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.
BAER H, KABAT EA, KNAUB V.Blood group substances have been isolated from the saliva of human beings of blood group B and from the linings of individual horse stomachs. The properties of the human B substances are similar to those of hog and human blood group substances previously isolated. The horse substances showed lower hexosamine and reducing sugar and higher total and non-hexosamine nitrogen than do the materials from the other species. Materials isolated from individual horse stomachs possess either A or B activity or both. Certain stomachs yielded products of identical analytical composition but with neither blo...
Beermann A, Hamza E, Reinhard S, Koch C, Oberhänsli T, Unger L.We investigated microRNAs (miRNAs) as potential prognostic biomarkers for equine sarcoid (ES) disease. In a breed-, age-, and sex-matched case-controlled study involving 45 ES-affected and 15 control horses, we assessed the diagnostic, prognostic, and theragnostic value of 3 miRNAs (eca-miR-127, eca-miR-379, eca-miR-432) in horses treated with European mistletoe () extract versus placebo. Whole-blood miRNA concentrations were measured using reverse-transcription quantitative real-time PCR (RT-qPCR) at 3 different times. We found that eca-miR-432 expression was lower in ES-affected (median =â...
Friend MM, McGaffigan EM, Hall SM, Staniar WB, Smarsh DN.Early detection of inflammation using a common test could be a valuable tool for preserving horse health. Objective: This observational study aimed to identify variation in complete blood count (CBC) parameters and inflammatory indices with inflammation, and to develop reference intervals (RIs) from horses with known inflammatory states, hypothesizing that RIs developed from horses with normal acute phase protein concentrations would improve the ability to predict inflammation. Methods: Concentrations of serum amyloid A (SAA) and haptoglobin from clinically healthy horses and horses under vete...
Meiseberg LK, Mergani A, Delarocque J, Imker R, Köhn D, Wanes D, Bonilla MC, Veldhuizen EJA, von Köckritz-Blickwede M, Ohnesorge B, de Buhr N.Equine asthma (EA) is the most prevalent chronic lung disease in horses. Neutrophils are the main effector cells in severe EA. Neutrophil extracellular traps (NETs) have been described as contributors to severity in human asthma and chronic obstructive pulmonary disease. Thus, we aimed to investigate if NET-related factors in equine neutrophils, blood and bronchoalveolar lavage fluid (BALF) allow us to differentiate EA severities and to identify NET-related mechanistic insights in EA. We quantified NETs and NET-related factors in the blood and BALF of eight healthy horses and 18 horses with di...
Kingsley NB, Sandmeyer L, Dwyer A, Langefeld CD, McMullen RJ, McCue M, Lassaline M, Bellone RR.Equine recurrent uveitis (ERU), an inflammatory eye disease, is the leading cause of blindness among horses. Insidious uveitis, a form of ERU, is especially pervasive within the Appaloosa breed and is highly heritable (h = 0.68-1.0). To date only one risk locus, leopard complex (LP), has been identified, and it explained 0.16-0.33 of the heritability estimate, suggesting that insidious uveitis is a complex genetic disease within the Appaloosa horse breed with multiple unknown predisposing loci. Results: A genome-wide association study (GWAS) using relatedness, LP genotype, sex, and age as ...
Linde P, Kurihara J, Chow L, Williams ZJ, Hendrickson D, Bass L, Dow S, Pezzanite LM.Innate immune responses within the joint are now known to play a key role in osteoarthritis (OA) pathogenesis. However, comparatively little is known regarding the role of adaptive immune responses in OA, and whether they may be important for initiating and sustaining progressive low-level joint inflammation. Therefore, we evaluated spontaneous osteoarthritis in horses to investigate whether antibodies recognizing live joint cells (chondrocytes, synoviocytes) were present in blood or synovial fluid, and to identify possible cellular target antigens. We found that horses with advanced OA had an...
