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Topic:Immune Response
The immune response in horses involves a complex network of cells, tissues, and molecules that work together to protect the animal from pathogens and other harmful agents. This process includes both innate and adaptive immune mechanisms. Innate immunity provides the first line of defense and involves components such as physical barriers, phagocytic cells, and the complement system. Adaptive immunity, on the other hand, is characterized by the activation of lymphocytes and the production of antibodies, which provide a targeted response to specific antigens. Key components of the equine immune system include T cells, B cells, and various cytokines that facilitate communication between immune cells. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, regulation, and implications of immune responses in equine health.
Serum interleukin-6 concentrations in endotoxin-infused neonatal foals. Serum interleukin-6 (IL-6) concentration was measured in 11 colostrum-fed (CF) and 8 colostrum-deprived (CD) 2- to 3-day-old foals after foals were infused with lipopolysaccharide (LPS; Escherichia coli O55:B5 endotoxin, 0.5 microgram/kg of body weight in sterile saline [0.9% NaCl] solution). Four CF and 2 CD foals were given saline solution alone. Serum IL-6 concentration was estimated by use of an in vitro proliferative bioassay, using the IL-6 dependent B.13.29 clone 9 cells. Interleukin-6 concentration increased in all LPS-infused foals, and geometric mean serum IL-6 concentration was sign...
Immunoglobulin (IgG and IgA) and complement (C3) concentrations in uterine secretion following an intrauterine challenge of Streptococcus zooepidemicus in mares susceptible to versus resistant to chronic uterine infection. The validity of measuring concentrations of immunoglobulins in undiluted uterine secretions was established. The concentrations of IgG, IgA, and cleavage factor C3 of the complement system in uterine secretions were compared in mares with different resistance to chronic uterine infection (CUI). The uteri of mares susceptible (n = 6) and resistant to CUI (n = 5) were inoculated with 5 x 10(6) Streptococcus zooepidemicus when the mares were in estrus. Uterine secretions were sampled, and sampling was immediately followed by a uterine lavage at 5 and 24 h after bacterial inoculation. During a sub...
[The immunogenic properties of a recombinant vaccinia virus with an incorporated DNA copy of the 26S RNA of the Venezuelan equine encephalomyelitis virus]. A recombinant strain of vaccinia virus (VR26) containing a DNA-copy of the subgenomic 26S RNA of Venezuelan equine encephalomyelitis virus (VEE) inserted into the coding region of thymidine kinase (TK) gene was produced. This subgenomic RNA contained the genes for all structural proteins of the VEE virus, the strain Trinidad donkey (TRD). VR26 effectively expressed VEE virus glycoproteins on the membranes of the infected cells. Blood sera of VR26-immunized animals were found to contain VEE virus-specific antibodies. VR26-immunized mice and rabbits showed a high level of resistance to subcutane...
Equine infectious anemia. The ability of EIAV to persistently infect horses in the face of a profound immune response by the host makes it a potentially devastating disease for the horse population of the United States. Its ability to evade host immune defenses by lying dormant in apparently healthy animals and by rapidly changing its antigenic determinants is proving to be a major obstacle to vaccine development. Because most infected horses appear clinically normal and a large proportion of horses in this country remain untested, the virus is not likely to be eradicated in the near future. Yet, for the same reason, b...
Strangles. The etiology, epizootiology, pathogenesis, and clinical presentation of strangles are described. Streptococcus equi, the causative organism, is highly host-adapted to Equidae and shows no antigenic variation. Protective immunity apparently is mediated by a combination of serum opsonic and nasopharyngeal mucosal humoral responses. Vaccines based on M protein or inactivated bacterial suspensions may reduce the clinical attack rate by 50%, a level of protection much lower than that produced during recovery from strangles.
The equine herpesviruses. Two viruses, EHV-1 and EHV-4, are now known to be responsible for disease conditions formerly considered caused by "equine rhinopneumonitis virus." Although these viruses share several laboratory and clinical features, they differ in epidemiology and pathogenic potential. EHV-4 is primarily associated with clinical respiratory disease, whereas EHV-1 is more frequently isolated from aborted fetuses, sickly foals, and neurologic cases. Both viruses frequently establish latent infections, but the relevance of latency to clinical disease is unclear. Diagnosis based on identification of the pathoge...
Serum osteocalcin concentration in horses treated with triamcinolone acetonide. The effect of triamcinolone acetonide (0.09 mg/kg of body weight, IM) on serum osteocalcin concentration was studied. Two groups of horses were investigated and included clinically normal horses (group 1, n = 5) and horses with chronic obstructive pulmonary disease (group 2, n = 5). Before treatment, results of a t-test did not reveal any significant difference in serum osteocalcin concentration between the 2 groups. After treatment, a significant (P < 0.05) decrease in serum osteocalcin concentration was observed for both groups. Osteocalcin concentration in individual horses reached a min...
