Omneity® Pellets
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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.
Major histocompatibility complex I mediates immunological tolerance of the trophoblast during pregnancy and may mediate rejection during parturition. During pregnancy in larger mammals, the maternal immune system must tolerate the fetus for months while resisting external infection. This tolerance is facilitated by immunological communication between the fetus and the mother, which is mediated by Major Histocompatibility Complex I (MHC I) proteins, by leukocytes, and by the cytokines secreted by the leukocytes. Fetal-maternal immunological communication also supports pregnancy by inducing physiological changes in the mother. If the mother "misunderstands" the signal sent by the fetus during pregnancy, the fetus will be miscarried or deliver...
Evaluation of a mouse model for the West Nile virus group for the purpose of determining viral pathotypes. West Nile virus (WNV; family Flaviviridae; genus Flavivirus) group members are an important cause of viral meningoencephalitis in some areas of the world. They exhibit marked variation in pathogenicity, with some viral lineages (such as those from North America) causing high prevalence of severe neurological disease, whilst others (such as Australian Kunjin virus) rarely cause disease. The aim of this study was to characterize WNV disease in a mouse model and to elucidate the pathogenetic features that distinguish disease variation. Tenfold dilutions of five WNV strains (New York 1999, MRM16 a...
Association of antibodies against Neospora caninum in mares with reproductive problems and presence of seropositive dogs as a risk factor. Sera from 112 mares from 5 horse-breeding farms was examined for the presence of antibodies to Neospora caninum and Toxoplasma gondii by an indirect fluorescent antibody test (IFAT), as well as from dogs and cattle present on these properties for the presence of antibodies to N. caninum. Among the 112 mares, 35 had a history of reproductive problems in the last breeding season and 77 had no reproductive problems. The rates of seroprevalence of N. caninum in mares with and without a history of reproductive problems were 25.71% and 6.49% and from T. gondii 2.85% and 1.29%, respectively. In dogs ...
Effects of age and macrophage lineage on intracellular survival and cytokine induction after infection with Rhodococcus equi. Rhodococcus equi, a facultative intracellular pathogen of macrophages, causes life-threatening pneumonia in foals and in people with underlying immune deficiencies. As a basis for this study, we hypothesized that macrophage lineage and age would affect intracellular survival of R. equi and cytokine induction after infection. Monocyte-derived and bronchoalveolar macrophages from 10 adult horses and from 10 foals (sampled at 1-3 days, 2 weeks, 1 month, 3 months, and 5 months of age) were infected ex vivo with virulent R. equi. Intracellular R. equi were quantified and mRNA expression of IL-1β, ...
Immunology of infective preterm delivery in the mare. Placentitis is reported to be the cause of 9.8-33.5% of abortions, stillbirths and perinatal losses in horses. Bacterial infections are responsible for 53% of placentitis cases with Streptococcus equi ssp. zooepidemicus being isolated in 28% of these cases. Clinically, mares may have a vaginal discharge, show udder development, lactate prenatally and deliver a premature or dead foal. Major aspects of the pathogenesis of infectious preterm delivery that may require more effective therapeutic targeting are myometrial contraction, immunological aspects of preterm delivery, and the effects of proi...
Structural and biochemical insights into the V/I505T mutation found in the EIAV gp45 vaccine strain. The equine infectious anemia virus (EIAV) is a lentivirus of the Retrovirus family, which causes persistent infection in horses often characterized by recurrent episodes of high fever. It has a similar morphology and life cycle to the human immunodeficiency virus (HIV). Its transmembrane glycoprotein, gp45 (analogous to gp41 in HIV), mediates membrane fusion during the infection. However, the post-fusion conformation of EIAV gp45 has not yet been determined. EIAV is the first member of the lentiviruses for which an effective vaccine has been successfully developed. The attenuated vaccine strai...
Fosfomycin: Uses and potentialities in veterinary medicine. Fosfomycin (FOS) is a natural bactericidal broad-spectrum antibiotic which acts on proliferating bacteria by inhibiting cell wall and early murein/peptidoglycan synthesis. Bactericidal activity is evident against Gram positive and Gram negative bacteria and can also act synergistically with other antibiotics. Bacterial resistance to FOS may be natural or acquired. Other properties of this drug include inhibition of bacterial adhesion to epithelial cells, exopolysaccharide biofilm penetration, immunomodulatory effect, phagocytosis promotion and protection against the nephrotoxicity caused by ot...