Feijo LS, Ledeck J, Wolfsdorf K, Ponthier J, Parry S, Felippe MJB.Associations between the immune and endocrine systems during equine pregnancy remain poorly understood. Based on the hypothesis that distinct phases of the equine healthy gestation are characterized by specific associations between circulating immunological and hormonal parameters, contributing to pregnancy maintenance, this investigation aimed to: (i) evaluate how circulating immunological and hormonal parameters change across different phases of pregnancy; (ii) investigate associations between changes in circulating immunological and hormonal parameters; and (iii) propose potential hormonal ...
Wang T, Yang X, Wang C, Wang J, Meng J, Yao X, Zeng Y, Ren W.Studying the genetic characteristics and molecular mechanisms of immune regulation in horses is of great significance for protecting their genetic resources, improving breeding strategies, and enhancing their disease resistance, thereby ensuring their healthy performance in both sports and production. Objective: This study investigates the genetic characteristics and molecular mechanisms underlying immune regulation in Yili horses, comparing them with Thoroughbreds and Kazakh horses. Methods: Blood samples from each breed were analyzed for physiological, biochemical, and immune indices alongsi...
da Silva GM, Navas C, Carvalho MB, Sampaio Y, Rocha MN, Gomes-Silva A, de Matos Guedes HL, Cunha L, Castilho LR, da Silva JL, Felicori LF.Horse immunoglobulins have been utilized for over a century in serotherapy to treat venomous animal bites and various other conditions. However, molecular-level information about these immunoglobulins remains limited, particularly regarding immunoglobulin lambda light chains (Igλ), which constitute over 90 % of circulating antibodies. Despite the sequencing of the equine genome, the International ImMunoGeneTics information system (IMGT) has not yet annotated Igλ in its database, restricting the analysis of the horse antibody repertoire. In this study, we analyzed the equine Igλ repertoire...
Salinas-Varas C, Espinosa G, Muñoz-Caro T, Conejeros I, Gärtner U, Fey K, Arnhold S, Taubert A, Hermosilla C.Neutrophil extracellular trap (NET) are thin and long web-like structures composed of DNA and antimicrobial proteins released by activated polymorphonuclear neutrophils (PMN) as part of the innate immune response. Adipose-derived stem cells (ADSCs) represent an accessible, abundant and minimal invasive source of mesenchymal stem cells (MSCs), with high regenerative potential, immunomodulatory and anti-inflammatory properties. Although recognized immunomodulatory properties of ADSCs, their interaction with PMN and their role on NET formation remains poorly characterized. The present study aimed...
Khan MZ, Ji Y, Fan X, Liu Y, Liu W, Wang C.Equine herpesvirus (EHV) infections represent a significant global veterinary and economic challenge affecting both horses and donkeys across all inhabited continents. This narrative review comprehensively examines the nine distinct EHV species (EHV-1 through EHV-9), their taxonomic classification within Alphaherpesvirinae and Gammaherpesvirinae subfamilies, and their diverse host tropism patterns. The complex molecular pathogenesis involves sophisticated viral glycoproteins (gK, gB, gC, gH, gM, gL, gG, gD, gI, gE) that orchestrate cellular invasion, immune evasion, and intercellular transmiss...
This study presents the first investigation of West Nile virus (WNV) seroprevalence among farmed horses in Kazakhstan. In 2024, a total of 368 serum samples were collected from horses across 106 settlements in 10 regions of the Republic of Kazakhstan. Using an enzyme-linked immunosorbent assay (ELISA), antibodies to WNV were detected in 32 horses (8.7%; 95% CI: 6.2-12.0%) from six regions. Among the seropositive animals, 26 (81.25%) were females and 6 (18.75%) were males, ranging in age from 1 to 19 years. No statistically significant association between sex and the presence of antibodies to W...
