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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.
Distribution of fast myosin heavy chain-based muscle fibres in the gluteus medius of untrained horses: mismatch between antigenic and ATPase determinants. The distribution of muscle fibres classified on the basis of their content of different myosin heavy chain (MHC) isoforms was analysed in muscle biopsies from the gluteus medius of adult untrained horses by correlating immunohistochemistry with specific anti-MHC monoclonal antibodies and standard myofibrillar ATPase (mATPase) histochemistry. Percutaneous needle biopsies were taken at 3 depths (20, 40 and 60 mm) from 4 4-y-old Andalusian stallions. The percentage of 'pure' I MHC fibres increased whereas that for pure IIX MHC fibres decreased from the most superficial to the deepest sampling sit...
Detection of equine antibodies to babesia caballi by recombinant B. caballi rhoptry-associated protein 1 in a competitive-inhibition enzyme-linked immunosorbent assay. A competitive-inhibition enzyme-linked immunosorbent assay (cELISA) was developed for detection of equine antibodies specific for Babesia caballi. The assay used recombinant B. caballi rhoptry-associated protein 1 (RAP-1) and monoclonal antibody (MAb) 79/17.18.5, which is reactive with a peptide epitope of a native 60-kDa B. caballi antigen. The gene encoding the recombinant antigen was sequenced, and database analysis revealed that the gene product is a rhoptry-associated protein. Cloning and expression of a truncated copy of the gene demonstrated that MAb 79/17.18.5 reacts with the C-termina...
Detection of equine herpesvirus types 2 and 5 (EHV-2 and EHV-5) in Przewalski’s wild horses. In blood samples of seven captive equid species from four German zoos EHV-1 specific antibodies were detected in 76% and EHV-4 specific antibodies in 73% of the 55 animals, whereas 93% were tested positive for EHV-2 and EHV-5, respectively. In only one blood sample from a Przewalski's wild horse EHV-4 DNA was amplified by PCR. From seven Przewalski's wild horses EHV-2, and from another one EHV-5 was isolated by cocultivation. The identity of the virus isolates was verified by PCR and restriction enzyme digestion.
Immunopathology of pineal glands from horses with uveitis. Pinealitis accompanying uveitis is well established in laboratory models of experimental autoimmune uveoretinitis. In naturally occurring uveitis, pinealitis has been demonstrated in the pineal gland from a mare with active uveitis and is suspected in some human uveitides. We have evaluated pineal glands from horses with various stages of uveitis for signs of immunopathology accompanying spontaneous uveitis. Methods: Pineal glands from 10 horses with uveitis and from 13 horses without uveitis were evaluated for histochemical (H&E, collagen) and immunohistochemical (MHC class II antigen exp...
Peripheral blood lymphocyte subpopulations and immunoglobulin concentrations in healthy foals and foals with Rhodococcus equi pneumonia. Infectious diseases are common in foals aged 1-5 months. The objectives of this investigation were to evaluate immunologic parameters in foals from birth to weaning to establish reference values for the proportion of circulating lymphocytes that were helper (CD4+) or cytotoxic (CD8+) T cells, or B cells; to measure serum immunoglobulin (IgM and IgG) concentrations; and to compare these immunologic parameters to values in foals with naturally occurring Rhodococcus equi pneumonia and in adult horses. Peripheral blood lymphocyte subpopulations were determined by flow cytometric analysis, and seru...
Phenotypic analysis of bronchoalveolar lavage fluid lymphocytes in horses with chronic pulmonary disease. A panel of specific antibodies against CD3, CD4, CD5, CD8, MHC I and II was used in single and two colour flow cytometry to define T cell subpopulations in bronchoalveolar lavage fluid of horses affected with chronic obstructive pulmonary disease and of healthy controls. According to the results of the clinical examination including bronchoscopy and cytology of the tracheal aspirate the horses were divided into four groups (healthy, subclinically to mildly affected; moderately affected, and severely affected). All groups of horses had a similar percentage of CD3+ cells in the BALF. Compared to...
Effect of ischemia and reperfusion on neutrophil accumulation in equine microvascular tissue flaps. To investigate neutrophil accumulation after ischemia and reperfusion (IR) in microvascular tissue flaps in horses. Methods: Randomized controlled experiment. Methods: A total of 8 horses between 1 and 10 years of age, 4 of each sex. Methods: Control and experimental myocutaneous island flaps based on the superficial branch of the deep circumflex iliac vessels were dissected on each horse. Atraumatic vascular clamps were applied to the pedicle of the experimental flap for 90 minutes and then removed to allow reperfusion. Based on the assumption that rapid infiltration of neutrophils into affec...
