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Topic:Virus
The study of viral infections that affect equine species assesses the relationship between viruses and horses. Infections can lead to a range of clinical symptoms and may impact the health and performance of horses. Common equine viruses include Equine Influenza Virus, Equine Herpesvirus, and West Nile Virus, among others. Understanding the mechanisms of viral transmission, pathogenesis, and host immune responses is essential for developing effective prevention and treatment strategies. This page compiles peer-reviewed research studies and scholarly articles that explore the epidemiology, molecular biology, and clinical management of viral infections in horses.
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...
Isolation and Identification of Emerging Equine Encephalosis Virus Serotype 6 in Israel, 2023. Equine encephalosis (EE) is an arthropod-borne viral disease resembling a mild form of African horse sickness disease, which affects all species of equids. Previously, only EEV serotype 4 (EEV-4) caused sporadic outbreaks of the disease in Israel. In the summer of 2023, EE was clinically diagnosed in horses and donkeys in Israel. For laboratory confirmation, tissue cultures were inoculated with whole-blood samples obtained from sick animals. Five EEV isolates were successfully recovered in tissue and confirmed by conventional RT-PCR and Sanger sequencing of several viral genes. BLAST analysis ...
An epizootic of equine viral arteritis at a Thoroughbred racetrack in Illinois: 223 cases. An epizootic of equine viral arteritis (EVA) occurred over an 8-wk period in the summer of 1993 at a midwestern Thoroughbred (TB) racetrack that ceased operations in 2021. Based on clinical signs, viral isolation, and serology, 223 horses (213 TBs, 10 lead ponies) were affected. Consistent clinical signs included fever (38.3-40.6°C; 101-105°F), depression, inappetence, and diffuse urticaria, including distal limb and preputial edema. Equine arteritis virus (EAV) was cultured from buffy coat samples from 24 of 28 acutely ill horses. Seventeen of 18 convalescent horses and 1 of 92 non-affected...
Equine infectious anemia virus blocks interferon responses through Rev-mediated activation of the stress granule-PKR-eIF2α pathway. Type I interferons (IFNs) play a pivotal role in antiviral defence by inducing interferon-stimulated genes (ISGs) that target multiple stages of viral replication. Equine infectious anemia virus (EIAV) is an ancient lentivirus that establishes long-term asymptomatic infections in equids, suggesting its exceptional immune evasion capabilities. However, the mechanisms by which EIAV modulates IFN responses remain unclear. Here, we demonstrate that EIAV infection attenuates ISG expression at the post-transcriptional level. The viral Rev protein plays a central role by interacting with the stress g...
Equine arteritis virus Nsp10 promotes MAVS proteasomal degradation via E3 ligases Smurf1/MARCH5. Equine arteritis virus (EAV) is a positive-sense, single-stranded RNA virus that belongs to the family , which also includes porcine reproductive and respiratory syndrome virus (PRRSV). EAV is the causative agent of equine viral arteritis (EVA), an economically important systemic, reproductive, and respiratory disease of equids. EAV infection triggers host innate immunity, yet the precise strategies employed by the virus to evade immune defenses and achieve productive infection are poorly characterized. In this study, it was observed that EAV infection can induce a cellular IFN response; howev...
Possible Effects of C-Reactive Protein in the Central Nervous System During Venezuelan Equine Encephalitis Virus Infection. Venezuelan equine encephalitis virus (VEEV) is an alphavirus vectored by mosquitos. It can cause disease in equines and humans characterised by a febrile illness that may progress into encephalitis. Replication of VEEV in the central nervous system induces activation of glial cells and neurons, compromising the blood-brain barrier (BBB) and inducing a state of neuroinflammation. This inflammation can lead to symptoms such as confusion, seizures, and coma, and sustained inflammation contributes to neurodegeneration. C-reactive protein (CRP) is a biomarker that has previously been associated wit...
CXCL16-associated genetic susceptibility to equine viral arteritis in export-bound horses from Spain. Equine viral arteritis (EVA) remains a relevant health and economic concern due to the ability of some infected stallions to establish long-term persistent infection with equine arteritis virus (EAV). Allelic variation in the CXCL16 gene has been identified as a determinant of susceptibility or resistance to the carrier state, positioning genotyping as a useful tool for risk-based reproductive and health management. Objective: To characterise the distribution of CXCL16 genotypes in export-bound horses from Spain and to assess the utility of CXCL16 genotyping for EVA prevention and control. Met...
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...
Molecular prevalence of equine parvovirus hepatitis in healthy horses from the Northern region of the state of Rio Grande do Sul, Brazil. The equine parvovirus hepatitis (EqPV-H) was initially linked to fatal cases of equine serum hepatitis but, more recently, it has also been detected in sick or asymptomatic horses around the world, including in a limited number of horses in southeastern Brazil. In this study we aimed to assess the prevalence of EqPV-H DNA in the serum of healthy horses in the northern region of Rio Grande do Sul state, Brazil. For this purpose, we used 1000 serum samples collected from horses from 40 municipalities and organized them into 200 pools of five samples each, based on origin and age. Using a nested ...