Cooper BL, Hobbs KJ, Bayless R, Stinson-Miller A, Gruber E, Hepworth-Warren K, Lavoie JP, Sheats MK.Severe equine asthma (sEA) is characterized by increased lower airway neutrophils that contribute to dysregulated inflammation through the release of cytokines, reactive oxygen species and neutrophil extracellular traps (NETs). NETs are composed of cell-free DNA (cfDNA) intercalated with enzymatic proteins and are known to be increased in the lower airway of asthmatic horses. The objectives of this study were two-fold: 1. Determine if cfDNA can be accurately measured in equine bronchoalveolar lavage fluid (BALF) and tracheal wash (TW) with a Qubit 4 fluorometer. 2. Determine whether Qubit-meas...
Graide H, Duysens J, Frank T, Mouithys-Mickalad A, Niesten A, Sandersen C, Ceusters J, Serteyn D.Musculoskeletal pathologies present challenges in athletic horses, often leading to functional impairment. The slow or limited regenerative capacity of bone, joint, and tendon/ligament injuries, coupled with the limitations of conventional treatments, highlights the need for innovative therapies such as ortho-biologics and mesenchymal stem/stroma cells. Traditional 2D cell culture systems with fetal bovine serum (FBS) fail to replicate the complexity of the in vivo environment, whereas 3D cultures more accurately mimic native tissue architecture and cell-cell interactions. This study describes...
Meeremans M, Devriendt B, Bairiot S, Van Poucke M, Peelman L, Demeyere K, Meyer E, Van Vlierberghe S, De Schauwer C.Macrophages play key roles in tissue homeostasis and regeneration-associated inflammation. Unlike humans, a reliable protocol to obtain and polarise equine monocyte-derived macrophages is lacking. In this study the polarisation of equine macrophages, derived from CD172a peripheral blood monocytes is described. After differentiation, IFN-γ/LPS or IL-4 were used to induce pro- and anti-inflammatory phenotypes, respectively. Evaluation criteria included morphology, mRNA (RT-qPCR) and protein expression (flow cytometry, immunofluorescence), nitric oxide and arginase production, cytokine secretion...
Zamith Cunha R, Gobbo F, Morini M, Salamanca G, Zanoni A, Bernardini C, Gramenzi A, Chiocchetti R.Evidence suggests that the endocannabinoid system (ECS) is crucial for regulating inflammation, cell proliferation and pain. The ECS is composed of cannabinoid receptors such as type 1 (CBR1), type 2 (CBR2) and GPR55, endocannabinoids and enzymes. Proteins of ECS have previously been localized in the epidermal cells of the horse hooves. Given the physio-pathological role and cellular distribution of the ECS across species, the authors hypothesized that cannabinoid receptors are expressed within the inflammatory cells, fibroblasts and endothelial cells of the equine hoof laminae, going beyond t...
Rask E, Righetti F, Ruiz A, Bjerketorp J, Frosth S, Frykberg L, Jacobsson K, Guss B, Flock JI, Henriques-Normark B, Hartman E, Gustafsson A....Infection of susceptible horses with subspecies (), the causative agent of strangles, is associated with commingling. Exposure may occur among horses at equestrian events, sales, or horses moved among different equine stabling environments. Strangles can affect all horses on a farm, leading to the death of up to 10% of cases depending on their immunity status at the time of infection, the development of complications, the success of biosecurity measures, and the use of vaccination. The current retrospective study used ELISAs to measure the exposure of horses to at a farm that experienced an...
Underberg BA, Van der Vekens E, Drews B, Kaessmeyer S.Equine laminitis is a complex and potentially fatal disease characterized by severe vascular and inflammatory alterations within the equine foot. This study aimed to develop immunohistochemistry (IHC) protocols for the detection of cyclooxygenase-2 (COX-2) and von Willebrand factor (vWF) in equine feet with and without laminitis, post-mortem perfused with paraffin oil. Unassigned: A total of 12 equine forelimbs from 8 horses were utilized in this study, divided into two study cohorts: one with laminitis and the other as a non-laminitis control. To develop the IHC protocols thoroughly, the tiss...