Generation and partial characterization of an eosinophil chemotactic cytokine produced by sensitized equine mononuclear cells stimulated with Strongylus vulgaris antigen. Supernatants generated by stimulation of peripheral blood mononuclear cells (PBMC) from Strongylus vulgaris sensitized or immunized ponies were assayed in vitro for eosinophil chemotactic activity (ECA) using the filter system in blind well chambers. The supernatants from these cultures were chemotactic for eosinophils, but not for neutrophils. Supernates from cultures of unsensitized PBMC stimulated with S. vulgaris antigen were not chemotactic for eosinophils. ECA was first detected in culture supernatants after 1.5 h of incubation and was dependent on both antigen and PBMC concentrations, b...
Development of neutralizing antibody in horses infected with Ehrlichia risticii. The role of the humoral immune response in ehrlichial infection is unknown. Development of neutralizing antibodies during a course of Ehrlichia risticii infection in a pony was examined in vitro by determining the inhibition of E. risticii infection of P388D1 cells in the presence of the sera. The pony experimentally infected with E. risticii developed significant neutralizing activity in the sera by 15 days postinfection when parasitemia started to decline. Neutralizing activity continued to rise after recovery from the disease up to 34 days postinfection at which time the experiment was term...
Development of a competitive enzyme-linked immunosorbent assay for detection of bovine, ovine, porcine, and equine antibodies to vesicular stomatitis virus. Two competitive (C) enzyme-linked immunosorbent assays (ELISAs) were developed for the detection of antibodies to vesicular stomatitis virus (VSV) in animal sera. The assays are based upon the availability of polyclonal antibodies (PAbs) from mouse ascitic fluids prepared against the New Jersey (NJ) and the Indiana (IN) VSV serotypes. The assays were performed by the immobilization of VSV-NJ and VSV-IN antigens on a solid phase (microtiter plate). Appropriately diluted test serum mixed with an equal volume of serotype-specific PAb was allowed to incubate in the presence of the relevant VSV ant...
Responses of horses affected with chronic obstructive pulmonary disease to inhalation challenges with mould antigens. Eight control and 8 asymptomatic COPD-affected horses were given, on separate occasions, inhalation challenges with extracts of Micropolyspora faeni, Aspergillus fumigatus and Thermoactinomyces vulgaris. All horses were also given nebulised phosphate-buffered saline (PBS) challenges and 'natural challenges' (NCs), i.e. exposure to hay and straw, as control challenges. Responses were assessed by clinical, pulmonary mechanics, arterial blood gas tensions, arterial blood pH and bronchoalveolar lavage fluid cytological examinations. PBS challenges had no effect on control or COPD-affected horses, ...
Evaluation of intradermal mould antigen testing in the diagnosis of equine chronic obstructive pulmonary disease. Intradermal end-point titres for commercial aqueous extracts of Micropolyspora faeni, Thermoactinomyces vulgaris and Aspergillus fumigatus were determined in control and chronic obstructive pulmonary disease (COPD) affected horses. The intradermal end-point titres of control and COPD-affected horses were not significantly different and values for individual horses for M. faeni, A. fumigatus and T. vulgaris were not correlated with the pulmonary dysfunction or with the bronchoalveolar lavage fluid neutrophilia which had been induced by previous inhalation challenges with these antigens and by '...
Isolation of an inhibitor of tumor necrosis factor-alpha-mediated cytotoxicity liberated from chemotaxin-stimulated equine white blood cell populations. Objectives of this investigation were to extract and isolate protein fractions inhibitory to the cytotoxic properties of tumor necrosis factor-alpha (TNF-alpha). In this context, mixed populations of WBC were harvested from equine blood and were stimulated with a combination of a synthetic chemotactic peptide and a calcium ionophore. Several methods were subsequently applied for the initial preparation of cell-free crude protein extracts, including fractional precipitation with gradient concentrations of ammonium sulfate and preparative-scale isoelectric focusing. In addition, protein fraction...
Responses of ponies to equid herpesvirus-1 ISCOM vaccination and challenge with virus of the homologous strain. An experimental (ISCOM) vaccine previously shown to protect hamsters from lethal challenge with equid herpesvirus-1 (EHV-1), was tested in horses. Vaccination with EHV-1 ISCOMs induced serum antibodies to the major virus glycoproteins gp10, 13, 14, 17, 18 and 21/22a, whereas antibody responses to gp2 were weak or absent. High levels of virus neutralising antibody of long duration were induced, but did not prevent challenge infection with virus of the homologous strain. However, in the vaccinated ponies there was a significant reduction in clinical signs, nasal virus excretion and cell associat...