Insights from healthy mares reveal that mammalian uteri harbor a diverse virome. The Earth's estimated 10 virions, primarily phages, significantly impact microbial ecosystems. Despite their abundance, viromes remain relatively understudied-particularly in domestic animals. While recent studies have described a dynamic commensal microbiome in mammalian uteri, no research has yet characterized the commensal virome in a mammalian uterus. In this study, we report for the first time the presence of a sparse, but diverse native virome in the equine uterus. The resulting virome database consists of 513 non-redundant viral genomes (> 2 kb). Taxonomic annotations revealed the...
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 ...
Global prevalence and epidemiological determinants of African horse sickness: A systematic review and meta-analysis. African horse sickness (AHS) is a highly fatal, vector-borne viral disease of equids with substantial economic and animal health impacts, particularly in endemic regions. Despite numerous epidemiological studies, reported prevalence estimates remain highly variable, and a comprehensive quantitative synthesis is lacking. This study aimed to systematically evaluate and synthesize the global prevalence of AHS and to identify sources of epidemiological heterogeneity. A systematic review and meta-analysis were conducted following PRISMA 2020 guidelines, with the protocol registered in the Open Scie...
Retrospective assessment of equine herpesvirus type 1 (EHV-1) genotype-associated clinical disease in Ontario. Equine herpesvirus type 1 (EHV-1) is an important viral pathogen in horses, associated with diverse clinical manifestations including fever, upper and lower respiratory disease, neurological signs, ocular disease, and abortion. Currently, EHV-1 variants (genotypes) are classified based on a single nucleotide polymorphism mutation of the open reading frame 30 (ORF30). Unassigned: The aim of this retrospective study was to evaluate the EHV-1 genotypes present in horses with various clinical presentations, including respiratory disease, abortion, and neurological disease, at a referral center in ...
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 ...
Search for Equus caballus papillomavirus type 2 in tissues of asymptomatic horses in southern brazil. Equus caballus papillomavirus type 2 (EcPV-2) has been recently associated with the development of genital squamous cell carcinomas in horses. Nevertheless, its circulation among healthy, asymptomatic horses remains poorly understood. This study aimed to investigate the presence of EcPV-2 DNA in asymptomatic horses submitted to necropsy in southern Brazil. A total of 54 horses without clinical or histological evidence of genital lesions were investigated: 40 necropsied animals and penile mucosa specimens collected from 14 horses at a local abattoir. Tissue samples were subjected to histologica...
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...
Mucosal T cell activation pathways are upregulated by equine herpesvirus type 1 infection. Equine herpesvirus type 1 (EHV-1) is a high morbidity and mortality virus that impacts horse populations worldwide. As a respiratory virus, it enters through the upper respiratory tract (URT), where mucosal immunity plays a crucial role in preventing severe disease. In this study, flow cytometry was used to characterize the nasal leukocyte population during EHV-1 infection, and RNA sequencing of nasal secretions was employed to assess transcriptional markers of the mucosal immune response. Horses with distinct immune statuses were compared at four stages: pre-infection, early (day 1 and 3 post...
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...
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...
Cross-neutralization and antigenic characterization of simian and equine group A rotaviruses. Rotaviral diarrhea in foals is caused by two dominant G3P[12] and G14P[12] genotypes of equine rotavirus A (ERVA). Protection of foals against ERVA infection and disease is achievable by passive antibody transfer through colostrum from mares receiving inactivated monovalent G3P[12] vaccine. Simian rotavirus SA11 G3P[2] is also included in ERVA vaccines to protect foals. Here, we characterized cross-neutralization and protection among three distinctive rotaviruses carrying the same or different G (defined by VP7) or P (defined by VP4) genotype by using a rabbit and equine monospecific antisera ...
Global seroprevalence and epidemiological patterns of equine viral arteritis from 1968 to 2025: A systematic review and meta-analysis. Equine viral arteritis (EVA) is a globally widespread infectious disease affecting equids, with significant consequences for reproductive efficiency and the regulation of international equine trade. Nevertheless, despite the accumulation of numerous region-specific investigations, an integrated synthesis of global seroprevalence estimates and overarching epidemiological patterns remains insufficiently developed. Objective: To calculate the pooled global seroprevalence of EVA and to explore sources of epidemiological heterogeneity. Methods: A systematic review and meta-analysis were undertaken ...
