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.
Allen BV, Frank CJ.MOST viral infections in animals, including man, have been
shown to alter the absolute and relative numbers of circulating
leucocytes. This usually causes a lymphopenia or neutropenia
but, occasionally, a lymphocytosis occurs (Gresser and Lang
1966). Several studies and reviews of respiratory viral
infections in horses have noted changes in the blood pictures
of infected animals, particularly during the early stages of the
disease (Steck and Gerber 1965; Gerber 1966, 1969; Bryans
and Gerber 1972; Hofer, Steck and Gerber 1978). The
transient nature of the leucocyte response is, probabl...
Shively MA, Banks KL, Greenlee A, Klevjer-Anderson P.Equine infectious anemia is a chronic disease of horses caused by a nononcogenic retrovirus. Studies were undertaken to determine the types of cells involved in the in vitro lymphoproliferative response to viral antigens and the dynamics of this reaction. It was observed that reactive lymphocytes were present at unpredictable times in the peripheral blood of infected horses. This reaction was shown to be specific for the interaction of equine infectious anemia virus and T lymphocytes. Enriched B-lymphocyte populations did not divide when exposed to equine infectious anemia virus. Macrophages w...
Yamagishi H, Nagamine T, Shimoda K, Ide S, Igarashi Y, Yoshioka I, Matumoto M.Single radial hemolysis (SRH), neutralization (NT), and hemagglutination inhibition (HI) tests were carried out on sera from horses immunized against the Prague and Miami strains of equine influenza virus. The HI and NT tests demonstrated good sensitivity; the sensitivity of the SRH test was somewhat lower. The NT titers of individual sera were correlated very closely with the HI titers, although the NT titers were higher. SRH zone diameters of individual sera also showed significant correlation with the NT and NI titers. The SRH test appears to be suitable for large-scale serological surveys ...
Wilson MG, Nicholson WE, Holscher MA, Sherrell BJ, Mount CD, Orth DN.Using RIAs for six regions within proopiolipomelanocortin (proOLMC), gel filtration, and electrophoresis, we studied pituitary peptides in a normal horse and one with Cushing's disease caused by a pars intermedia adenoma. Almost all immunoreactive (IR) ACTH (78%) was 4,500 mol wt (4.5K) ACTH in normal pars distalis, but it was almost 100% corticotropin-like intermediate lobe peptide (CLIP) in normal pars intermedia. alpha MSH and beta MSH were found mainly in pars intermedia: equal concentrations of the beta MSH precursors, beta-lipotropin (beta LPH) and gamma LPH, were found in pars distalis....
Camp CJ, Leid RW.A method for the isolation of equine neutrophils was developed using metrizamide cushions. A purity of greater than 95% was routinely obtained with greater than 90% viability. These cells were radiolabeled and tested for their chemotactic response in Boyden chambers to zymosan-activated equine serum, the partially purified equine complement component C5a, and formyl-L-methionyl-L-leucyl-L-phenylalanine. The time and ionic requirements for chemotaxis of radiolabeled equine neutrophils were investigated and maximal movement was observed at 2 hours' incubation and 1.0 mM Ca and 0.5 mM Mg. Dinitro...
A four-year-old thoroughbred was presented with clinical manifestations of purpura haemorrhagica. Evidence of renal involvement consistent with glomerulopathy and nephrotic syndrome, characterized by heavy proteinuria and azotaemia, became apparent and may have been exacerbated by diuretic therapy. Autopsy revealed membrano- and mesangial proliferative glomerulonephritis and chronic pleuritis. Circulating immune complexes may have been responsible for the renal diseases and the purpura.
Jörg A, Pasquier JM, Klebanoff SJ.Eosinophil peroxidase (donor: hydrogen-peroxidase oxidoreductase, EC 1.11.1.7) was isolated in a highly purified form (415/280 nm ratio, 1.05) from horse peripheral blood eosinophil. Eosinophil peroxidase was extracted from intact eosinophils (98-100% purity) or isolated eosinophil granules with 0.05 M acetate buffer (pH 4.7)/0.18 M NaCl and purified by chromatography on Sephadex G-200 and carboxymethylcellulose. Final elution was with 0.05 M acetate buffer (pH 4.7)/ 1 M NaCl. Horse eosinophil peroxidase is a strongly basic protein with bacterial properties when combined with H2O2 and iodide, ...