Pathogenicity of a thymidine kinase-deficient mutant of equine herpesvirus 1 in mice and specific pathogen-free foals. Both intranasal (i.n.) and intracerebral (i.c.) inoculation of mice with wild-type equine herpesvirus type 1 (wt EHV-1) caused clinical signs and mortality. Virus could be recovered from target organs (turbinates, lungs and blood) for several days. By contrast, the thymidine kinase (TK)-deficient deletion mutant PR1 produced markedly less clinical disease following both i.n. and i.c. inoculation, and, in particular, no mortality occurred. PR1 did, however, establish productive infections following either route of inoculation. High titres of virus were recovered from target organs although viru...
Characterization of equine infectious anemia virus dUTPase: growth properties of a dUTPase-deficient mutant. The putative dUTPase domain was deleted from the polymerase (pol) gene of equine infectious anemia virus (EIAV) to produce a recombinant delta DUpol Escherichia coli expression cassette and a delta DU proviral clone. Expression of the recombinant delta DUpol polyprotein yielded a properly processed and enzymatically active reverse transcriptase, as determined by immunoblot analysis and DNA polymerase activity gels. Transfection of delta DU provirus into feline (FEA) cells resulted in production of virus that replicated to wild-type levels in both FEA cells and fetal equine kidney cells. In con...
Correlations between histologic endometrial lesions in mares and clinical response to intrauterine exposure with Streptococcus zooepidemicus. The relationship between histologic lesions in endometrial biopsy specimens and susceptibility to chronic uterine infection (CUI) in mares was investigated. Mares were allotted to 4 groups on the basis of degree of endometrial lesions. Mares in group 1 (n = 6) had no pathologic changes, mares in group 2 (n = 5) had only mild pathologic changes, group-3 mares (n = 7) had moderate changes, and group-4 mares (n = 7) had severe inflammatory and fibrotic endometrial changes. Susceptibility to CUI was determined by the inflammatory response to intrauterine inoculation of 5 x 10(6) Streptococcus zooe...
Quantification of histamine in plasma and pulmonary fluids from horses with chronic obstructive pulmonary disease, before and after ‘natural (hay and straw) challenges’. A commercial radioimmunoassay kit was used to quantify histamine concentrations of plasma, bronchoalveolar lavage fluid (BALF) and pulmonary epithelial lining fluid (PELF) of normal horses and horses with chronic obstructive pulmonary disease (COPD), before and after 'natural (hay and straw) challenge' (NC). There were no significant changes in the concentrations of histamine in plasma or BALF at 0.5 or 5 h after NC, but the PELF histamine concentration of COPD affected horses was significantly increased at 5 h, but not at 0.5 h, following NC. As the histamine concentrations of whole BALF lysa...
Administration of a receptor antagonist for platelet-activating factor during equine endotoxaemia. Platelet-activating factor (PAF) is an important mediator of endotoxaemia and various PAF receptor antagonists prevent many of the adverse effects of experimental endotoxaemia in laboratory animals. In this study a specific PAF receptor antagonist was used to investigate the role of PAF in equine endotoxaemia. At an interval of not greater than 10 days, 6 horses were each challenged with endotoxin and endotoxin with concurrent administration of SRI 63-441, a PAF receptor antagonist. The order of the treatments was randomised. Clinical signs, serum biochemical and coagulation profiles, and plat...
An immunohistological study of MHC class II expression and T lymphocytes in the endometrium of the mare. The distribution of T lymphocytes and of cells bearing MHC Class II antigens in the endometrium of the mare was studied using an avidin-biotin-peroxidase staining method. The cells within the endometrium which expressed MHC Class II were macrophages, lymphocytes, monocytes, dendritic cells, epithelial cells and endothelial cells. MHC Class II expression increased significantly (P < 0.05) in the luminal epithelium and tended (P = 0.0573) to increase in the subepithelial layers during oestrus. Numbers of T lymphocytes did not differ between oestrus and dioestrus. MHC Class II expression and T...
Eosinophilic synovitis following the intra-articular injection of bacterial antigen in horses. Purified streptococcal M protein was injected into one intercarpal joint in three horses hyperimmunised with Streptococcus equi M protein vaccine. The contralateral joints were injected with pH adjusted polyionic solution. All antigen-injected joints developed a severe suppurative synovitis (mean synovial fluid nucleated cell count = 102,200 x 10(6) cells litre-1). Eosinophils were found in the synovial fluid and in synovial membrane biopsy specimens of two of the horses. Immune complexes were not demonstrated in the synovial membrane. Two horses are described that developed synovial fluid eos...