Characterisation of equine T helper cells: demonstration of Th1- and Th2-like cells in long-term equine T-cell cultures. The aim of this study was to characterise CD4+T-cells in equines, as these cells are pivotal in establishing immune responses or regulating established ones. Peripheral blood mononuclear cells from a pony immunised with ovalbumin were cultured in vitro in the presence of the specific antigen and autologous antigen presenting cells. During the antigen starvation phase, cells were maintained on recombinant equine IL-2. After 35 days of culture, most of the cells were CD4+, CD8-and sIg-. Cells proliferated specifically in the presence of antigen, as tested on day 42 of culture. These cells were a...
An immunohistochemical study of interstitial cells of Cajal (ICC) in the equine gastrointestinal tract. The interstitial cells of Cajal (ICC) are c-kit immunoreactive cells of the gastrointestinal tract which are suggested to have a role in the control of intestinal motility. Cells with c-kit immunoreactivity have not been previously described in the gastrointestinal tract of the horse. Immunoreactivity for c-kit was revealed using immunohistochemical labelling with an anti-c-kit polyclonal antibody. Sections of normal gastrointestinal tissue were examined from 13 anatomically defined sites from stomach to small colon taken from horses free from gastrointestinal disease. Three types of c-kit imm...
Antigenic profile of African horse sickness virus serotype 4 VP5 and identification of a neutralizing epitope shared with bluetongue virus and epizootic hemorrhagic disease virus. African horse sickness virus (AHSV) causes a fatal disease in horses. The virus capsid is composed of a double protein layer, the outermost of which is formed by two proteins: VP2 and VP5. VP2 is known to determine the serotype of the virus and to contain the neutralizing epitopes. The biological function of VP5, the other component of the capsid, is unknown. In this report, AHSV VP5, expressed in insect cells alone or together with VP2, was able to induce AHSV-specific neutralizing antibodies. Moreover, two VP5-specific monoclonal antibodies (MAbs) that were able to neutralize the virus in a ...
Structure of mare apolactoferrin: the N and C lobes are in the closed form. The structure of mare apolactoferrin (MALT) has been determined at 3. 8 A resolution by the molecular-replacement method, using the structure of mare diferric lactoferrin (MDLT) as the search model. The MDLT structure contains two iron-binding sites: one in the N-terminal lobe, lying between domains N1 and N2, and one in the C-terminal lobe between domains C1 and C2. Both lobes have a closed structure. MALT was crystallized using the microdialysis method with 10%(v/v) ethanol in 0.01 M Tris-HCl. The structure has been refined to a final R factor of 0.20 for all data to 3.8 A resolution. Compar...
Tapeworms as a cause of intestinal disease in horses. Until recently, the equine tapeworm Anoplocephala perfoliata was difficult to diagnose and considered to be of questionable pathogenicity. Here, Chris Proudman and Sandy Trees describe recent advances in the immunodiagnosis of this parasite that have facilitated epidemiological studies. These studies suggest that A. perfoliata may be an important cause of intestinal disease in the horse and demonstrate a dose-response relationship between infection intensity and risk of disease. If tapeworm infection is a risk factor for ileocaecal colic, the identification and treatment of infected individual...
Isolation and characterization of a novel Forssman active acidic glycosphingolipid with branched isoglobo-, ganglio-, and neolacto-series hybrid sugar chains. Equine kidney and spleen contain a Forssman active glycosphingolipid, and the structure of this glycolipid has been reported to be that of a globopentaosylceramide (GalNAcalpha-1,3GalNAcbeta-1,3Galalpha-1, 4Galbeta-1,4Glcbeta-1,1'Ceramide). We found that equine kidney contains several other anti-Forssman antibody-reactive glycosphingolipids. One of these acidic Forssman active glycosphingolipids was isolated and characterized by means of NMR, mass spectrometry, permethylation studies, and TLC-immunostaining. This glycolipid contains three moles of galactose, one mole of glucose, three moles of...
Immunolocalisation of oxytocin in the equine ovary. Oxytocin has been identified in the ovaries of many species
including ruminants (Wathes and Swann 1982; Rodgers et al.
1983), pigs (Jarry etal. 1990), sub-human primates (Khan-Dawood
1998), rats (Ho and Lee 1992) and women (Schaeffer et al. 1984).
In these species ovarian oxytocin has several roles, including
control of luteal regression (Fht and Sheldrick 1983) and possibly
luteinisation (Aladin Chandrase.kher and Fortune 1990; Eispanier et
al. 1997), and involvement in ovulation (viggiano et al. 1989).
In the mare, circulating oxytocin is reported to be high in
oestrus and early dio...
A histological and immunohistochemical study of the humoral immune system of the lungs in young Thoroughbred horses. Lungs were obtained from 16 Thoroughbred horses, aged 1 day to 2 years, which had died or been humanely killed for reasons unrelated to disease of the lower respiratory tract. The lungs were then subjected to a histological and immunohistochemical examination of the humoral immune system. At birth there was no evidence of organized lymphoid tissue, and lymphocytes and plasma cells were virtually absent in all tissue compartments in the first week of life. However, by 12 weeks, foals exhibited well developed bronchus- and bronchiole-associated lymphoid tissue, but this had regressed progressive...
