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Topic:Antibodies
Antibodies in horses are specialized proteins produced by the immune system in response to foreign substances, known as antigens. These substances can include pathogens such as bacteria, viruses, and parasites. Antibodies function by recognizing and binding to specific antigens, thereby neutralizing them or marking them for destruction by other immune cells. In equine health, antibodies are integral to both natural immune responses and those induced by vaccinations. The study of antibodies in horses encompasses their production, diversity, and role in disease resistance and management. This page gathers peer-reviewed research studies and scholarly articles that explore the generation, function, and implications of antibodies in equine immunology and disease control.
Correction: Development of an indirect ELISA for the detection of venezuelan equine encephalitis virus specific antibodies in horses. [This corrects the article DOI: 10.1371/journal.pone.0338819.].
An atypical extrapulmonary presentation of rhodococcus equi infection in a foal: a case report. Rhodococcus equi infection in foals is primarily associated with pulmonary disease but may also present with extrapulmonary manifestations (Giguère et al. 2011; Reuss et al. 2009). Hemolytic anemia is a rare and poorly described complication, with only a single previous report of presumed immune-mediated hemolytic anemia in foals affected by R. equi. This case report describes the clinical presentation, diagnostic findings, disease progression, and postmortem examination of a 4-month-old Holsteiner foal with confirmed R. equi infection and severe anemia consistent with a presumed immune-media...
No evidence of H5N1 avian influenza virus infection in Japanese horses in 2025. The global spillover of clade 2.3.4.4b H5N1 highly pathogenic avian influenza virus into mammalian hosts has become a concern for public health as well as for the equine industry. However, previous reports on H5N1 natural infection and the presence of specific antibodies in horses remain limited. Therefore, we conducted a serosurveillance study to assess the prevalence of H5N1 antibodies in serum samples collected from 400 horses in Japan. Samples were screened using competitive ELISA (cELISA) and hemagglutination inhibition (HI) tests against H5-recombinant protein and H5N1 viral antigen, res...
Antibody kinetics against tetanus toxoid before and after primary vaccination of foals. Vaccination recommendations for foals against Clostridium tetani vary. Available studies assessing foal immune responses, maternal antibody interference, or individual variation often used small foal numbers. Objective: To quantify antibody responses after tetanus vaccination in foals and explore associations with passively transferred tetanus antibodies. Methods: Longitudinal cohort study. Methods: Sixty-two Warmblood foals from a single stud farm were followed from birth to 360 days of age. Foals received tetanus vaccinations at day 180 (d180) and d220 of life. Serum samples were collected...
Increasing Seroprevalence In Horses Evidences Widespread Circulation Of West Nile Virus In Albania. West Nile virus (WNV) is a zoonotic mosquito-borne flavivirus that causes West Nile disease, an emerging and re-emerging infection of major global importance. Horses are an important sentinel species for monitoring WNV circulation. Since viraemia in horses is brief and viral loads in the blood are low, serological assays are the primary tools used to monitor WNV exposure. This study aimed to estimate the seroprevalence of WNV antibodies in horses in Albania. Between 2017 and 2020, 509 serum samples were collected from apparently healthy, unvaccinated horses across different regions of the coun...
A Leptospirosis Outbreak in a Riding Stable in Central Italy. Leptospirosis is a widespread zoonotic disease of major concern for both veterinary and public health. In horses, it is associated with equine recurrent uveitis, a painful condition that may lead to blindness and affects approximately 10% of the global horse population. In May 2025, following the occurrence of three uveitis cases in a riding stable in Central Italy, 94 equine blood samples were collected and tested using the microscopic agglutination test (MAT) for spp. Antibody titres against serogroup Icterohaemorrhagiae were detected in 68 horses (72.4%). An on-site investigation was condu...
Development of lateral flow assays for the rapid diagnosis of glanders in equids. Glanders is a contagious zoonotic disease caused by that primarily affects horses, donkeys, and mules. It remains endemic in parts of Asia, Africa, the Middle East, and South America, where increasing case reports highlight the need for accessible diagnostic tools. Conventional diagnostic methods are limited by high costs and specialized laboratory requirements, whereas lateral flow assays (LFAs) offer practical, user-friendly, and rapid alternatives. In this study, we developed three LFAs targeting antibodies against the antigens Hcp1, GroEL, and whole-cell lysate (WCL), previously identifi...
A new single-antigen serological test accurately detects horses infected with Streptococcus equi subsp equi. To develop an accurate serological test for detecting horses infected with Streptococcus equi subsp equi (SEE). Unassigned: The study was designed as a prospective experiment. First, 89 proteins either expressed on the surface or secreted by SEE were cloned, expressed in a cell-free culture system, and printed onto a microarray. Microarrays were probed with serum from 30 horses with strangles, 30 horses with no history of infection or immunization against SEE, and 18 horses infected with Streptococcus equi subsp zooepidemicus (SEZ); serum samples were collected between 2020 and 2021 from Texas...