Sayre KC, Flores-Ahlschwede P, Wethington AB, Kahn SK, Bray JM, Volding DM, Ahlschwede S, Bordin AI, Cohen ND, Welsh TH.Transfusion of Rhodococcus equi hyperimmune plasma (REHIP) to neonatal foals is done to reduce the incidence of rhodococcal pneumonia. Objective: To determine effects in newborn foals of REHIP transfusion on serum cortisol concentrations; the association of serum cortisol concentrations with serum globulin concentration and anti-rhodococcal immunoglobulin activity; and cumulative incidence of rhodococcal pneumonia. Methods: Serum samples were collected from 356 newborn foals from 13 New York farms immediately before and after transfusion of 1 L or 2 L of REHIP. Serum samples were assayed for c...
Veit M, Matczuk AK.Equine arteritis virus (EAV) is a positive-stranded RNA virus of the Arteriviridae family. Its GP5/M dimer, the principal component of the viral envelope, mediates virus budding and serves as a key target for neutralizing antibodies. Using AlphaFold3, we predicted the 3D structure of the EAV GP5/M dimer and compared it to its homolog in porcine reproductive and respiratory syndrome virus (PRRSV). Both complexes share a conserved architecture comprising a short ectodomain, three helical transmembrane regions, and a β-sheet-rich endodomain. EAV GP5 features a longer ectodomain with four α-heli...
Conrad NL, Mazzoleni I, Abreu MC, Costa AV, Di Giácomo CP, Zorzi VSG, Leite FPL.Equine proliferative enteropathy (EPE), caused by Lawsonia intracellularis induces intestinal epithelial hyperplasia, resulting in malabsorption, weight loss, colic, and diarrhea. Despite its clinical and economic importance, no equine-specific vaccine is commercially available. Recombinant subunit vaccines are a safe and scalable alternative; however, their immunogenicity often requires improvement. Probiotic supplementation with Bacillus toyonensis may act as an immunomodulatory strategy to potentiate vaccine efficacy. This study aimed to evaluate the immunogenicity of a recombinant protein ...
Wójtowicz A, Sadowska A, Myszczyński K, Molcan T, Kaczmarek MM, Szóstek-Mioduchowska A.Fibrosis remains incompletely understood, particularly in terms of how immune mediators shape stromal programs. We used a spontaneous large‑animal model-endometrosis (equine endometrial fibrosis) to define how interleukin‑4 (IL‑4) reprograms fibroblasts from healthy and fibrotic endometrium. Primary fibroblasts were exposed to IL‑4 (10 ng/mL) for 48 or 96 h. At 48 h, bulk transcriptomes revealed 1307 differentially expressed genes (DEGs; 648 up, 659 down) and 1271 DEGs (645 up, 626 down) in fibroblasts derived from endometria without or with endometrosis, respectively. Enrichment an...
Li Z, Yu T, Ge L, Lv S, Fu Q, Shi H.Equine herpesvirus type 1 (EHV-1) is a major veterinary pathogen causing significant economic losses in the livestock industry. Despite its impact, effective vaccines and targeted antiviral strategies remain limited, largely due to an incomplete understanding of host factors regulating viral replication and pathogenesis. Unassigned: To systematically identify host genes essential for EHV-1 infection, we established a BHK-21 cell line stably expressing Cas9 and performed a genome-wide CRISPR/Cas9 knockout screen using a pooled lentiviral single-guide RNA library. Significantly enriched candidat...
Verstraete MH, Norris JK, Loux SC, De Spiegelaere W, Carossino M, Daels P, Dini P.The placenta mediates critical interactions between mother and offspring that guide development and impact long-term health. Despite its importance, the cellular organization of the equine (Equus caballus) placenta remains poorly defined. The equine epitheliochorial placenta, characterized by the absence of trophoblast invasion and prominent endocrine activity, provides a unique comparative model for studying placental cellular composition and development. Methods: We applied single-cell RNA sequencing to chorioallantois tissue collected from first-trimester (n = 1) and term (n = 2) equine...