Modulation of allospecific CTL responses during pregnancy in equids: an immunological barrier to interspecies matings? Maternal immune recognition of the developing conceptus in equine pregnancy is characterized by the strongest and most consistent alloantibody response described in any species, a response directed almost exclusively against paternal MHC class I Ags. This work investigated the cellular immune response to paternal MHC Ags in pregnant and nonpregnant horses and donkeys, and in horses carrying interspecies hybrid mule conceptuses. We observed profound decreases in classical, MHC-restricted, CTL activity to allogeneic paternal cells in peripheral blood lymphocytes from both horse mares and donkey ...
Gag protein epitopes recognized by CD4(+) T-helper lymphocytes from equine infectious anemia virus-infected carrier horses. Antigen-specific T-helper (Th) lymphocytes are critical for the development of antiviral humoral responses and the expansion of cytotoxic T lymphocytes (CTL). Identification of relevant Th lymphocyte epitopes remains an important step in the development of an efficacious subunit peptide vaccine against equine infectious anemia virus (EIAV), a naturally occurring lentivirus of horses. This study describes Th lymphocyte reactivity in EIAV carrier horses to two proteins, p26 and p15, encoded by the relatively conserved EIAV gag gene. Using partially overlapping peptides, multideterminant and poss...
Genetic divergence with emergence of novel phenotypic variants of equine arteritis virus during persistent infection of stallions. The persistently infected carrier stallion is the critical natural reservoir of equine arteritis virus (EAV), as venereal infection of mares frequently occurs after breeding to such stallions. Two Thoroughbred stallions that were infected during the 1984 outbreak of equine viral arteritis in central Kentucky subsequently became long-term EAV carriers. EAV genomes amplified from the semen of these two stallions were compared by sequence analysis of the six 3' open reading frames (ORFs 2 through 7), which encode the four known structural proteins and two uncharacterized glycoproteins. The major ...
The gamma2 late glycoprotein K promoter of equine herpesvirus 1 is differentially regulated by the IE and EICP0 proteins. The equine herpesvirus 1 immediate-early (IE) phosphoprotein is essential for the activation of transcription from viral early and late promoters and trans-represses its own promoter. Transient-transfection assays showed that the IE protein trans-represses the gamma2 late gK promoter. Gel shift and DNase I footprinting assays demonstrated that the IE protein binds to the gK promoter sequences from -42 to -26 and from -13 to +12 that overlap the transcription initiation site (+1). These results indicated that the IE protein binds to the transcription initiation site of the gK promoter sequences...
Influence of age and plasma treatment on neutrophil phagocytosis and CD18 expression in foals. The aim of this study was to evaluate the influence of age and plasma treatment on neutrophil phagocytosis, CD18 expression and serum opsonic capacity in foals in field settings. Microbial infections constitute a large threat in young foals and neutrophil functions are crucial for the defense. Blood samples were obtained from 13 foals at seven time points between the ages of 2 and 56 days and once from 16 adult horses. Six of the foals were treated with adult plasma at the age of 1 week. Neutrophil phagocytosis of yeast after various opsonizations and the expression of complement adhesion rece...
Purification and biochemical characterization of equine pulmonary surfactant protein D. To characterize surfactant protein D (SP-D) isolated from bronchoalveolar lavage fluid (BALF) of healthy horses. Methods: BALF from 10 Thoroughbreds (5 males, 5 females; 26 to 40 months old) without history or clinical signs of respiratory tract disease. Methods: BALF was obtained and centrifuged at 33,000 X g. The supernatant was applied to a mannose-Sepharose 6B affinity column in the presence of calcium, and the bound protein fraction was analyzed by use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblot analysis; amino acid composition was determined and partial seque...
Epithelial lymphocyte and macrophage distribution in the adult and fetal equine lung. Leucocytes in the lung epithelium play an important role in the ability of an animal to respond appropriately to inhaled pathogens. The distribution of lymphoid and myeloid cells associated with the lung epithelium was examined immunohistochemically throughout the respiratory tract of four horses, comprising two adults from an abattoir, one pregnant mare, and her fetus (in the final stage of gestation). Cross and tangential cryosections were labelled with monoclonal antibodies against T-cell, B-cell, macrophage/dendritic myeloid cell, and major histocompatibility Class (MHC) II surface antigen...
Transmissibility from horses to humans of a novel paramyxovirus, equine morbillivirus (EMV). Determination of potential infectivity of a new paramyxovirus equine morbillivirus (EMV) from horses to humans and humans to humans as a result of two outbreaks in Queensland which involved 23 horses and three humans. Methods: Seroepidemiological testing using neutralizing and immunofluorescing antibodies on people with variable levels of exposure to infected horses and humans. Results: All serological testing on a total of 298 individual contacts was negative. Conclusions: While the three human cases of EMV were probably infected as a result of very close contact with horses, these data sugge...