Influence of collection site on cerebrospinal fluid test results in horses with equine protozoal myeloencephalitis. Cerebrospinal fluid (CSF) analysis is a critical component in the diagnosis of equine protozoal myeloencephalitis (EPM). Test results obtained may differ based on different collection sites. Objective: Compare results of EPM-specific diagnostic tests obtained from different collections sites in EPM-affected and non-EPM affected horses. Methods: Twenty control and 7 EPM-affected horses. Methods: Prospective observational study. CSF was collected from the lumbosacral (LS) and cranial sites (atlantooccipital or C1-2) in 27 horses and EPM-specific diagnostic tests were performed. Data were summari...
Humoral immune response to equine mesenchymal stem/stromal cells (MSCs): MHC compatibility has more influence than inflammatory priming or chondrogenic differentiation. Mesenchymal stem/stromal cells (MSCs) hold great potential for treating various conditions, but their effectiveness and safety in allogeneic therapies can be affected by the recipient's immune response, among other factors. Allogeneic MSC administration has been associated with immune recognition in different species, including horses. These animals are both veterinary patients and translational models, offering valuable insights into how allogeneic MSCs interact with the immune system in vivo. Factors such as inflammation, chondrogenic differentiation, and major histocompatibility complex (MH...
Systematic establishment of approaches to the detection of equine macrophage polarization and their application in pathogenic infection. Macrophage phenotypic adaptation critically regulates inflammatory balance during infection; however, progress in equine immunology has been limited by a lack of specific tools for standardized identification. To address this gap, we established a reliable, antibody-based detection method for characterizing equine macrophage M1-like and M2-like marker profiles. After initially validating canonical marker genes via qPCR, we developed specific monoclonal antibodies targeting the differentially expressed surface proteins CD80 (M1-like) and CD163 (M2-like). These novel antibodies enabled the creat...
Tick-borne bacterial and protozoal pathogens in horses in Austria – A cross-sectional study on current and past infections and potential risk factors. Tick-borne bacterial and protozoal pathogens are a major threat to equine health worldwide. In Austria, studies on pathogens such as piroplasms, Anaplasma phagocytophilum and Borrelia spp. in horses are scarce and do not cover the countrywide horse population. To address this, blood samples from horses without prior record of infection with tick-borne pathogens (n = 588) were tested for the presence of Theileria equi, Babesia caballi or A. phagocytophilum DNA by PCR and for specific antibodies against these pathogens and Borrelia burgdorferi with commercially available assays. While no DNA of ...
Cryo-EM structure of African horse sickness virus VP2 receptor-binding protein enables nanoparticle vaccine design. African horse sickness virus (AHSV) is a lethal equine pathogen with no licensed vaccine other than vaccines containing attenuated virus, which pose safety risks. Endemic to sub-Saharan Africa, AHSV has caused epizootics in Spain and Portugal, Cyprus, Morocco, the Middle East, India and Pakistan and, most recently, Thailand. Here, we resolve the 3.11 Å cryo-EM structure of full-length VP2 from AHSV serotype 4, adopting its native triskelion architecture and shedding light on an α-helical domain anchoring the triskelion core, which is absent in other structurally characterized orbiviruses. ...
First evidence of exposure to West Nile Virus in horses within Denmark, 2025. A nationwide serological screening of 822 horses was conducted in Autumn 2025 to investigate potential exposure to West Nile Virus (WNV) within Denmark. Serum samples were tested for antibodies against WNV, tick-borne encephalitis virus (TBEV) and Usutu virus (USUV). Four horses without any history of travel outside of Denmark, or previous vaccination against WNV, tested positive for WNV neutralising antibodies. The results support local exposure to WNV indicating that virus infected mosquitoes have been present in Denmark and underline the usefulness of horses as sentinels for the risk of hum...
Development of an indirect ELISA for the detection of venezuelan equine encephalitis virus specific antibodies in horses. Venezuelan equine encephalitis virus (VEEV) is a re-emerging zoonotic pathogen to which equines are most susceptible mammals hosts with a high mortality rate raging from19 to 83%. The virus, transmitted between vertebrates and mosquitos, causes unpredictable sporadic epizootic outbreaks in equids and humans across Central and South America. Although VEEV is not currently circulating in Europe the combination of global change, increasing international trade and the presence of potentially competent vectors (mosquitoes of the genera Aedes and Culex), raises a non-negligible risk of its introduct...