Diagnosis and Surveillance of West Nile Virus Infection in Horses: Current Methods, Challenges, and Future Directions. West Nile virus (WNV) is a mosquito-borne flavivirus of growing importance for both human and equine health in Europe. Horses are highly susceptible to neurological disease and, because they share ecological exposure with humans, they represent valuable sentinels for detecting local viral circulation within a One Health framework. However, diagnosis of WNV infection in equines is complicated by the short and low-level viraemia, which limits the sensitivity of molecular assays, and by serological cross-reactivity with related flaviviruses and the confounding effects of vaccination. In this narr...
Nucleolar proteins nucleolin and nucleophosmin 1 differentially relocalize during equid alphaherpesvirus 1 (EHV1) infection. We investigated equine nucleolar proteins nucleophosmin 1 (NPM1) and nucleolin (NCL) during EHV1 infection to develop understanding of EHV1-nucleolar interactions. Equine NPM1 primarily localized throughout nucleoli whereas NCL accumulated in a peri-nucleolar ring and localized throughout the nucleoplasm. EHV1 did not notably affect NPM1 or NCL protein levels but did alter their subnuclear localization. NPM1 accumulated in EHV1 replication compartments and remained nucleolus-associated until very late infection stages, characterized by a kidney bean-shaped nucleus and round cell morphology. NC...
Equine genital and ocular squamous cell carcinomas: clinical, histopathological, molecular and viral characterization with proposed histopathological classification system. Equine squamous cell carcinomas (eSCCs) are common, and a proportion are likely induced by papillomavirus 2 (EcPV-2). Accurate prediction of clinical outcomes is challenging with no recognized prognostic criteria or consistent histopathological classification scheme for eSCC. The aims of this study were to histopathologically subtype a large case series of eSCCs (genital and ocular) and correlate them with p16 and HER-2 expression, equine papillomavirus infection status, and various clinical and histopathological parameters to predict tumour behavior and prognosis. One hundred and eighty-five...
Culicoides biting midges (Diptera: Ceratopogonidae) feeding on donkeys in the United Kingdom, with reference to the risk of transmission and persistence of African horse sickness virus. African horse sickness virus (AHSV: Sedoreoviridae; Orbivirus) causes a severe and often fatal disease in horses (African horse sickness: AHS) and is transmitted almost exclusively by Culicoides biting midges (Diptera: Ceratopogonidae). In recent years, unprecedented outbreaks of AHSV have occurred in new geographical foci in Thailand and other related Culicoides-borne viruses continue to emerge unexpectedly, causing disease outbreaks in northern Europe. This study investigated Culicoides abundance and diversity at a donkey (Equus asinus) sanctuary in southern England. The incidence and severi...
Interstitial pneumonia associated with equid gammaherpesvirus 5 infection in 2 neonatal foals, and a retrospective study in Hokkaido, Japan. Various bacterial and viral pathogens have been identified in cases of interstitial pneumonia in foals within the first month of life. A potential association has been suggested between equid gammaherpesvirus 5 (EqGHV5, equine herpesvirus 5; family , taxon species ) and interstitial pneumonia in foals; however, direct histologic evidence has been limited. We examined 2 neonates-12-d- and 24-d-old-with acute respiratory distress and poor response to treatment. Postmortem examination revealed interstitial pneumonia with diffuse alveolar damage and intranuclear inclusion bodies in alveolar macrop...
Orthoflavivirus-associated neurological disease in a UK horse. Keesjan Cornelisse and Andra-Maria Ionescu discuss the clinical presentation, investigation and diagnostic approach to a case of orthoflavivirus infection in a horse in south-west England.
Topical treatment of equine aural plaques with nitric acid and zinc solution. Equine aural plaque caused by equine papilloma viruses is common worldwide and affected horses can show severe clinical signs. Due to its viral aetiology, in some countries affected horses are not allowed to compete. Since lesions persist, showing no spontaneous regression, effective and safe treatment is required. Currently, the only treatment with consistent efficacy is imiquimod. Treatment time is prolonged and adverse effects are common. In humans, papilloma warts are successfully and safely treated with topical nitric-zinc complex solutions inducing a painless caustic effect. Objective: T...
West Nile Virus in Europe: Epidemiology, Vector Ecology, Environmental Drivers, and the Role of Equine Sentinel Surveillance in a One Health Framework. West Nile virus (WNV) is a mosquito-borne flavivirus that remains an important public and veterinary health concern across Europe. Periodic outbreaks affecting humans, horses, and wildlife highlight the complex ecological interactions underlying viral circulation. This narrative review aims to synthesize current knowledge regarding WNV epidemiology, transmission dynamics, and surveillance strategies in Europe, with particular attention to the Romanian context. Available surveillance data indicate recurrent seasonal transmission in several European regions; however, reported case numbers may be...
Computational modelling of the equine arteritis virus GP5/M Dimer: Implications for immune evasion and virulence. 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...
