Omneity® Pellets
All-In-One Vitamin & Mineral Pellet
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.
Use of chemotherapy for treatment of a mixed-cell thoracic lymphoma in a horse. A 4-year-old Oldenburg mare was evaluated because of signs of lower airway disease and subsequently developed bilateral pleural effusion. Neoplastic cells were not identified in the fluid sample obtained via the initial thoracocentesis. A thoracic mass was detected radiographically, but its location prevented collection of a tissue sample. A diagnosis of lymphoma was made on the basis of results of immunophenotyping of pleural fluid specimens. Treatment of thoracic lymphoma in horses has been attempted, but there are limited data regarding chemotherapeutic-induced remission. In this horse, rem...
Prevalence of antibody to Japanese encephalitis virus nonstructural 1 protein among racehorses in Japan: indication of natural infection and need for continuous vaccination. Japanese encephalitis virus (JEV) causes fatal diseases in equines as well as humans. In Japan, racehorses are vaccinated with inactivated JE vaccine every year and no equine JE cases have been reported since 1986. However, the current reduction in JEV activity in nature has raised an argument against the requirement of continuous vaccination. Here, we studied natural infection rates in racehorses to address the issue. To identify naturally-infected individuals from vaccinated populations, we used an immunostaining method for detecting antibodies to JEV nonstructural 1 (NS1) protein. A total o...
Natural killer cell receptors in the horse: evidence for the existence of multiple transcribed LY49 genes. In rodents, the Ly49 family encodes natural killer (NK) receptors interacting with classical MHC class I molecules, whereas the corresponding receptors in primates are members of the killer cell immunoglobulin-like receptor (KIR) family. Recent evidence indicates that the cattle, domestic cat, dog, and pig have a single LY49 and multiple KIR genes, suggesting that predominant NK receptors in most non-rodent mammals might be KIR. Here, we show that the horse has at least six LY49 genes, five with an immunoreceptor tyrosine-based inhibition motif (ITIM) and one with arginine in the transmembrane...
Neuropeptide distribution in the stellate ganglia of the domestic animal. We used immunohistochemical techniques to analyze the localization and distribution of the catecholamine-synthesizing enzyme tyrosine hydroxylase (TH) and the neuropeptides methionine-endephalin (M-Enk), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), calretinin (Cal), calcitonin gene-related peptide (CGRP), substance P (SP), and galanin (Gal) in the stellate ganglia of two species of domestic animal (cattle and horses). NPY, VIP and Gal immunoreactive neurons (both cell body and nerve fiber) were observed in the stellate ganglia of both animals. M-Enk and CGRP immunoreactive ne...
Efficacy and duration of immunity of a combined equine influenza and equine herpesvirus vaccine against challenge with an American-like equine influenza virus (A/equi-2/Kentucky/95). It has been recommended that modern equine influenza vaccines should contain an A/equi-1 strain and A/equi-2 strains of the American and European-like subtype. We describe here the efficacy of a modern updated inactivated equine influenza-herpesvirus combination vaccine against challenge with a recent American-like isolate of equine influenza (A/equine-2/Kentucky/95 (H3N8). The vaccine contains inactivated Influenza strains A-equine-1/Prague'56, A-equine-2/Newmarket-1/'93 (American lineage) and A-equine-2/ Newmarket-2/93 (Eurasian lineage) and inactivated EHV-1 strain RacH and EHV-4 strain V22...
Diagnosis of West Nile virus infection in horses. The North American West Nile virus (WNV) epizootic, which began in 1999, has caused significant morbidity and mortality in horses. Because experimental infection has failed to consistently produce encephalitis in inoculated horses, investigation of naturally occurring cases was used to optimize strategies for diagnosis of this disease. Although WNV RNA could be detected by reverse transcriptase-polymerase chain reaction (RT-PCR) performed on whole blood collected from both clinically affected horses and unaffected herdmates, the diagnostic sensitivity of this approach was low compared with IgM...
Influence of long terminal repeat and env on the virulence phenotype of equine infectious anemia virus. The molecular clones pSPeiav19 and p19/wenv17 of equine infectious anemia virus (EIAV) differ in env and long terminal repeats (LTRs) and produce viruses (EIAV(19) and EIAV(17), respectively) of dramatically different virulence phenotypes. These constructs were used to generate a series of chimeric clones to test the individual contributions of LTR, surface (SU), and transmembrane (TM)/Rev regions to the disease potential of the highly virulent EIAV(17). The LTRs of EIAV(19) and EIAV(17) differ by 16 nucleotides in the transcriptional enhancer region. The two viruses differ by 30 amino acids i...