Thieulent CJ, Sarkar S, Carossino M, Bhowmik M, Zhu H, Balasuriya UBR.Our laboratory identified the susceptible allelic variant of equine CXCL16 protein (EqCXCL16S) as an entry receptor for equine arteritis virus (EAV). However, EAV has a broad host cell tropism and infects cells that lack EqCXCL16S. Thus, we hypothesized that EAV interacts with other host cell protein(s) that facilitate EAV infection. A virus overlay protein-binding assay in combination with a Far-Western blot from EAV-susceptible equine pulmonary artery endothelial cells (EECs) and equine dermal fibroblasts (E. Derm) identified a 57 kDa protein, present in the membrane fraction of the protein ...
Beniwal N, Lal B, Mithina S, Verma CK, Kumar S, Phagna V, Jakhar K, Sonar S, Gupta V, Singh R, Kumar N, Tan CW, Thachamvally R, Singha H, Murzello K....Rabies is a neglected tropical zoonotic disease caused by rabies-virus (RV) infection and is responsible for almost 60,000 annual deaths globally, largely affecting the socio-economically disadvantaged population. Although fatality is preventable by immunization either before or after exposure with therapeutic antibodies, the high cost of prophylaxis or treatment limits their accessibility for the affected population. However, due to the almost 100% fatality rate in symptomatic individuals, almost 29 million annual vaccinations are performed, imposing high financial burden. Human transmission ...
Yang Y, Guo K, Xu L, Guo W, Dong M, Liu W, Li S, Zhang Z, Chu X, Wang Y, Zhang Z, Hu Z, Wang X.Equine influenza (EI), caused by the equine influenza virus (EIV), is an acute respiratory disease that has become enzootic worldwide, resulting in frequent outbreaks and substantial economic losses within the equine industry. In this study, we developed a competitive enzyme-linked immunosorbent assay (NP-cELISA) for the detection of antibodies against the EIV nucleoprotein (NP). The assay was designed by coating plates with purified monoclonal antibodies (mAbs) against the NP protein, followed by simultaneous incubation of the test serum samples and HRP-NP antigen in a competitive binding rea...
Davoudi N, Behbahani M, Mohabatkar H, Dini G, Bakhshesh M.Equine herpesvirus type 1 (EHV-1) is a globally prevalent equine pathogen responsible for severe respiratory, neurological, and reproductive disorders. Accurate and ultrasensitive detection of EHV-1 is critical for timely disease management. In this study, we report the development of the first G-quadruplex-forming aptamer specifically designed for EHV-1 detection. The aptamer was generated using an in silico approach, and its G-quadruplex conformation was confirmed using circular dichroism (CD) spectroscopy and crystal violet fluorescence assays. Binding affinity and specificity were assessed...
Aucoin AA, Zhidkov V, Legere RM, Borba KER, Landrock KK, Parker LE, Bray JM, Bordin AI, Cohen ND.To characterize age-related trajectories of the relative concentrations of anti-virulence-associated protein A (VapA) immunoglobulin (Ig)-G1, IgG3/5, IgG4/7, and IgA in serum and bronchoalveolar lavage fluid (BALF) as indicators of systemic and intrapulmonary immune responses in foals naturally exposed to Rhodococcus equi. Unassigned: Blood and BALF samples were collected at ages 4, 14, 28, and 56 days from healthy Quarter Horse foals (n = 19) naturally exposed to R equi. Samples were tested via ELISA for relative concentration of IgG1, IgG3/5, IgG4/7, and IgA recognizing the VapA of R equi. D...
Sadowska A, Molcan T, Słyszewska M, Skarzynski DJ, Ferreira-Dias G, Szóstek-Mioduchowska A.Equine endometrosis is a chronic degenerative condition of the endometrium. A hallmark feature of endometrosis is endometrial fibrosis accompanied by degenerative changes in the adjacent tissue structure. Tumor necrosis factor α (TNFα), a pleiotropic cytokine produced by various immune cells, plays a dual role in coordinating immune responses and regulating cell/tissue homeostasis, making it an important regulator of fibrotic-related disorders. However, the exact role of TNFα in the development of equine endometrial fibrosis remains to be discovered and explained. Therefore, the main aim of...