Molecular detection of Toxoplasma gondii in an aborted equine fetus and serological evidence of infection in mares enrolled in embryo transfer programs in Brazil. Toxoplasma gondii infection is widely recognized as an important cause of reproductive losses in goats and sheep. However, the impact of this parasitic infection in mares remains poorly investigated, reflecting the neglect of this pathogen in equine production. The present study aimed to conduct a serological survey in 100 mares from farms enrolled in embryo transfer (ET) programs in Northeastern Brazil, report the first molecular detection of T. gondii in the placenta and aborted fetus of a mare in the country, and evaluate potential risk factors associated with infection. Anti-T. gondii IgG ...
Cross-protective effect of a multicomponent fusion protein vaccine during a natural episode of Streptococcus zooepidemicus respiratory disease in ponies. Streptococcus equi subspecies zooepidemicus is a highly diverse opportunistic pathogen of horses, associated with respiratory disease and endometritis. Objective: To characterise S. zooepidemicus isolates recovered from young ponies during a natural episode of respiratory disease, and to determine if vaccination with Strangvac®, a vaccine against Streptococcus equi subspecies equi, conferred cross-protection. Methods: Retrospective analysis of a double-blinded placebo-controlled study involving 32 ponies (16 vaccinates and 16 placebo controls) that experienced a natural episode of respiratory...
Seroprevalence of Orthoflaviviruses in horses in 3 different Algerian climatic zones between 2021 and 2023. Orthoflaviviruses are etiological agents of neurological diseases in equines. Horses are susceptible to equine Tick-borne encephalitis virus (TBEV), Usutu virus (USUV), and West Nile virus (WNV), although mostly WNV has been associated with clinical disease. The aim of the present study was to estimate the prevalence of TBEV, USUV and WNV in 289 healthy horses from nine provinces of Algeria. This study was conducted between March 2021 and December 2023. Sera that tested positive, doubtful, or negative close to the doubtful threshold in the Orthoflavivirus-ELISA were further tested by the virus...
Identification of gene conversion events in horse IGHV suggests preferential hotspots for diversification. The humoral immune response relies on a diverse antibody repertoire, which is expanded through processes such as somatic hypermutation, class-switch recombination and gene conversion. These processes are primarily mediated by activation-induced cytidine deaminase (AID). Gene conversion generates diversity in immunoglobulin heavy and light chains (IGHVs) in species such as chickens and rabbits, though it has not been widely studied. Since 80% of the equine IGHV repertoire originates from only three functional gene segments, we examined gene conversion events in horses to assess their role in an...
Immunization of Foals with Equine Rotavirus A Vaccine Can Stabilize or Increase Rotavirus-Specific Neutralizing Antibody Titers. Despite a monovalent G3P[12] ('G3') vaccine being available for horses, equine rotavirus A (ERVA) is still the predominant infectious pathogen causing diarrhea in foals in the United States of America (U.S.). Previous research has shown that maternal neutralizing antibody (NAb) titers are too high and will interfere with the vaccination of foals at 30 and 45 days of age. We aimed to determine if it is possible to increase NAb titers in foals through vaccination before they are vulnerable to ERVA infection. We immunized two foals with the commercially available vaccine (G3) at solely three mont...
A synergistic dual-endopeptidase platform for high-yield, homogeneous F(ab’)2 production from polyclonal equine immunoglobulins for therapeutic applications. Therapeutic F(ab') fragments derived from polyclonal equine antisera remain essential emergency biologics for addressing snake envenomation, tetanus, and viral infections. Traditional production methods rely on pepsin digestion, which is limited by non-specific proteolysis, harsh acidic conditions (pH 2.0-4.0), risk of contamination from animal sources, and significant batch variability, often complicating downstream preparative separations. In this study, we introduce a synergistic dual-endopeptidase platform that integrates hinge-specific biocatalysis with affinity chromatography to facilit...
Integrated workflow for production and in vitro characterization of equine anti-SARS-CoV-2 hyperimmune serum with epitope mapping. This study establishes an integrated workflow linking antibody production, neutralization assessment, and epitope mapping, supporting the identification of antigenic regions recognized by polyclonal antibodies generated in vivo. The viral suspension was inactivated with β-propiolactone under biosafety level 3 (BSL-3) conditions, with no cytopathic effect or plaque formation observed, confirming loss of viral replicative capacity. The produced immunogen retained antigenic activity, as demonstrated by reactivity with IgG antibodies from vaccinated and previously infected individuals. Protein an...
Evaluation of synthetic peptides derived from glycoproteins gp45 and gp90 as candidates for the immunodiagnosis of equine infectious anemia. The international scientific community continues to promote the development of diagnostic techniques with improved performance and novel capture antigens. On this basis, two synthetic peptides derived from gp45 and gp90 were evaluated to identify the best candidate for the indirect immunodetection of infection. In both assays, 68 serum samples from naturally infected horses in Granma Province (59 seropositive and 9 seronegative), previously classified using the agar gel immunodiffusion (AGID) test, were analyzed. The diagnostic performance of each candidate peptide was assessed by calculating ...