Use of dapsone in the treatment of Pneumocystis carinii pneumonia in a foal. A 6-month-old male Quarter Horse was evaluated for chronic respiratory tract disease. Diagnostic investigations revealed pulmonary inflammation; Pneumocystis carinii was detected within macrophages. Lymphocyte subpopulation phenotyping and immunoglobulin concentration analysis were performed and results suggested immune suppression. Trimethoprim-sulfamethoxazole administration was initiated; the colt was discharged but was reexamined 8 days later because of profuse diarrhea and endotoxemia. Bacterial culture of feces recovered Salmonella spp resistant to trimethoprim-sulfamethoxazole, and a di...
Cross-species reactivity of seven monoclonal antibodies with equine lymphocytes by flow cytometry. The recognition of equine lymphocyte antigens by monoclonal antibodies (mAbs) directed against human CD11a, CD18, CD21, CD23, CD29 and DR, as well as mouse CD23 was studied by flow cytometry. Unlike anti-CD11a, -CD21, -CD23 and DR mAbs, anti-CD18 and CD29 mAbs labelled the same percentage of horse peripheral blood lymphocytes (PBL) as human PBL. Double-staining with anti-horse immunoglobulin antibodies showed that anti-CD21 and -CD23 mAbs are mainly bound to peripheral blood B lymphocytes. The seven mAbs were also tested on the lymph node and thymus cells. The molecular targets of anti-CD11a, ...
Postnatal development of hepatic oxidative, hydrolytic and conjugative drug-metabolizing enzymes in female horses. Little is known about the effects of aging on the hepatic drug metabolizing capacity of horses despite the relatively long lifespan characterizing this species. A wide array of cytochrome P450 (CYP)-dependent monooxygenases, carboxylesterases and transferases were assayed in liver microsomes from 50 female horses in an age range between less than 1 year to over 12 years. Rather unexpectedly, both the CYP content and the activity of NADPH cytochrome c reductase rose as a function of age. Accordingly, a general increasing trend was recorded in the rate of the in vitro metabolism of the substrate...
Immunohistochemical identification and fiber type specific localization of protein kinase C isoforms in equine skeletal muscle. To investigate whether protein kinase C (PKC) isoforms are expressed in equine skeletal muscle and determine their distribution in various types of fibers by use of immunofluorescence microscopy. Methods: 5 healthy adult Dutch Warmblood horses. Methods: In each horse, 2 biopsy specimens were obtained from the vastus lateralis muscle. Cryosections of equine muscle were stained with PKC isoform (alpha, beta1, beta2, delta, epsilon, or zeta)-specific polyclonal antibodies and examined by use of a fluorescence microscope. Homogenized muscle samples were evaluated via western blot analysis. Results...
Nucleotide sequence of equine erythropoietin and characterization of region-specific antibodies. To determine the full-length complementary DNA (cDNA) sequence of equine erythropoietin (EPO) and to develop region-specific antibodies to differentiate equine EPO (eEPO) and human EPO (hEPO). Methods: RNA and lysate extracted from renal tissues of an adult Thoroughbred. Methods: Full-length cDNA was determined by use of a reverse transcriptase-polymerase chain reaction assay and a rapid amplification of cDNA ends method. The deduced amino acid sequence was compared with sequences of EPO reported for other species. Furthermore, 4 synthetic peptides were designed in 2 distinctive parts of the e...
Molecular cloning of a Babesia caballi gene encoding the 134-kilodalton protein and evaluation of its diagnostic potential in an enzyme-linked immunosorbent assay. A Babesia caballi gene encoding the 134-kDa (BC134) protein was immunoscreened with B. caballi-infected horse serum. An enzyme-linked immunosorbent assay (ELISA) using recombinant BC134 protein could effectively differentiate B. caballi-infected horse sera from Babesia equi-infected or noninfected control horse sera. These results suggest that the recombinant BC134 protein is a potential diagnostic antigen in the detection of B. caballi infection.
Development of an immunochromatographic test with recombinant EMA-2 for the rapid detection of antibodies against Babesia equi in horses. An immunochromatographic test (BeICT) for the rapid detection of antibodies against Babesia equi was developed. It clearly differentiated B. equi-infected horses from B. caballi-infected and uninfected horses. The agreement with enzyme-linked immunosorbent assay results was 96.7% in the detection of field sera. The results suggest that BeICT is rapid, simple, reliable, and suitable for use to detect B. equi infection in the field.