The expression and activity of 5-LOX in the large intestine of horses harbouring encysted cyathostomin larvae. Leukotrienes are products of the arachidonic acid metabolism and act as potent inflammatory mediators modulating the immune response and various physiological processes. This study evaluated the expression and activity of 5-lipoxygenase (5-LOX), the enzyme that catalyzes the first two steps in the biosynthesis of leukotrienes, in horses infected by larval cyathostomins. Tissue samples from dorsal and ventral colon, and from the cecum were collected from 16 horses slaughtered for human consumption. Samples were analyzed to estimate the burdens of encysted cyathostomin larvae and adult luminal s...
Expression and regulation of facilitative glucose transporters in equine insulin-sensitive tissue: from physiology to pathology. Glucose uptake is the rate-limiting step in glucose utilization in mammalians and is tightly regulated by a family of specialized proteins, called the facilitated glucose transporters (GLUTs/SLC2). GLUT4, the major isoform in insulin-responsive tissue, translocates from an intracellular pool to the cell surface and as such determines insulin-stimulated glucose uptake. However, despite intensive research over 50 years, the insulin-dependent and -independent pathways that mediate GLUT4 translocation are not fully elucidated in any species. Insulin resistance (IR) is one of the hallmarks of equin...
Equine mesenchymal stem cells inhibit T cell proliferation through different mechanisms depending on tissue source. Mesenchymal stem cells (MSCs) are used in both human clinical trials and veterinary medicine for the treatment of inflammatory and immune-mediated diseases. MSCs modulate inflammation by decreasing the cells and products of the inflammatory response. Stimulated equine MSCs from bone marrow (BM), adipose tissue (AT), cord blood (CB), and umbilical cord tissue (CT) inhibit lymphocyte proliferation and decrease inflammatory cytokine production. We hypothesized that equine MSCs inhibit T cell proliferation through secreted mediators and that MSCs from different tissue sources decrease T cell proli...
Evaluation of health status of horses immunized with snake venom and montanide adjuvants, IMS 3012 (nanoparticle), ISA 206 and ISA 35 (emulsion based) during polyvalent snake antivenom production: hematological and biochemical assessment. Several biochemical and hematological changes in horses are observed during production of snake antivenom. Although conventional adjuvants like Freund's (Complete and Incomplete) are good immunopotentiators, they produce considerable local reactions in animals. Variety of commercial adjuvants, like montanide adjuvants, having high immunopotentiation and showing lesser side effects are available. The prime objective during antivenom production is to strike a balance between safety of immunized horses and efficacy of the product. In our earlier work, efficacy of montanide group of adjuvants in a...
Gammaherpesviruses and pulmonary fibrosis: evidence from humans, horses, and rodents. Progressive lung fibrosis in humans, typified by idiopathic pulmonary fibrosis (IPF), is a serious cause of morbidity and mortality in people. Similar diseases have been described in dogs, cats, and horses. The cause and pathogenesis of such diseases in all species is poorly understood. There is growing evidence in human medicine that IPF is a manifestation of abnormal wound repair in response to epithelial injury. Because viruses can contribute to epithelial injury, there is increasing interest in a possible role of viruses, particularly gammaherpesviruses, in the pathogenesis of pulmonary fi...
Hemorrhage and blood loss-induced anemia associated with an acquired coagulation factor VIII inhibitor in a Thoroughbred mare. A 23-year-old Thoroughbred mare was evaluated because of a coagulopathy causing hemoperitoneum, hematomas, and signs of blood loss-induced anemia. Results: The mare had tachycardia, pallor, hypoperfusion, and a large mass in the right flank. The mass was further characterized ultrasonographically as an extensive hematoma in the body wall with associated hemoabdomen. Coagulation testing revealed persistent, specific prolongation of the activated partial thromboplastin time (> 100 seconds; reference interval, 24 to 44 seconds) attributable to severe factor VIII deficiency (12%; reference inte...
Equine mesenchymal stem cells from bone marrow, adipose tissue and umbilical cord: immunophenotypic characterization and differentiation potential. Studies with mesenchymal stem cells (MSCs) are increasing due to their immunomodulatory, anti-inflammatory and tissue regenerative properties. However, there is still no agreement about the best source of equine MSCs for a bank for allogeneic therapy. The aim of this study was to evaluate the cell culture and immunophenotypic characteristics and differentiation potential of equine MSCs from bone marrow (BM-MSCs), adipose tissue (AT-MSCs) and umbilical cord (UC-MSCs) under identical in vitro conditions, to compare these sources for research or an allogeneic therapy cell bank. Methods: The BM-MS...
