with fatal equine atypical myopathy. The lethal toxin of Clostridium sordellii (TcsL) evokes severe, mostly fatal disease patterns like toxic shock syndrome in humans and animals. Since this large clostridial toxin-induced severe muscle damaging when injected intramuscularly into mice, we hypothesized that TcsL is also associated with equine atypical myopathy (EAM), a fatal myodystrophy of hitherto unknown etiology. Transmission electron microscopy revealed skeletal and heart muscles of EAM-affected horses to undergo degeneration ultrastructurally similar to the damage found in TcsL-treated mice. Performing immunohistochemistry, ...
Bovine papillomavirus type 1 E2 and E7 proteins down-regulate Toll Like Receptor 4 (TLR4) expression in equine fibroblasts. BPV-1 and less commonly BPV-2 are associated with the pathogenesis of equine skin tumours termed sarcoids. We recently documented the transcriptional changes that are induced by BPV-1 in equine fibroblasts using microarray analyses. TLR4 expression was found to be significantly down-regulated by BPV-1. In the present study, we show that TLR4 expression is significantly decreased following the exogenous expression of BPV-1 E2 and E7 in primary equine fibroblasts. The results were confirmed by the demonstration of increased TLR4 expression following siRNA suppression of BPV-1 E2 and E7 viral gen...
Analysis of MHC class I genes across horse MHC haplotypes. The genomic sequences of 15 horse major histocompatibility complex (MHC) class I genes and a collection of MHC class I homozygous horses of five different haplotypes were used to investigate the genomic structure and polymorphism of the equine MHC. A combination of conserved and locus-specific primers was used to amplify horse MHC class I genes with classical and nonclassical characteristics. Multiple clones from each haplotype identified three to five classical sequences per homozygous animal and two to three nonclassical sequences. Phylogenetic analysis was applied to these sequences, and gr...
Loop-mediated isothermal amplification assays for detection of Equid herpesvirus 1 and 4 and differentiating a gene-deleted candidate vaccine strain from wild-type Equid herpesvirus 1 strains. Loop-mediated isothermal amplification (LAMP) is a novel method for the rapid and sensitive detection of DNA without the need for expensive equipment. In the present study, LAMP assays were developed for the specific detection of Equid herpesvirus 1 and 4 (EHV-1 and EHV-4, respectively) and for the differentiation of glycoprotein E (gE)-deleted EHV-1 (DeltagE) strain, a candidate strain for a live vaccine, from field EHV-1 strains. Specific primer sets were designed for the gC and gE genes of EHV-1 and for the gC gene of EHV-4. The analytical sensitivities of the LAMP assays were compared with...
A note on langerhans cells in the oesophagus epithelium of domesticated mammals. Using the zinc-iodide osmium tetroxide (ZIO) method, TEM and immunohistochemistry (for CD1a and langerin), the study demonstrates Langerhans cells in the oesophageal epithelium of domesticated mammals (herbivores: horse, cattle, goat; omnivores: pig, dog, laboratory rat; carnivores: cat), although with variations between the species. The ZIO method and TEM showed this cell type in the cat and, sporadically, in the horse; CD1a (+) Langerhans cells were demonstrated in the ovine, porcine and murine oesophagus. Positive staining for langerin was detected in single cells of the caprine, canine, mu...
Cell-mediated immunity evaluation in foals infected with virulent equine herpesvirus-1 by multi-parameter flow cytometry. The cell-mediated immune (CMI) response of foals to virulent equine herpesvirus-1 (EHV-1) infection was evaluated by multi-parameter flow cytometry (FCM). Ten 7-8-month-old EHV-1 seronegative foals were infected intranasally with virulent EHV-1 and 10 foals served as uninfected controls. Blood samples were collected 6 and 7 weeks after infection to test for specific CMI responses to live heterologous EHV-1 recall antigen. The activation markers included major histocompatibility complex class II (MHC II), intracellular interferon gamma (IFN-gamma) and interleukin 4 (IL-4). The results from both...
Effects of pretreatment with dexamethasone or levothyroxine sodium on endotoxin-induced alterations in glucose and insulin dynamics in horses. To investigate the effects of dexamethasone or levothyroxine sodium on endotoxin-induced alterations in glucose and insulin dynamics. Methods: 24 horses. Methods: Horses were randomly allocated to 3 treatment groups and received 48 mg of levothyroxine mixed with 200 g of oats, 20 mg of dexamethasone plus oats, or oats alone (control) for 15 days, followed by IV infusion of lipopolysaccharide (20 ng/kg) while individually housed in stalls. Frequently sampled IV glucose tolerance tests were performed prior to pretreatment, after pretreatment, and 20 hours after lipopolysaccharide administration....
The presence of anti-Yersinia pseudotuberculosis immunoglobulins in equine serum. The research was conducted on clinically healthy mares (n = 40) and foals (n = 78) during Y. pseudotuberculosis associated enzootics. The animals were divided into groups: I to IV--mares, IA to IVA--their offsprings, IB to IVB--foals which mothers were not treated with any medicaments. The animals in group I, IA and IB were injected with PBS; in group II, IIA and IIB--with Y. pseudotuberculosis strain-based vaccine, in group III, IIIA and IIIB--with P. acnes strain-based immunostimulator; in group IV, IVA and IVB--with P. acnes strain-based immunostimulator and (5 days after the immunostimulat...
Evaluation of synaptophysin as an immunohistochemical marker for equine grass sickness. It has been proposed that synaptophysin, an abundant integral membrane protein of synaptic vesicles, is an immunohistochemical marker for degenerating neurons in equine grass sickness (GS). In the present study, a statistically generated decision tree based on assessment of synaptophysin-immunolabelled ileal sections facilitated correct differentiation of all 20 cases of GS and 24 cases of non-GS disease (comprising eight horses with colic, six with neuroparalytic botulism and 10 controls). This technique also facilitated correct diagnosis of GS in all three cases that had been erroneously cla...
The repertoire of equine intestinal alpha-defensins. Defensins represent an important class of antimicrobial peptides. These effector molecules of the innate immune system act as endogenous antibiotics to protect the organism against infections with pathogenic microorganisms. Mammalian defensins are classified into three distinct sub-families (alpha-, beta- and theta-defensins) according to their specific intramolecular disulfide-bond pattern. The peptides exhibit an antimicrobial activity against a broad spectrum of microorganisms including bacteria and fungi. Alpha-Defensins are primarily synthesised in neutrophils and intestinal Paneth cells....