Characterisation of IgG(T) serum antibody responses to two larval antigen complexes in horses naturally- or experimentally-infected with cyathostomins. Cyathostomins are the most common parasitic nematodes of horses. Larval stages, which inhabit the intestinal wall, are particularly pathogenic and can cause severe colitis and colic. Despite their clinical importance, diagnostic techniques for the prepatent stages do not exist. A method that could estimate mucosal infection intensity would have a major impact on the control and diagnosis of cyathostominosis. Here, serum IgG(T) responses to two larval antigen complexes of 25 and 20 kDa were quantified in horses with experimental infections, natural infections and in horses that presented with c...
Generation and characterisation of an equine macrophage cell line (e-CAS cells) derived from equine bone marrow cells. Macrophages play a pivotal role in the pathophysiology of many diseases by mediating the host immune response to infections and intoxications. The species-specific activation of macrophages and the differential response in cytokine production impedes the extrapolation of results between species. Therefore, the aim of this study was to isolate and immortalise macrophages from equine bone marrow (BM) cells in order to study equine-specific signalling pathways. The isolated BM-derived macrophages (referred to as e-CAS cells) showed proliferation kinetics similar to that of standardised cell lines...
Decreased expression of equine herpesvirus-1 early and late genes in the placenta of naturally aborted equine fetuses. Intrauterine infection with equine herpesvirus-1 (EHV-1) has been considered to be the consequence of transplacental transmission of the virus following maternal cell-associated viraemia. In this study the state of EHV-1 gene expression in the placenta of seven naturally aborted equine fetuses was examined. Neither lesions nor viral antigens were detected in the placenta of the fetuses. The amount of infectious virus in the placentas was considerably lower than that in the fetal lungs, which showed pneumonia and typical herpesvirus inclusions. Quantitative dot blot hybridization with probes sp...
Late domain-dependent inhibition of equine infectious anemia virus budding. The Gag proteins of a number of different retroviruses contain late or L domains that promote the release of virions from the plasma membrane. Three types of L domains have been identified to date: Pro-Thr-Ala-Pro (PTAP), Pro-Pro-X-Tyr, and Tyr-Pro-Asp-Leu. It has previously been demonstrated that overexpression of the N-terminal, E2-like domain of the endosomal sorting factor TSG101 (TSG-5') inhibits human immunodeficiency virus type 1 (HIV-1) release but does not affect the release of the PPPY-containing retrovirus murine leukemia virus (MLV), whereas overexpression of the C-terminal portion...
Spatial and temporal expression of types I and II receptors for transforming growth factor beta in normal equine skin and dermal wounds. To describe immunolocalization of TGF-beta receptors (RI and RII) in normal equine skin and in thoracic or limb wounds, healing normally or with exuberant granulation tissue (EGT). Methods: Group A: six wounds on one metacarpus and one midthoracic area. Group B: six wounds on both metacarpi, one of which was bandaged to stimulate EGT. Immunohistochemistry was used to detect RI and RII expression in wound margins. Methods: Eight horses, randomly assigned to one of two study groups. Methods: Neutralizing polyclonal anti-rabbit RI and RII antibodies were used to detect spatial expression of RI an...
Novel classical MHC class I alleles identified in horses by sequencing clones of reverse transcription-PCR products. Improved typing of horse classical MHC class I is required to more accurately define these molecules and to extend the number identified further than current serological assays. Defining classical MHC class I alleleic polymorphism is important in evaluating cytotoxic T lymphocyte (CTL) responses in horses. In this study, horse classical MHC class I genes were analyzed based on reverse transcription (RT)-PCR amplification of sequences encoding the polymorphic peptide binding region and the more conserved alpha 3, transmembrane and cytoplasmic regions followed by cloning and sequencing. Primer s...
Oral susceptibility of South African Culicoides species to live-attenuated serotype-specific vaccine strains of African horse sickness virus (AHSV). The oral susceptibility of livestock-associated South African Culicoides midges (Diptera: Ceratopogonidae) to infection with the tissue culture-attenuated vaccine strains of African horse sickness virus (AHSV) currently in use is reported. Field-collected Culicoides were fed on horse blood-virus mixtures each containing one of the seven serotype-specific vaccine strains of AHSV, namely serotypes 1, 2, 3, 4, 6, 7 and 8. The mean titres of virus in the bloodmeals for the seven vaccine strains were between 6.8 and 7.6 log10TCID50/mL. All females (n = 3262) that survived 10 days extrinsic incubati...