Issel CJ, Adams WV.A horse whose serum reacted equivocally in the agar gel immunodiffusion (AGID) test for equine infectious anemia was studied over a 3-year period. The horse remained afebrile and virus was detected in only 1 of 6 horse inoculation tests. The intensity of AGID test reactions increased temporarily following this evidence for virus. Although the AGID test reaction was equivocal and 5 of the 6 transmission attempts failed, the 1 successful transmission proved the horse was infected.
Allen PZ, Glode M, Schneerson R, Robbins JB.Hyperimmune horse serum from a single animal (horse 46) immunized with group B (strain B-11) meningococcal vaccine provides a standardized, readily available diagnostic reagent used in primary isolation medium and for serogrouping of meningococci. Identification of the heavy-chain isotypes of specific anticapsular polysaccharide and anti-lipopolysaccharide isolated from horse 46 serum revealed a differential distribution in the occurrence of immunoglobulin classes. Meningococcal anticapsular antibodies of horse 46 serum were restricted predominately to the immunoglobulin M (IgM) class, with on...
Issel CJ, Adams WV, Meek L, Ochoa R.Twenty seven adult horses positive to the agar gel immunodiffusion (AGID) test for equine infectious anemia (EIA), but with no history of clinical EIA, were used in transfusion studies to determine whether infectious EIA virus was present in 1 to 5 ml of their blood. Of 27 recipients, 21 (78%) became AGID test-positive at an average of 24 days after inoculation. Two horses that were initially negative when screened were retested and found to carry infectious virus in 5-300 ml of whole blood; the other 4 horses were not retested. Horse flies (Tabanus fuscicostatus Hine) were unable to transmit ...
Tzipori S, Makin T, Smith M, Krautil F.Colostrum-deprived, colostrum-fed or suckling foals were orally inoculated with foal rotavirus and enterotoxigenic Escherichia coli derived from a calf. Neither agent given alone caused diarrhoea in foals aged 1 or 2 days, although with rotavirus, 2 of the 3 inoculated foals became depressed 3 days after inoculation and all 3 were excreting rotavirus in the faeces. Inoculation of both agents induced diarrhoea in colostrum-deprived, colostrum-fed or suckling foals aged up to 16 days. There was an apparent age-related resistance to diarrhoea which developed between 2 and 3 weeks of age. It was r...
Liu IK, Shivers CA.Cross-reactivity tests indicated that the equine zona pellucida shares common antigen(s) with porcine zona. Porcine oocytes were therefore used to test for the presence of zona antibodies in the sera of horses. Serum samples were collected from 65 mares infertile for unexplained causes: 7 mares were strongly positive for antibodies reactive to porcine zona pellucida as determined by an indirect immunofluorescence method. Of these 7 mares, aged 8-23 years, 2 were nulliparous and 5 were multiparous. Zona-covered horse oocytes were treated with sera from 4 mares previously identified as zona posi...
Berti A, Liguri G, Stefani M, Nassi P, Ramponi G.Horse muscle acylphosphatase antibodies were obtained by immunizing rabbits with the highly purified antigen cross-linked with glutaraldehyde. Specific antibodies were purified from the immunoglobulin fraction by affinity chromatography using a matrix coupled with the pure antigen as immunoadsorbent. The purified antibodies were partially characterized by immunodiffusion and immunoprecipitin techniques. These antibodies could be used to study aspects of the muscle acylphosphatase structure, localization and other biological properties.
Laegreid WW, Breeze RG, Counts DF.1. Equine alpha 1-antitrypsin was isolated from horse plasma by a combination of ammonium sulfate and acidification precipitation followed by ion-exchange chromatography on DEAE-cellulose, molecular sieve chromatography on Sephadex G-200 and affinity chromatography on Cibacron Blue-agarose. 2. The purified protein showed a single precipitin arc on immunoelectrophoresis in agarose but gave two bands on discontinuous polyacrylamide gel electrophoresis (PAGE). 3. Both bands appeared to interact equally with trypsin and were thought to represent two isoinhibitors of equine alpha 1-AT.