Inter-individual variability in equine antibody responses to African snake venoms follows heavy-tailed distributions with implications for antivenom production. Variability in the antibody response of horses used for snake antivenom manufacture is well recognized, yet its statistical structure and implications for industrial productivity remain poorly characterized. In this study, we quantified antivenom antibody titers by ELISA in a cohort of 14 horses immunized with venoms from the clinically most important snakes in sub-Saharan Africa. To integrate antibody levels with plasma availability, we calculated the Cumulative Plasma Productivity (CPP) by converting individual plasma volumes into titer-corrected equivalents and sequentially pooling these vo...
Equine sentinels and one health: a comprehensive serological survey of Crimean-Congo hemorrhagic fever virus in southeastern and Central Europe. Crimean-Congo hemorrhagic fever (CCHF) is the widespread tick-borne viral disease affecting humans with endemic circulation across Africa, Asia, Eastern and Southern Europe. Climate change, global travel, and animal trade have accelerated the expansion of spp., the primary tick vectors of CCHF, into previously non-endemic areas, including the Czech Republic. To assess the current distribution of CCHF in equids across Southeastern and Central Europe, we screened serum samples from horses and donkeys from Bulgaria ( = 579), Romania ( = 1,534), and the Czech Republic ( = 576) by the ...
Multivalent Disabled Infectious Single Animal (DISA)-DIVA vaccine for all nine serotypes of African horse sickness virus (AHSV) is broadly protective in IFNAR (-/-) mice. African horse sickness (AHS) is a highly severe, midge-borne disease of equids showing a mortality rate of > 90% in naive domestic horses. Outbreaks are caused by AHS virus (AHSV) and result in devastating economic losses in developing countries as equids play a crucial role in the agricultural industry and many households. The AHSV species encompasses nine serotypes showing no or limited cross protection, which is challenging regarding AHS vaccine development. Recently, and like bluetongue virus (BTV), the AHS Disabled Infectious Single Animal (DISA)-DIVA vaccine platform was developed...
Crimean-Congo Haemorrhagic Fever Virus Exposure in Horses and Donkeys in Border Livestock Markets of Nigeria. Crimean-Congo haemorrhagic fever virus (CCHFV) is a tick-borne zoonotic pathogen of major public health importance in Africa. Although CCHFV exposure has been reported in several livestock species in Nigeria, data on equids remain limited despite their extensive involvement in livestock movement and trade. This study assessed CCHFV seroprevalence in horses and donkeys in major international livestock markets in northern Nigeria and examined factors associated with exposure. Methods: From June 2023 to July 2024, a longitudinal sero-surveillance study was conducted in three high-volume livestock...
Seroprevalence of Sarcocystis neurona and Neospora hughesi in healthy horses from the province of Alberta, Canada. Literature on the seroprevalence of antibodies to the causative agents of equine protozoal myeloencephalitis (EPM) in Canada is limited. Objective: To determine the prevalence of serum antibodies against Sarcocystis neurona and Neospora hughesi in apparently healthy horses without signs of neurologic disease which have always resided in Alberta, Canada, using commercially available immunodiagnostic tests. Methods: Samples from 116 healthy horses were obtained from a biobank containing horse serum collected across Alberta in 2021 and 2022. Samples were selected based on owner survey responses, ...
Development and evaluation of an enzyme-linked immunosorbent assay for measuring antibodies against VP8∗ receptor binding domain of equine rotavirus A. Equine rotavirus A (ERVA) poses a significant threat to foal health, necessitating reliable serological tools for assessing protective immune responses. This study focused on the development of an enzyme-linked immunosorbent assay (ELISA) for the measurement of antibodies against the VP8∗ receptor binding core domain of ERVA. Following the expression and purification of VP8∗ receptor binding domain from the bacterial expression system, the ELISA for detecting anti-ERVA VP8∗ antibodies with VP8∗ as a coating antigen was developed and its performance was validated by the comparative anal...
In Vitro Characterization of an Equinized Anti-PD-L1 Antibody for Cancer Immunotherapy in Horses. Horses develop spontaneous tumors, typically in old age. Although local tumor control can be achieved using conventional therapies, systemic therapies are required to treat recurrent and/or metastatic tumors. Immune checkpoint inhibitors, such as anti-PD-L1 antibodies, have been approved for the treatment of various tumor types in humans; however, little is known about the immunosuppressive roles of the PD-1/PD-L1 pathway in horses, and the therapeutic potential of these inhibitors remains to be elucidated. Previously, we reported that the rat monoclonal anti-PD-L1 antibody 6C11-3A11 cross-rea...