Increased interleukin-6 activity in the serum of ponies acutely infected with equine infectious anaemia virus. Seven ponies were infected with the virulent wild-type Wyoming strain of equine infectious anaemia virus (EIAV). Infection status was monitored by serum reverse transcriptase activity, rectal temperature, and complete blood count. Preinfection serum and serum obtained during the initial febrile episode following infection were assayed for interleukin 6 (IL-6) activity. Postinfection IL-6 activity was significantly increased as compared to preinfection values. The magnitude of increase in IL-6 was positively correlated with reverse transcriptase activity (an indirect measure of viraemia) but wa...
A 105- to 94-kilodalton protein in the epididymal fluids of domestic mammals is angiotensin I-converting enzyme (ACE); evidence that sperm are the source of this ACE. SDS-PAGE analysis of luminal fluid from the ram testis and epididymis revealed a protein of about 105 kDa in the fluid in the caput epididymal region. The molecular mass of this fluid protein shifted from 105 kDa to 94 kDa in the distal caput epididymidis and remained at 94 kDa in the lower regions of the epididymis. The possible sperm origin of this protein was suggested by the decrease in intensity of a 105-kDa compound on the sperm plasma membrane extract and by its total disappearance from the fluid of animals with impaired sperm production caused by scrotal heating. The 94-kDa protein was...
Reduction of CD4+ and CD8+ T lymphocytes during febrile periods in horses experimentally infected with equine infectious anemia virus. Three horses were experimentally infected with equine infectious anemia virus (EIAV). All horses were febrile after inoculation with EIAV and then developed chronic symptoms with intermittent fever. The febrile period was characterized by a rise in body temperature with reduced PBL and erythrocyte counts. Flow cytometric analysis showed that the reduced number of lymphocytes was due to significant decreases in CD4+ and CD8+ T cells in the absence of any change in B cell number. At the end of the febrile period the body temperature began to recover and numbers of CD4+ and CD8+ T cells showed a ...
Detection and induction of equine infectious anemia virus-specific cytotoxic T-lymphocyte responses by use of recombinant retroviral vectors. Cytotoxic T lymphocytes (CTL) appear to be critical in resolving or reducing the severity of lentivirus infections. Retroviral vectors expressing the Gag/Pr or SU protein of the lentivirus equine infectious anemia virus (EIAV) were constructed and used to evaluate EIAV-specific CTL responses in horses. Three promoters, cytomegalovirus, simian virus SV40, and Moloney murine sarcoma virus (MoMSV) long terminal repeat (LTR), were used, and there was considerable variation in their ability to direct expression of Gag/Pr and SU. Vectors expressing EIAV proteins under the direction of MoMSV LTR and ...
Purification and biochemical characterization of pulmonary surfactant protein A of horses. To characterize surfactant protein isolated from bronchoalveolar lavage fluids of healthy horses. Methods: 10 Thoroughbreds (5 males, 5 females; 26 to 40 months old) that did not have a history or clinical signs of respiratory tract disease. Methods: Bronchoalveolar lavage fluid (BALF) was obtained and centrifuged at 33,000 X g. Lipid was removed from precipitated fractions by means of extraction with 1-butanol, and organic solvent-insoluble protein precipitates were dialyzed against Tris buffer. The suspension was centrifuged, and supernatant was placed in a mannose-Sepharose affinity column,...
Unique localization of protein gene product 9.5 in type B synoviocytes in the joints of the horse. Fibroblast-like (Type B) synoviocytes are cells in the synovial membrane that are responsible for production of both synovial fluid and the extracellular matrix in the synovial intima. Immunostaining of the horse synovial membrane for protein gene product (PGP) 9.5, which is a neuron-specific ubiquitin C-terminal hydrolase, demonstrated selective localization of the immunoreactivity in a synoviocyte population different from acid phosphatase-positive Type A synoviocytes. The immunoreactive cells were lined up in the synovial intima and extended dendritic processes towards the joint cavity to f...
Quantitative measurement of equine cytokine mRNA expression by polymerase chain reaction using target-specific standard curves. Quantification of cytokine mRNA using reverse transcription coupled with the polymerase chain reaction (RT-PCR) has become a corner stone of the study of cytokine regulation. Quantitative competitive RT-PCR (QCRT-PCR) is commonly accepted as a reliable method for quantifying differences in mRNA levels but is both labor- and reagent-intensive. A noncompetitive polymerase chain reaction method that utilizes cytokine-specific, plasmid-derived, standard curves was developed for the quantification of equine cytokine mRNA. The assay can be performed on minute samples of cellular material, utilizes s...
