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.
Observations on vaccine and post-infection immunity in contagious equine metritis. The vaccination of four ponies on two occasions with a formolised culture of Haemophilus equigenitalis produced a high circulating antibody titre to the organism in each pony. Three out of four vaccinated and all of three unvaccinated ponies developed typical symptoms of contagious equine metritis (CEM) when subsequently challenged with a vaginal exudate containing H equigenitalis. Similarly, three ponies which had previously been infected with H equigenitalis and which had recovered spontaneously also developed contagious equine metritis when rechallenged with the organism. The clinical and b...
The reverse single radial immunodiffusion technique for detecting antibodies to Dermatophilus congolensis. The reverse single radial immunodiffusion technique was used to detect Dermatophilus congolensis antibody in sera collected from animals previously infected to varying levels with D congolensis. Ammonium sulphate and trichloroacetic acid extracts of five different strains of D congolensis obtained from different geographical locations were used as antigens. All the extracts showed variations in their sensitivities in detecting D congolensis antibody in the various serum samples. Multiple antibodies were detected by some extracts while some showed negative antibody reaction to all extracts. Two...
The effect of trypsin digestion on the structure and iron-donating properties of transferrins from several species. The effect of trypsin digestion on iron-saturated and iron-free (apo) human, rabbit, bovine, pig and horse tranferrins has been studied. Iron-binding fragments were produced only from iron-saturated pig and bovine transferrins although some cleavage of the polypeptide chain occurred in all cases. The apo-transferrins were generally degraded to a greater extent than the corresponding iron-saturated proteins. The ability of the different transferrins to donate iron to rabbit reticulocytes varied in the order rabbit approximately pig greater than human approximately horse greater than bovine. Try...
Suppressor T cells in tolerance to deaggregated horse anti-human thymocyte globulin in man. To understand the mechanism by which deaggregated horse anti-human thymocyte globulin (dATG) fails to induce untoward immunological reactions in man, three patients who received ATG and two patients who received dATG were studied for evidence of sensitization or tolerance to the foreign globulin. The ATG but not the dATG recipients developed allergic or serum sickness reactions; antihorse serum antibody could be detected in their serum and their blood cells proliferated in vitro in the presence of horse serum and secreted antihorse serum antibodies (P less than 0.001). Tolerance of the dATG re...
Negative contrast electron microscopic techniques for diagnosis of viruses of veterinary importance. Negative contrast electron microscopy (NCEM) was utilized as a routine tool in the diagnosis of viral infections of domestic and wild animals. Viruses identified by this technique were observed in infected culture systems or clinical specimens from several species including horses, cattle, sheep, dogs, cats, pigs, deer, Rocky Mountain bighorn sheep, antelope, and several avian species. Viruses were identified by NCEM based on their size, morphology, and symmetry and consisted of adenoviruses, herpesviruses, paramyxoviruses, myxoviruses, picornaviruses, parvoviruses, coronaviruses, reoviruses, ...
The immunological approach to pregnancy diagnosis: a review. The developing embryo/fetus bears antigens which are foreign to the mother and it could be expected that immune rejection of the conceptus would occur. One of the reasons why the fetus is not rejected is because a depression of the maternal immune response takes place during pregnancy. Serum from pregnant animals of several species has been shown to contain a factor, early pregnancy factor (EPF), which is immunosuppressive. EPF has been detected as early as six hours after mating and its detection could aid diagnosis of early pregnancy in all species.
Combined active-passive immunisation of horses against tetanus. The protection afforded by active, passive and combined active-passive methods of immunisation against tetanus was examined in previously unimmunised horses. Three groups of horses were injected; one with tetanus toxoid alone, one with tetanus antitoxin alone and one in which the tetanus toxoid and tetanus antitoxin were injected simultaneously. The protection afforded was determined by monitoring the levels of antitoxin achieved in the horses by each of these methods. The results obtained demonstrated the effectiveness of the combined active-passive method in affording rapid and prolonged pro...
Evaluation of the double immunodiffusion test for the diagnosis of louping ill infection. The usefulness of the double immunodiffusion test for the diagnosis of louping ill infection was investigated. Whereas louping ill viral antigen was not detected in brain material from field cases of the infection, its presence was readily confirmed in suckling mouse brain isolates of the virus. The double immunodiffusion test was found to be unreliable as a serological test for the retrospective diagnosis of louping ill infection in the horse.
Graft versus host reactions in foals with combined immunodeficiency. Nine foals with combined immunodeficiency were given hepatic and thymus cells from 68- to 110-day-old (gestational age) fetuses or peripheral blood lymphocytes from nonrelated horses. Clinical signs and lesions consistent with graft vs host reaction were observed in eight of the foals. Diarrhea was observed in these 8 foals, and ulcerative dermatitis, stomatitis, or glossitis was detected in 6 of the 8 foals. Histopathologic changes consisting of necrosis and lymphocyte infiltration were observed in liver, skin, alimentary tract, and less frequently in lymphoid tissues. Changes in complete blo...
A comparison of the complement fixation and immunofluorescent antibody tests in a survey of the prevalence of Babesia equi and Babesia caballi in horses in the Sultanate of Oman. The incidence of antibodies to Babesia equi and B. caballi in horses in the Royal Stables of His Majesty the Sultan of Oman was assessed by complement fixation (CF) and immunofluorescent antibody (IFA) tests. Two series of samples taken with a 2-year interval, mainly from animals reared in Oman, indicated a stable but high prevalence of antibodies. On the 2 occasions 94.6 and 97.7% respectively were positive to B. equi by IFA and 76.8 and 75.0% were positive by CF. For B. caballi the corresponding percentage figures were lower--67.9 and 40.9 by IFA and 30.4 and 40.9 by CF. A group of animals t...