The contribution of complement to opsonic activity in the uterine secretions of mares free of endometritis. The aim of the present study was to investigate if complement contributes to opsonic activity in the uterine secretions of mares with normal reproductive functions. Five mares with a mean age of 9 years were used in the study. The mares were considered to be free of endometritis based upon clinical history, palpation per rectum and ultrasonogaraphy of the genital tract, videoendoscopic inspection of the uterus, electronmicroscopy of endometrial biopsies, and bacteriological and cytological examination of swabs from the endometrium. The hormonal status of the mares was also determined. Uterine ...
Antibody responses of Japanese horses to influenza viruses in the past few years. A total of 305 horse sera collected in the Hidaka district of Hokkaido in the years 1988-90 were tested for the presence of hemagglutination-inhibition (HI) antibodies to A/equine/Newmarket/1/77 (H7N7), A/equine/Tokyo/2/71 (H3N8) and A/equine/Kentucky/1/81 (H3N8, Kentucky) strains of equine influenza (EI) virus. Antibodies to the 3 strains were detected in hardly of the 45 sera from 2-years-old horses which were collected before vaccination. Many of the 51 horses, after vaccination with inactivated EI virus, had HI antibodies to the 3 strains in 37 to 88 per cent. However, the number of positi...
A comparative review of human and equine leucocyte differentiation antigens. Monoclonal antibody technology has allowed the recognition and study of numerous leucocyte antigens in man and laboratory animals for over a decade. Numerous advances in the understanding of immune responses and immunopathology have resulted. In recent years equine researchers have started to develop similar reagents, which now offer a powerful tool to investigators of equine immunology and disease.
[Biological and parasitic variations in horses infested and reinfested by Trichinella spiralis]. Seven mares were infected with 20,000 Trichinella spiralis larvae; 2 of them were reinfected 22 wk later with the same amount of larvae. The course of infection in horses was assessed by serology (ELISA), biochemistry (aldolase activity), parasitology and histopathology. In each animal, infection was followed by a significant rise in specific antibody titers culminating at 5-10 wk post-infection (pi) and decreasing thereafter. Reinfection was followed by a slight rise in antibody levels. Aldolase activity increased during the first infection, but was not modified by reinfection. The parasite b...
Recommendations for African horse sickness vaccines for use in nonendemic areas. African horse sickness (AHS), which causes mortality up to 95%, is caused by orbiviruses and is transmitted by Culicoides. The goal of a control and eradication program for AHS is to prevent the spread of the virus via the biological vector. Control measures include slaughter of infected animals, housing of suspected infected animals in insect-proof stalls, and vaccination. Vaccination has played a key role in eradication when AHS occurred outside of Africa. Both modified live vaccines (MLV) and inactivated vaccines have been used to control AHS. An acceptable vaccine should be: safe, efficaci...
Equine T-lymphocyte MHC II expression: variation with age and subset. This paper describes the characteristics of a monoclonal antibody (CVS10) that reacts with an equine leukocyte antigen. On the basis of tissue distribution and biochemical characteristics, this antigen is equine MHC II. The equine MHC II antigen was found on a large subset of T-lymphocytes in addition to all B-lymphocytes, as has been reported previously. In addition MHC II was found to be present on a large proportion of both the mutually exclusive equine T-lymphocyte subpopulations which express either the equine homologues of CD4, or CD8. In a study of changes in equine MHC II expression wi...
Efficacy of equine influenza vaccines for protection against A/Equine/Jilin/89 (H3N8)–a new equine influenza virus. A new H3N8 equine influenza virus [A/Equine/Jilin/1/89 (Eq/Jilin)] appeared in Northeastern China in 1989 and caused high mortality in horses; the available evidence indicates that it has not yet spread outside this region of the world. Serological analysis with postinfection ferret sera in haemagglutination inhibition (HI) tests confirmed that Eq/Jilin is antigenically distinct from H3N8 equine influenza viruses isolated between 1963 and 1991 and also showed that a current equine influenza virus [A/Equine/Alaska/1/91 (H3N8)] had undergone antigenic drift. In the present study we determine if ...
Modulation of the serological response of specific pathogen-free (EHV-free) foals to EHV-1 by previous infection with EHV-4 or a TK-deletion mutant of EHV-1. EHV-1 was inoculated into specific pathogen-free (SPF) foals in order to study uncomplicated primary responses. Infection resulted in a strong serological response recognizing EHV-1-specific antigens; this contrasts with a previous publication where a weak response was recorded in SPF animals. Antibodies to EHV-1 were readily detected by four techniques (virus neutralization, complement fixation, Western blots and immune precipitation), yet there was comparatively little cross-reaction to EHV-4 target antigen. Re-inoculation with the same virus strain stimulated antibodies to EHV-1 but no addi...
