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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.
Vancomycin kinetics in plasma and synovial fluid following intravenous administration in horses. Vancomycin hydrochloride was infused intravenously (i.v.) over a 30-min period in five horses at doses of 6.6, 11.0 and 15.4 mg/kg. Vancomycin concentration in plasma and synovial fluid samples was measured using a polarization immunoassay. A pharmacokinetic model was developed to accommodate the special features of the present study. The data were described by a two compartment open model with synovial fluid as an additional compartment in exchange with plasma. Minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) were measured for Staphylococcus aureus and Enteroco...
Antibody to a recombinant merozoite protein epitope identifies horses infected with Babesia equi. Horses infected with Babesia equi were previously identified by the presence of antibodies reactive with a merozoite surface protein epitope (D. P. Knowles, Jr., L. E. Perryman, L. S. Kappmeyer, and S. G. Hennager. J. Clin. Microbiol. 29:2056-2058, 1991). The antibodies were detected in a competitive inhibition enzyme-linked immunosorbent assay (CI ELISA) by using monoclonal antibody 36/133.97, which defines a protein epitope on the merozoite surface. The gene encoding this B. equi merozoite epitope was cloned and expressed in Escherichia coli. The recombinant merozoite protein, designated equ...
Cross-species comparison of 5-lipoxygenase-activating protein. To identify regions of 5-lipoxygenase-activating protein (FLAP) important for the function of the protein and the binding of leukotriene biosynthesis inhibitors, we performed a cross-species analysis of FLAP. FLAP from all 10 mammalian species analyzed (human, monkey, horse, pig, cow, sheep, rabbit, dog, rat, and mouse) were immunologically cross-reactive and specifically bound leukotriene biosynthesis inhibitors with high affinity. Using the polymerase chain reaction, cDNA clones for FLAP from six species (monkey, horse, pig, sheep, rabbit, and mouse) were isolated and sequenced. The deduced ...
Equine uveitis. Uveitis (inflammation of the iris, ciliary body, or choroid) is a potentially blinding condition with a significant economic impact on the horse industry. Variable symptoms are described, as well as a considerable range of structural and functional sequelae. Known causes of initial episodes include bacterial, viral, traumatic, and parasitic insults, with recurrence by immunologic mechanisms. Treatment strategies and management recommendations that may reduce the incidence or severity of episodes are discussed.
Developmental regulation of class I major histocompatibility complex antigen expression by equine trophoblastic cells. Between days 36-38 of pregnancy equine trophoblastic cells of the chorionic girdle migrate and form endometrial cups. Just prior to invasion, the chorionic girdle cells express high levels of polymorphic, paternally inherited, major histocompatibility complex (MHC) class I antigens. Their descendents, the mature, invasive trophoblast cells of the endometrial cups, however, express low or undetectable levels of MHC class I antigens by day 44 of pregnancy. Experiments with MHC compatible pregnancies, the study of residual chorionic girdle cells that had failed to invade the endometrium and remai...
Equine tumor necrosis factor alpha: cloning and expression in Escherichia coli, generation of monoclonal antibodies, and development of a sensitive enzyme-linked immunosorbent assay. We describe the production and purification of recombinant equine tumor necrosis factor alpha (rETNF alpha), generation and characterization of murine monoclonal antibodies (Mabs) and rabbit polyclonal antibodies (Pabs) against ETNF alpha, and development of a sensitive enzyme-linked immunosorbent assay (ELISA). Genomic-derived DNA sequences encoding mature ETNF alpha were reconstructed by the polymerase chain reaction (PCR) and oligonucleotide-directed mutagenesis and were cloned into the vector pFLAG-1 for expression in Escherichia coli. rETNF alpha was purified by anti-FLAG immunoaffinity c...
Reduction and reoxidation of equine gonadotropin alpha-subunits. Ovine (o) and equine (e) LH alpha-subunits were reduced and reoxidized using conditions known to be effective for bovine and human alpha-subunits. The major product of oLH alpha refolding was alpha-subunit monomer. In contrast, eLH alpha formed a 121,000 mol wt aggregate. Monomeric eLH alpha was recovered, but in greatly reduced yield. To test the effects of carbohydrate variation on the aggregation of equine alpha-subunits, all of the equine gonadotropin alpha-subunits (eFSH alpha, eCG alpha, eLH alpha, and free alpha-subunit) were reduced and reoxidized. In each case, the major product was t...