Intravenous application of allogenic peripheral blood-derived mesenchymal stem cells: a safety assessment in 291 equine recipients. It has been reported that mesenchymal stem cells (MSCs) have homing capacities and immunomodulating effects after an intravenous injection. However, transplanting MSCs in murine tail veins can result in pulmonary reactions and even death of the animals. Unfortunately, only a few intravenous MSC transplantations have been reported in large animal species and these were performed in a limited number of individuals. To assess the safety of MSC transplantations, a large study on 291 recipient horses is reported here. MSCs were isolated from the peripheral blood (PB) of a 4-year-old and 6-year-old ...
Clinical ophthalmic challenges in the horse: a retrospective view forward. The author reviews some aspects of vision and ophthalmic disease in the horse and considers how some recent developments in ocular immunobiology and molecular pathology in other species may give pointers toward an understanding of disease processes in the horse.
Serological evidence of widespread circulation of West Nile virus and other flaviviruses in equines of the Pantanal, Brazil. A recent study reported neutralizing antibodies to West Nile virus (WNV) in horses from four ranches of southern Pantanal. To extend that study, a serosurvey for WNV and 11 Brazilian flaviviruses was conducted with 760 equines, 238 sheep and 61 caimans from 17 local cattle ranches. Among the tested equines, 32 were collected from a ranch where a neurologic disorder outbreak had been recently reported. The sera were initially screened by using a blocking ELISA and then titrated by 90% plaque-reduction neutralization test (PRNT90) for 12 flaviviruses. Employing the criterion of 4-fold greater ti...
The evaluation of three diagnostic tests for the detection of equine influenza nucleoprotein in nasal swabs. Equine influenza (EI) is a highly contagious respiratory disease of horses. Objective: The aim of this study was to evaluate two rapid antigen detection kits (Directigen or DFA, and Espline) and a commercial ELISA for the detection of EI nucleoprotein in nasal swabs. Methods: Nasal swab samples from naturally and experimentally infected horses were used to compare the sensitivity and specificity of these assays to virus isolation (VI) and real-time RT-PCR. Results: If real-time RT-PCR was considered as the gold standard, the sensitivity of the other tests in field samples was 68% (DFA), 35% (E...
Henipavirus microsphere immuno-assays for detection of antibodies against Hendra virus. Hendra and Nipah viruses (HeV and NiV) are closely related zoonotic pathogens of the Paramyxoviridae family. Both viruses belong to the Henipavirus genus and cause fatal disease in animals and humans, though only HeV is endemic in Australia. In general and due to the acute nature of the disease, agent detection by PCR and virus isolation are the primary tools for diagnostic investigations. Assays for the detection of antibodies against HeV are fit more readily for the purpose of surveillance testing in disease epidemiology and to meet certification requirements in the international movement of...
Comparison of primary vaccination regimes for equine influenza: working towards an evidence-based regime. Vaccination is crucial to the control of equine influenza (EI). The study was conducted in an effort to lay the groundwork for achieving international harmonisation of regulatory requirements based on scientific evidence of performance of different vaccination regimes. Objective: To evaluate the effectiveness of 3 different primary vaccination regimes: vaccination with the minimal intervals permitted by the racing authorities; vaccination in accordance with the manufacturer's instructions and vaccination with the longest intervals permitted by the racing authorities. Methods: Randomised, prosp...
Recent advances in understanding the pathogenesis of Lawsonia intracellularis infections. Proliferative enteropathy is an infectious disease caused by an obligate intracellular bacterium, Lawsonia intracellularis, and characterized by thickening of the intestinal epithelium due to enterocyte proliferation. The disease is endemic in swine herds and has been occasionally reported in various other species. Furthermore, outbreaks among foals began to be reported on breeding farms worldwide within the past 5 years. Cell proliferation is directly associated with bacterial infection and replication in the intestinal epithelium. As a result, mild to severe diarrhea is the major clinical si...
Neutrophil and macrophage apoptosis in bronchoalveolar lavage fluid from healthy horses and horses with recurrent airway obstruction (RAO). Dysregulation of apoptosis has been implicated in a range of diseases including tumors, neurodegenerative and autoimmune diseases, as well as allergic asthma and chronic obstructive pulmonary disease (COPD) in humans. Although it has a different pathophysiology, delayed apoptosis of various inflammatory cells may play a pivotal role in the development of recurrent airway obstruction (RAO) in horses. Reduction of inflammatory cell apoptosis or a dysregulation of this process could lead to chronic inflammation and tissue injury. Therefore, the aim of this study was to investigate the rate of apo...