Burrows R, Denyer M.The antigenic relationships between the haemagglutinins of five A/equine-1 viruses and between six A/equine-2 viruses were examined using post-infection ferret and immunized pony sera. Similar results were obtained with sera from both species for the A/equine-1 viruses and these confirmed minor antigenic differences between the prototype A/Prague 1/56 virus and viruses isolated in England in 1973 and 1977. Considerable antigenic differences were found between five of the A/equine-2 viruses, using ferret sera, but these differences were less evident using pony sera. The response of ponies to th...
Goto H, Shimizu K, Taya Y, Noda H, Tokunaga T.The antibody responses to equine influenza viruses were investigated during a postepizootic period of the disease. Serum samples were collected from a total of 128 horses on three occasions during the years 1967-77. No significant increase of hemagglutination-inhibition antibody titers to subtypes 1 and 2 of equine influenza virus were detected in any of the sera tested. The maternal hemagglutination-inhibition antibody titers of foals decreased over a four month interval. A marked increase of the titers was recognized in only the equine influenza virus vaccinated horses. These findings sugges...
Ueda Y, Sanai Y, Homma JY.Enzyme-linked immunosorbent assay (ELISA) was used for detection of immunoglobulin (Ig) M and IgG antibodies against a serologically common antigen (original endotoxin protein), protease, and elastase of Pseudomonas aeruginosa. The P aeruginosa antibody in horse sera was measured, using ELISA. Horseradish peroxidase-labeled rabbit anti-horse IgM and IgG antibodies were used for enzyme-labeled antibody conjugate. 5-Aminosalicylic acid and H2O2 were used for substrate. Sera collected from a vaccinated horse, a newborn foal, and 72 healthy racehorses were investigated for antibodies against P aer...
Peters GJ, Oosterhof A, Veerkamp JH.1. Adenosine inhibits thymidine and uridine incorporation of PHA-stimulated lymphocytes of man and horse at concentrations higher than 50 and 10 microM, respectively. Deoxyadenosine is inhibitory at concentrations higher than 100 microM. Thymidine and uridine incorporation of porcine lymphocytes are elevated 5-7-fold by 25-100 microM adenosine, deoxyadenosine, inosine and hypoxanthine. Leucine incorporation of PHA-stimulated lymphocytes was affected by adenosine and deoxyadenosine in the same way, but to a lower extent. 2. Effects of adenosine and deoxyadenosine were more pronounced at shorter...
Kydd J, Miller J, Antczak DF, Allen WR.The maternal immunological response to the developing equine fetus was investigated in 69 pregnancies of various genotypes. In normal intraspecies horse pregnancy (N = 16), 94% of mares produced strong cytotoxic antibody responses to paternal histocompatibility antigens which were first detectable between 44 and 70 days after ovulation. In all other types of pregnancy examined (intraspecies donkey, N = 19; interspecies mule, N = 6; interspecies hinny, N = 2; extraspecies horse-in-donkey, N = 3; and extraspecies donkey-in-horse, N = 21), antibody production was observed less frequently, and som...
Hanna CJ, Eyre P, Wells PW, McBeath DG.In general, 4 types of hypersensitivity reactions can be defined according to their immunological basis and clinical appearance. The differing mechanisms of these responses are described with particular reference to chemical mediators which through their pharmacological actions contribute to the clinical manifestations of hypersensitivity. Chemical mediators may exert their influence locally or systemically through their action on effector, tissues or organs and in addition, may be involved in the recruitment of cells of specific type to the site of the reaction. The possible role of these med...
Blue MG, Brady AA, Davidson JN, Kenney RM.Forty uterine fluid samples were obtained during oestrus and dioestrus of successive cycles from 4 mares classified as resistant to bacterial infection of the uterus. The flushings were assayed for peroxidase activity and ability to influence phagocytosis by polymorphonuclear neutrophils. Uterine fluid volumes and protein concentrations and serum oestrogen values were similar during oestrus and dioestrus. Serum progesterone concentrations were depressed during oestrus. Equine neutrophils adherent to glass slides were exposed to a genital strain of Streptococcus zooepidemicus suspended in salin...