Regulation of matrix metabolism in equine cartilage explant cultures by interleukin 1. Explant cultures were set up, using articular cartilage obtained from metatarsophalangeal joints of 11 horses. Explants from 2 horses were used to determine culture conditions appropriate for tissue viability. The cartilage explants maintained steady-state metabolism of proteoglycans during a 13-day evaluation period. The metabolic response of equine articular cartilage to incubation with recombinant human interleukin 1 (0.01 to 100 ng/ml) was studied, using cartilage obtained from the remaining 9 horses, age of which ranged from 3 months to 20 years. Interleukin 1 induced a dose-dependent rel...
Extended x-ray absorption fine structure studies of a retrovirus: equine infectious anemia virus cysteine arrays are coordinated to zinc. Zinc finger arrays have been established as a critical structural feature of proteins involved in DNA recognition. Retroviral nucleocapsid proteins, which are involved in the binding of viral RNA, contain conserved cysteine-rich arrays that have been suggested to coordinate zinc. We provide metalloprotein structural data from an intact virus preparation that validate this hypothesis. Extended x-ray absorption fine structure (EXAFS) spectroscopy of well-characterized and active preparations of equine infectious anemia virus, compared with a peptide with known coordination and in combination wit...
Equine lentivirus, comparative studies on four serological tests for the diagnosis of equine infectious anaemia. Serological diagnosis of equine infectious anemia is of necessity group-reactive, i.e. based on viral core protein p26, because viral envelope components as well as the host's immune response to them undergo rapid antigenic change. Since 1970 the agar gel-immunodiffusion test ("Coggins-test") has been the diagnostic method of choice. Recently, ELISA tests have been introduced for faster and theoretically more sensitive serodiagnosis, while Western blots have been used to clarify doubtful results obtained in Coggins-tests. A commercial competitive ELISA was found to give practically equivalent ...
Selective IgM deficiency and abnormal B-cell response in a foal. Selective IgM deficiency was diagnosed in a 3-month-old Standardbred colt that was referred for chronic respiratory tract disease. Immunoglobulin quantification revealed normal IgG and IgA concentrations, but undetectable IgM concentration. Stimulation of blood lymphocytes with the T-cell mitogens concanavalin A and phytohemagglutinin yielded results within the normal range. However, stimulation with the B-cell mitogen lipopolysaccharide produced no response. A B-cell defect similar to that associated with several immunodeficiency disorders in people was suggested as the cause of the IgM defic...
Comparison of antibody and cell-mediated immune responses in horses following feeding of a novel dietary antigen, ovalbumin, and rotavirus. Adult ponies which were fed ovalbumin (OVA) daily for 2 weeks had significantly greater serum anti-OVA IgG (P = 0.001) and antigen specific lymphocyte responses (P = 0.031) after intramuscular injection with OVA given with saponin than control ponies which had not been fed the antigen. This suggests that, despite the lack of evidence of B- or T-cell activation in peripheral blood during the period of OVA feeding, the animals were primed for an active secondary immune response. Adult ponies were challenged with equine rotavirus, strain H-2, but no statistically significant differences were foun...
Characterization of equine zona pellucida glycoproteins by polyacrylamide gel electrophoresis and immunological techniques. This study was designed to explore the composition of the equine zona pellucida (EZP) by one- and two-dimensional polyacrylamide gel electrophoresis (1D- and 2D-PAGE), silver staining and immunoblotting techniques. Antral follicles palpable on frozen-thawed equine ovaries were aspirated with a needle and syringe, and the resultant follicular fluid, cellular material and oocytes were pooled. Oocytes were placed in Petri dishes, moved by narrow-bore pipette to droplets of phosphate-buffered saline (PBS) and mechanically cleaned of cumulus cells. The EZP from these collected oocytes was solubiliz...
[Comparison of IgG determination in foals using commercially available rapid tests]. The three tests (EQUI Z-Test, AGLUTINADE FOAL IMMUNITY, CITE Foal IgG-Test) were evaluated for their accuracy and usefulness in the field. Single radial immunodiffusion was used as reference method. All tests were easily and rapid to perform and results were obtained within a few minutes. It was easy to get the results of the CITE Foal IgG-Test, but use of the EQUI Z-Test and the FOAL AGLUTINADE IMMUNITY-Test needed some practice to get correct results. Results obtained by the CITE Foal IgG-Test correlated to single radial immunodiffusion in 94%, those obtained by FOAL AGLUTINADE IMMUNITY-Test...