Serum quality: an analysis of its components. Foetal and new born bovine sera, horse serum, human serum and human plasma, and protein solutions prepared from the by-products of human plasma fractionation have been analysed. Foetal bovine sera were found to have lower total protein (g/l) and % of gamma-globulin than the other sera studied while the potassium (mmol/1) was higher. Protease inhibitors could be detected in all specimens tested.
[Bacteriological studies of Haemophilus equigenitalis Taylor 1978, the causative organism of contagious equine metritis 1977 (author’s transl)]. The cultural, biochemical, antigenic and antibiotic susceptibility characteristics of 17 strains of Haemophilus equigenitalis, the causative organism of contagious equine metritis (CEM), were studied. Biochemical characteristics were investigated using both conventional method and the API ZYM system of enzyme detection. The biochemical profile of the H. equigenitalis strains was unique and differed from the other bacterial species studied under the same experimental conditions (H. influenzae and H. parainfluenzae, B. abortus and B. melitensis, P. multocida, A. calcoaceticus). The required X an...
H-Y antigen in a fertile XY female horse. The presence of significantly reduced levels of H-Y antigen in the blood of an XY mare is consistent with the view that H-Y genes comprise a system of testis determinants. Loss or suppression of a critical portion of H-Y genes and subthreshold expression of H-Y antigen could account for a failure of testicular differentiation, thereby allowing a measure of ovarian development in an XY embryo.
Simultaneous preparation of mononuclear and polymorphonuclear leucocytes from horse blood on Ficoll-Hypaque medium. Results presented show that highly purified populations of mononuclear (MN) and polymorphonuclear (PMN) leucocytes can be obtained from horse blood by a procedure similar to that previously described for the separation of these leucocytes from human blood. This involved centrifugation of horse blood on a Ficoll-Hypaque medium with a density of 1.095 g/ml. The procedure required approximately 1 h for completion and resulted in the simultaneous preparation of MN (greater than 98% purity) and PMN (greater than 96% purity) leucocytes. Cell viability exceeded 95% and cells retained immunological fu...
Pharmacological and immunological aspects of histamine release from horse leucocytes. Pharmacological histamine releasing agents, such as compound 48/80, poly-L-lysine, adrenocorticotrophic hormone (ACTH; beta 1-24 available commercially as Synacthen), catecholamines, purine bases, etc., are well known to induce histamine release from rat peritoneal mast cells and mast cells of other species; and to a lesser extent from peripheral blood leucocytes. It is reported in this paper that several of these potent histamine-releasing agents induce little or no histamine release from horse leucocytes. In particular the calcium ionophore A 23187 induced no histamine release. On the other ...
A new haemolysin from Staphylococcus aureus which lyses horse erythrocytes. A new haemolysin from Staphylococcus aureus produced opaque zones of haemolysis on horse blood agar but did not lyse equine erythrocytes suspended in phosphate-buffered saline. The haemolysin was not neutralized by normal rabbit serum and was distinct from alpha-, beta- and delta-haemolysins as well as human leucocidin. Partially purified preparations produced erythema when injected intradermally into rabbit skin.
Identification and genetics of horse lymphocyte alloantigens. Six hundred horses were tested with lymphocytotoxic antisera derived from 550 parous mares and 58 antisera produced by alloimmunization with horse blood cells. Seven equine lymphocyte specificities were identified using correlation analysis of the test data, absorption analysis and lysostripping. These specificities are expressed on lymphocytes and platelets, but not on red blood cells (RBC). Therefore, these specificities do not appear to be products of any of the eight known blood group systems of the horse. The distribution of these specificities in 113 Thoroughbred horses and 57 Arabian ho...
[Investigation of mare sera for antibodies against acholeplasmas and mycoplasmas with ther enzyme linked immunosorbent assay (ELISA) (author’s transl)]. After abortion sera were taken from 58 thoroughbred and other mares of the northwestern part of Germany and investigated by ELISA (enzyme linked immuno-sorbent assay) for antibodies against Mycoplasma equirhinis, M. subdolum, M. equigenitalium, M. pulmonis, M. felis, Acholeplasma laidlawii, A. hippikon, and A. equifetale. Reactions at serum dilutions of 1:32 and higher were considered as positive. At serum dilution 1:32 no antibodies were found in 11 sera. The remaining sera showed antibodies against one or more of the mycoplasma antigens investigated. The number of multiple reactions decrease...
Concentration of serum prealbumin (PR) protein in sick horses and its correlation to blood leucocyte count and albumin content in serum. Studies of Pr protein concentrations in sera of sick horses were carried out using ’s (1965) immunodiffusion technique. Relative values against a chosen standard of 100 were determined for a total of 102 horses. Horses with acute infections had Pr protein values significantly above the normal. The highest individual Pr protein value recorded in this group was 202. Horses suffering from acute laminitis and malignant tumours also had increased Pr protein values. There was a positive correlation between the Pr protein value and the blood leucocyte count and a negative correlation between the P...
A primary immune response to dextran B512 is followed by a period of antigen-specific immunosuppression caused by autoanti-idiotypic antibodies. After a primary immune response to the alpha 1-6 epitope of dextran B512, dextran high responder strains exhibit a specific inability to produce IgM and IgG antibodies against this epitope, although they gave an expected secondary response to horse erythrocytes. Spleen cells from dextran-primed and-suppressed mice responded well to dextran after transfer to lethally irradiated previously untreated mice, indicating that tolerance or exhaustive proliferation of dextran reactive B cells is not responsible. Thymus-dependent dextran-protein conjugates also induced specific suppression. Suppression ...