Mantovani A, Caporale V, Ciuchini F, Di Trani L, Irsara A, Prosperi S.The results of antibody titrations in different animal species vaccinated against rabies are reported. The following points are considered: (1) antibody titration may be used to detect an immunity status in dogs, (2) equines should be vaccinated in infected areas, (3) experiments in progress are comparing ERA vaccine and an inactivated vaccine in bovines, and (4) the vaccination of fallow deer (Dama dama) and moufflons (Ovis ammon musimon) produced results suggesting an extension of the experiment with the purpose of vaccinating wild ruminants whenever possible.
Sugiura T, Nakajima H.An indirect hemagglutination was developed for the diagnosis of equine infectious anemia using sheep red blood cells coated with group specific virus antigen which had been highly purified by affinity chromatography. The presence of indirect hemagglutination antibodies was demonstrated in horses with equine infectious anemia since the cells were specifically agglutinated by all the serum samples obtained from experimentally infected horses. Antibodies appeared within 35 days after inoculation, and development of which coincided well with that of precipitating and complement fixing antibodies. ...
Srivastava SK, Barnum DA.Lymphocyte stimulation was observed in whole equine blood in the presence of phytohaemagglutinin and M protein extracted from a typical strain of Streptococcus equi. Blood samples were collected from several healthy horses and horse and pony foals and cultured in vitro with varying concentrations of phytohaemagglutinin and M protein for several days. Phytohaemagglutinin was found to induce lymphocyte stimulation in these animals. Highest mean stimulation indices in horse foals (49.3 +/- 24.4) and pony foals (54.7 +/- 32.0) were observed with 0.625 and 1.25 micrograms/mL phytohaemagglutinin, re...
da Silva MH, Bier OG.Horse antiserum to the venom of Crotalus durissus terrificus, A South American rattlesnake, inhibits the phospholipase activity of the crude venom. There is a close relationship between this inhibitory property and the neutralizing potency of the antiserum in vivo. This may provide the basis for a rigorous standardization of anticrotalid venom in vitro.
Harkiss GD.An isotype-specific microELISA is presented for the measurement of antibodies to equine antithymocyte globulin in human heart transplant recipients. The assay conditions were optimized and evaluated in serial samples from 40 patients receiving a cardiac allograft. The results demonstrate that despite steroid immunosuppression and T cell cytopenia the majority of patients receiving antithymocyte globulin develop significant antibody responses, with some producing very high titres. IgM and IgG isotypes tended to predominate, with peak antibody responses occurring during the second and third week...
Hammond RA, Flower RJ, Bryant CE.THE gene encoding equine inducible nitric oxide synthase (iNOS) was cloned and sequenced. The strategy consisted of the amplification by PCR of message isolated from primary cultures of equine articular chondrocytes (Frean et al 1997) treated with 100 mg mlÿ1 LPS (Escherichia coli serotype O127:B8). PCR primer pairs were generated by comparison of cross-species published iNOS nucleotide sequences. The sequences of the 30 and 50 termini were derived by the generation of PCR products spanning those regions. The assembly of sequenced PCR fragments revealed a 3930 complete nucleotide sequence wit...
Osz E, Réthy L.The authors have compared the anaphylaxis due to active and passive sensitization of mice. In the case of active sensitizing, anti-mouse anti-thymocyte horse serum (ATS), and/or normal horse serum (NHS), whereas in the case of passive sensitizing, plasma, peripheral leukocytes, spleen cells and thymocytes of sensitized animals were used. Provocation of shock was carried out by intravenous administration of ATS or NHS. Irreversible anaphylaxis occurred in a significantly higher rate in the case of ATS than NHS sensitivity, produced either actively, or passively. Differences have been found also...
Gidley-Baird AA, Teisner B, Hau J, Grudzinskas JG.An antiserum against the serum of a pregnant mare was absorbed with stallion serum. This antiserum then gave two precipitates in crossed immunoelectrophoresis with serum from pregnant mares as the antigen. The two precipitates exhibited beta-1 and alpha-2 electrophoretic mobility. Identity was demonstrated between the alpha-2 mobile protein and PMSG. The absorbed antiserum inhibited the biological action of the PMSG preparation when tested in mouse ovarian weight assays. The beta-1 mobile protein was not detected in the serum from non-pregnant mares, stallions or geldings and was detected earl...
Davies ME.A detailed study was made of 194 equine strains of E. coli, involving biochemical and serological characters. In these, the equine strains closely resembled E. coli from other sources, and shared antigenic characters with strains isolated from different animal species.