Immunoblot analysis of the humoral immune response to Pythium insidiosum in horses with pythiosis. Reactions to Pythium insidiosum by sera from horses with active pythiosis were investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. Five strains of P. insidiosum were grown in nutrient broth and then sonicated. After centrifugation, supernatant antigens were separated by SDS-PAGE. An exoantigen of Conidiobolus coronatus was also tested. Bands with molecular weights between 97,000 and 14,000 were identified by Coomassie blue and silver staining. After being transferred to nitrocellulose, the antigens were reacted against sera from six horses w...
Structural proteins of equine arteritis virus. We have recently shown that the genome of equine arteritis virus (EAV) contains seven open reading frames (ORFs). We now present data on the structural proteins of EAV and the assignment of their respective genes. Virions are composed of a 14-kDa nucleocapsid protein (N) and three membrane proteins designated M, GS, and GL. M is an unglycosylated protein of 16 kDa, and GS and GL are N-glycosylated proteins of 25 and 30 to 42 kDa, respectively. The broad size distribution of GL results from heterogeneous N-acetyllactosamine addition since it is susceptible to digestion by endo-beta-galactosidas...
Diagnostic methods for African horsesickness virus using monoclonal antibodies to structural and non-structural proteins. A panel of 32 hybridoma cell lines secreting monoclonal antibodies (MAbs) reactive with African horsesickness virus serotype 4 (AHSV-4) has been developed. Four of the MAbs recognized the major core antigen VP7, twenty recognized the outer capsid protein VP2 and eight reacted with the non-structural protein NS1. With the VP7-specific MAbs a rapid and sensitive double antibody sandwich immunoassay has been developed to detect viral antigen in infected Vero cells and in spleen tissue from AHSV-infected horses. The sensitivity of the assay is 10 ng viral antigen per 100 microliters. The NS1-speci...
Cross-reactivity between a monoclonal antibody that recognizes a tumor-associated antigen on bovine lymphosarcoma cells and blood lymphocytes from various mammalian species. Tumor-associated antigens that are expressed in lymphosarcoma B cells of cattle with enzootic bovine leukosis had been analyzed in terms of their reactivity with 13 monoclonal antibodies (MAB). By use of flow cytometry and radioimmunoprecipitation, 1 of the MAB (c143) that recognized a tumor-associated antigen cross-reacted with blood lymphocytes (BL) from various mammalian species. By use of flow cytometry, the c143 MAB reacted with 10 to 49% of BL derived from human beings, mice, dogs, horses, pigs, llamas, sheep, goats, and cattle. Titer of the c143 MAB with BL from horses, pigs, human bein...
Animal immunodeficiency viruses. Feline immunodeficiency virus (FIV) has morphological, physical and biochemical characteristics similar to human immunodeficiency virus (HIV), the cause of AIDS in man. However, it is antigenically and genetically distinct from HIV; an antigenic relatedness with equine infectious anaemia virus has been demonstrated. FIV has been molecularly cloned and sequenced. Diagnostic tests are commercially available and attempts at preparing inactivated, subunit and molecularly engineered vaccines are being made in different laboratories. During FIV infection a transient primary illness can be recognized...
Cross-reactivity of existing equine influenza vaccines with a new strain of equine influenza virus from China. A novel strain of equine influenza virus, influenza A/equine/Jilin (China)/1/89, has emerged which is genetically distinct from all earlier strains of equine influenza. It is therefore possible that the vaccines against equine influenza may be unable to protect horses against disease caused by this virus strain. In vitro serological assays established that there were low levels of immunological cross-reactivity between the new virus, the current vaccine strains and the strains of equine-2 influenza virus now in circulation.
Equine protozoal myelitis in Panamanian horses and isolation of Sarcocystis neurona. Schizonts of Sarcocystis neurona were identified microscopically in hematoxylin-eosin-stained spinal cord sections from 2 native Panamanian horses that exhibited clinical signs of equine protozoal myelitis (EPM). Spinal cord homogenate from a third Panamanian horse with EPM was inoculated onto monolayers of cultured bovine monocytes (M617). Intracytoplasmic schizonts containing merozoites arranged in rosette forms surrounding a central residual body first were observed 13 wk postinoculation. Parasites divided by endopolygeny and lacked rhoptries. Schizonts from each horse reacted with Sarcocys...