The equine thymus microenvironment: a morphological and immunohistochemical analysis. We characterized herein the microarchitecture of the equine thymus along with post-natal development (6 months-->18 years). Thymuses showed an involutional process, beginning before the puberty and defined by five histological grades, which consider the progressive cortical thymocyte depletion, shrinkage and rearrangement of the epithelial network and increase in extracellular matrix (ECM). A second feature of the equine thymus was the presence of eosinopoiesis, erythropoiesis, mastocytopoiesis and plasmacytogenesis. Additionally, lymphatic vessels, full of lymphocytes, were particularly pr...
Intra- and intermolecular disulfide bonds of the GP2b glycoprotein of equine arteritis virus: relevance for virus assembly and infectivity. Equine arteritis virus (EAV) is an enveloped, positive-strand RNA virus belonging to the family Arteriviridae of the order NIDOVIRALES: EAV virions contain six different envelope proteins. The glycoprotein GP(5) (previously named G(L)) and the unglycosylated membrane protein M are the major envelope proteins, while the glycoproteins GP(2b) (previously named G(S)), GP(3), and GP(4) are minor structural proteins. The unglycosylated small hydrophobic envelope protein E is present in virus particles in intermediate molar amounts compared to the other transmembrane proteins. The GP(5) and M protein...
Babesia bovis merozoites invade human, ovine, equine, porcine and caprine erythrocytes by a sialic acid-dependent mechanism followed by developmental arrest after a single round of cell fission. Babesia bovis infections have only been observed in bovine species in contrast to Babesia divergens that also can infect humans, sheep and rodents. Using an in vitro assay that assesses invasion of erythrocytes by free merozoites after a 1-h incubation period, it was shown that specificity is not determined by host-specific interactions associated with invasion. Human erythrocytes were invaded more efficiently than bovine erythrocytes whereas erythrocytes of sheep, pigs and horses were invaded only slightly less efficiently. In contrast, goat erythrocytes were refractory to efficient invasion....
Post-entry restriction of retroviral infections. Pathogenic retroviruses have driven the evolution of several dominant-acting mechanisms able to block infection and protect the host. These are exemplified by the mouse gene Fv1, which encodes a Gag-like protein able to protect against murine leukemia virus (MLV) infection. The block is saturable, occurs after reverse transcription and is directed against the viral capsid gene. Several other mammalian species are also able to block MLV infection with the same capsid specificity. A human gene with this activity has been named Ref1. Recently, primates have been shown to restrict a variety of ret...
Rhodococcus equi secreted antigens are immunogenic and stimulate a type 1 recall response in the lungs of horses immune to R. equi infection. Rhodococcus equi is an opportunistic pathogen in immunocompromised humans and an important primary pathogen in young horses. Although R. equi infection can produce life-threatening pyogranulomatous pneumonia, most foals develop a protective immune response that lasts throughout life. The antigen targets of this protective response are currently unknown; however, Mycobacterium tuberculosis is a closely related intracellular pathogen and provides a model system. Based on previous studies of M. tuberculosis protective antigens released into culture filtrate supernatant (CFS), a bacterial growth s...
Disseminated pythiosis in three horses. Three cases of equine subcutaneous pythiosis with dissemination to the internal organs were investigated. The subcutaneous lesions were observed on the mammary gland, nostrils and limbs of the infected horses. Histopathological analysis of the infected tissues revealed a strong eosinophilic reaction, with macrophages, mast cells and giant cells. Sparsely septated hyphal filaments of 4-6 microm diameter were identified in the center of the eosinophilic areas. Specific fluorescent antibody against Pythium insidiosum confirmed the hyphae in the infected tissues in three examined horses. In one of...
Characterization of the horse (Equus caballus) IGHA gene. Nucleotide sequences of the immunoglobulin constant heavy chain genes of the horse have been described for IGHM, IGHG and IGHE genes, but not for IGHA. Here, we provide the nucleotide sequence of the genomic IGHA gene of the horse ( Equus caballus), including its secretion region and the transmembrane exon. The equine IGHA gene shows the typical structure of a mammalian IGHA gene, with only three exons, separated by two introns of similar size. The hinge exon is located at the 5' end of the CH2 exon and encodes a hinge region of 11 amino acids, which contains five proline residues. The coding ...