Equine bone marrow-derived mesenchymal stromal cells are heterogeneous in MHC class II expression and capable of inciting an immune response in vitro. The horse is a valuable species to assess the effect of allogeneic mesenchymal stromal cells (MSCs) in regenerative treatments. No studies to date have examined recipient response to major histocompatibility complex (MHC)-mismatched equine MSCs. The purposes of this study were to immunophenotype MSCs from horses of known MHC haplotype and to compare the immunogenicity of MSCs with differing MHC class II expression. Methods: MSCs and peripheral blood leukocytes (PBLs) were obtained from Thoroughbred horses (n=10) of known MHC haplotype (ELA-A2, -A3, and -A9 homozygotes). MSCs were cultured thro...
Serodiagnosis of equine leptospirosis by enzyme-linked immunosorbent assay using four recombinant protein markers. Leptospirosis, caused by Leptospira spp., is one of the most common zoonotic diseases in the world. We tested four recombinant proteins of Leptospira interrogans, namely, rLipL21, rLoa22, rLipL32, and rLigACon4-8, to evaluate their potential for use as antigens for the diagnosis of equine leptospirosis. We employed equine sera (n = 130) that were microscopic agglutination test (MAT) negative and sera (n = 176) that were MAT positive for the 5 serovars that most commonly cause equine leptospirosis. The sensitivity and specificity of ELISA compared to MAT were 82.39% and 86.15%, respectively, fo...
Analyses of lipid rafts, Toll-like receptors 2 and 4, and cytokines in foals vaccinated with Virulence Associated Protein A/CpG oligonucleotide vaccine against Rhodococcus equi. Rhodococcus equi establishes long-term pulmonary infection, survives in phagolysosomes of alveolar macrophages and causes pneumonia in foals. The failure of the foal to clear R. equi bacteria is believed to be due to its inability to produce IFN-γ and defects in Toll-like receptor(TLR) signaling. Lipid rafts sequester immune receptors such as TLRs and facilitate efficient cell signaling and therefore, a deficiency in accumulation of receptors in lipid rafts may result in failure to activate. We tested whether a Virulence Associated Protein A (VapA)/CpG vaccine against R. equi would impact the...
Immunophenotypic characterization and tenogenic differentiation of mesenchymal stromal cells isolated from equine umbilical cord blood. Mesenchymal stem cells (MSCs) isolated from umbilical cord blood (UCB) in equines have not been well characterized with respect to the expression of pluripotency and mesenchymal markers and for tenogenic differentiation potential in vitro. The plastic adherent fibroblast-like cells isolated from 13 out of 20 UCB samples could proliferate till passage 20. The cells expressed pluripotency markers (OCT4, NANOG, and SOX2) and MSC surface markers (CD90, CD73, and CD105) by RT-PCR, but did not express CD34, CD45, and CD14. On immunocytochemistry, the isolated cells showed expression of CD90 and CD73...
Use of heavy water (D2O) in developing thermostable recombinant p26 protein based enzyme-linked immunosorbent assay for serodiagnosis of equine infectious anemia virus infection. Thermostabilizing effect of heavy water (D2O) or deuterium oxide has been demonstrated previously on several enzymes and vaccines like oral poliovirus vaccine and influenza virus vaccine. In view of the above observations, effect of heavy water on in situ thermostabilization of recombinant p26 protein on enzyme-linked immunosorbent assay (ELISA) for serodiagnosis of equine infectious anemia virus (EIAV) infection was investigated in the present study. The carbonate-bicarbonate coating buffer was prepared in 60% and 80% D2O for coating the p26 protein in 96-well ELISA plate and thermal stabilit...
Characterization of Clostridium perfringens in the feces of adult horses and foals with acute enterocolitis. Up to 60% of cases of equine colitis have no known cause. To improve understanding of the causes of acute colitis in horses, we hypothesized that Clostridium perfringens producing enterotoxin (CPE) and/or beta2 toxin (CPB2) are common and important causes of severe colitis in horses and/or that C. perfringens producing an as-yet-undescribed cytotoxin may also cause colitis in horses. Fecal samples from 55 horses (43 adults, 12 foals) with clinical evidence of colitis were evaluated by culture for the presence of Clostridium difficile, C. perfringens, and Salmonella. Feces were also examined by...
Participation of T regulatory cells in equine recurrent airway obstruction. Recurrent airway obstruction (RAO) is an equine immune-mediated disease with a high incidence worldwide. The aim of this work was to contribute to the understanding of RAO pathogenesis by studying T cells bearing regulatory markers in peripheral blood (PB) and in bronchoalveolar lavage fluid (BALF) recovered from the same group of susceptible horses before and after exposure to moldy hay, which has been shown to induce RAO signology in our horse herd. With this purpose, mononuclear cells were obtained from the BALF and PB from horses before and after antigenic challenge and were stained with f...