C3 fixed in vivo to cornea from horses inoculated with Leptospira interrogans. C3 was detected bound in vivo to the opaque cornea of horses inoculated with killed Leptospira interrogans. Employing epithelial corneal cells isolated from a monolayer in tissue culture, we proved that C3 is fixed in vitro to the intact cell surface after incubation with a fresh equine anti-Leptospira serum. These findings, in addition to the infiltration of cornea with neutrophils and lymphocytes, may explain the mechanisms of tissue damage in recurrent uveitis of horses with leptospirosis.
Sarcocystis neurona-associated ataxia in horses in Brazil. Sarcocystis neurona-like schizonts were found in sections of brain and spinal cord of two ataxic horses from Brazil. The diagnosis was supported by staining with anti-Sarcocystis serum in an immunohistochemical test. One of the affected horses was born in Argentina and raised in Brazil, and the other horse was born and raised in Brazil.
Keratin and associated proteins of the equine hoof wall. In this study, we described water-insoluble proteins extracted from the germinative regions (stratum internum and coronary band epithelium) and the cornified outer surface (stratum medium) of the equine hoof wall. Two major types of polypeptides were identified: the intermediate filaments (IF) and the IF-associated proteins. The IF, including keratins, composed a major portion of this fraction, had electrophoretic mobilities on sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the range of 40 to 80 kDa, and reacted with acidic or basic keratin-specific monoclonal antibodies. Differe...
Serological responses of specific pathogen-free foals to equine herpesvirus-1: primary and secondary infection, and reactivation. Serum antibody (virus neutralisation, complement fixation, IgM and IgG) responses to equine herpesvirus-1 (EHV-1) infection were measured in six foals which were initially free from EHV-1 and EHV-4 infection and maternally-derived antibodies. Following primary infection, high titres of virus neutralisation and complement fixation antibodies were detectable against EHV-1, however, corresponding antibody levels against EHV-4 were low or inapparent, although the two viruses share a number of cross-reactive epitopes. In addition, following the primary infection with EHV-1, IgM levels increased bef...
Involvement of interleukin 2 receptors in conceptus-derived suppression of T and B cell proliferation in horses. The mechanism by which a horse conceptus-derived immunosuppressive factor (HCS) of M(r) > 100,000 inhibits lymphocyte proliferation was investigated. The factor was obtained from the culture supernatants of 20-day-old horse conceptuses; activity, identified by reduced uptake of [3H]thymidine by mitogen-stimulated lymphocytes, was greatest (P < 0.01) in cultures stimulated by mitogen from pokeweed. HCS also suppressed cell proliferation stimulated by phytohaemagglutinin (P 0.05). Data from a fluorescence-activated cell sorter indicated that supplementation with HCS reduced the number of ...
Immunochemical study of equine chorionic gonadotropin (eCG/PMSG): antigenic determinants on alpha- and beta-subunits. In the present study we have established an immunochemical mapping of equine Chorionic Gonadotropin (eCG/PMSG) using three monoclonal antibodies (mAbs), namely the antibodies ECG01, E10 and D7, raised against the native hormone. These antibodies do not bind to reduced, alkylated hormone, suggesting that they recognize discontinuous rather than continuous epitopes. We have also assessed the reactivity of mAbs towards human CG, and ovine, porcine, equine and bovine LH and FSH. The antigenic determinant recognized by ECG01 is localized on the alpha-subunit of equine gonadotropins and of human CG ...
Immunokinetics of equine herpesvirus 1 in donkey mares: suppression of secondary cell-mediated response. To study the immunokinetics of equine herpesvirus 1 (EHV1), donkey mares were immunised with a laboratory strain of EHV1, or with recommended doses of Pneumabort-K vaccine (EHV1 Army 183 strain, formalin-inactivated, with an oil adjuvant) and a booster was given after three months. Humoral immune responses were studied by employing a virus neutralisation (VN) test. A leucocyte migration inhibition test (LMIT) was employed for the assay of cellular immune responses. The VN antibody titre reached 1:64 or 1:128 after primary immunisation and showed a marginal increase (1:256) after secondary immu...
