Equine Herpesvirus (EHV) is a contagious virus that affects horses, causing a range of clinical conditions. It primarily impacts the respiratory system but can also lead to neurological disorders, abortion in pregnant mares, and neonatal foal death. The virus is transmitted through direct contact with infected horses or through contaminated surfaces and equipment. There are several strains of EHV, with Equine Herpesvirus-1 (EHV-1) and Equine Herpesvirus-4 (EHV-4) being the most commonly studied due to their prevalence and impact on equine health. EHV-1 is associated with more severe outcomes, including equine herpesvirus myeloencephalopathy (EHM). This page aggregates peer-reviewed research studies and scholarly articles that explore the epidemiology, pathogenesis, clinical manifestations, and management strategies related to Equine Herpesvirus in horses.
Drebert Z, Golke A, Cymerys J, Słońska A, Chmielewska A, Tucholska A, Bańbura MW.Equid herpesvirus type 1 (EHV-1) is a prevalent causative agent of equine diseases worldwide. After primary replication in the respiratory epithelium the virus disseminates systemically through a peripheral blood mononuclear cell (PBMC)-associated viraemia. EHV-1 is the only alphaherpes- virus known so far which is capable of establishing latent infection not only in neurons but also in immune system cells (mainly in lymphocytes and macrophages). Since leukocytes are not the target cells for viral replication but are used to transport EHV-1 to the internal organs, the questionremains how the v...
Stokol T, Yeo WM, Burnett D, DeAngelis N, Huang T, Osterrieder N, Catalfamo J.Equid herpesvirus type 1 (EHV-1) causes outbreaks of abortion and neurological disease in horses. One of the main causes of these clinical syndromes is thrombosis in placental and spinal cord vessels, however the mechanism for thrombus formation is unknown. Platelets form part of the thrombus and amplify and propagate thrombin generation. Here, we tested the hypothesis that EHV-1 activates platelets. We found that two EHV-1 strains, RacL11 and Ab4 at 0.5 or higher plaque forming unit/cell, activate platelets within 10 minutes, causing α-granule secretion (surface P-selectin expression) and pl...
Nielsen MK, Rubinson EF, Chambers TM, Horohov DW, Wagner B, Betancourt A, Reedy SE, Jacobsen S.Anthelmintics and vaccines are commonly given concurrently in routine equine management, but it is unknown to what extent an interaction between the two exists. Cyathostomins can modulate the local immune response by stimulating a type 2 helper T cell (Th2) response. In addition, anti-inflammatory effects of ivermectin have been found in rodent models. It is unknown whether these anti-inflammatory effects affect the acute phase response elicited by commonly used vaccines. This study evaluated how the acute phase inflammatory response, leukocyte expression of pro-inflammatory cytokines, and vac...
Gilkerson JR, Bailey KE, Diaz-Méndez A, Hartley CA.Many viral agents have been associated with respiratory disease of the horse. The most important viral causes of respiratory disease in horses are equine influenza and the equine alphaherpesviruses. Agents such as equine viral arteritis virus, African horse sickness virus, and Hendra virus establish systemic infections. Clinical signs of disease resulting from infection with these agents can manifest as respiratory disease, but the respiratory tract is not the major body system affected by these viruses. Treatment of viral respiratory disease is generally limited to supportive therapies, where...
Dunowska M, Gopakumar G, Perrott MR, Kendall AT, Waropastrakul S, Hartley CA, Carslake HB.Infection with equid herpesvirus 1 (EHV-1) may be asymptomatic, or may result in respiratory disease, abortion, neonatal death, or neurological disease. The aim of this study was to estimate the prevalence of EHV-1 infection, including differentiation between genotypes with aspartic acid (D) and asparagine (N) at position 752 of the DNA polymerase sequence, within a selected population of New Zealand horses. The second aim was to determine the predictive value of serology for detection of latently infected horses. Retropharyngeal lymph nodes (RLN) and trigeminal ganglia (TG) were dissected fro...
Hollingsworth SR, Pusterla N, Kass PH, Good KL, Brault SA, Maggs DJ.To determine the role of equine herpesvirus (EHV) in idiopathic keratoconjunctivitis in horses and to determine whether sample collection method affects detection of EHV DNA by quantitative polymerase chain reaction (qPCR). Methods: Twelve horses with idiopathic keratoconjunctivitis and six horses without signs of ophthalmic disease. Methods: Conjunctival swabs, corneal scrapings, and conjunctival biopsies were collected from 18 horses: 12 clinical cases with idiopathic keratoconjunctivitis and six euthanized controls. In horses with both eyes involved, the samples were taken from the eye judg...
Estell KE, Dawson DR, Magdesian KG, Swain E, Laing ST, Siso S, Mapes S, Pusterla N.Data associating quantitative viral load with severity, clinical signs and survival in equine herpesvirus-1 myeloencephalopathy (EHM) have not been reported. Objective: To report the clinical signs, treatment, and temporal progression of viral loads in 7 horses with naturally occurring EHM and to examine the association of these factors with survival. Methods: Retrospective case series. Methods: The population included 7 horses with EHM presented to the University of California, Davis William R. Pritchard Veterinary Medical Teaching Hospital from May to September 2011. Horses were graded using...
Davis EG, Bello NM, Bryan AJ, Hankins K, Wilkerson M.Protection from infectious disease requires antigen-specific immunity. In foals, most vaccine protocols are delayed until 6 months to avoid maternal antibody interference. Susceptibility to disease may exist prior to administration of vaccination at age 4-6 months. Objective: The aim of this investigation was to characterise immune activation among healthy foals in response to a multivalent vaccine protocol and compare immune responses when foals were vaccinated at age either 90 or 180 days. Methods: Randomised block design. Methods: Twelve healthy foals with colostral transfer were blocked fo...
Claessen C, Favoreel H, Ma G, Osterrieder N, De Schauwer C, Piepers S, Van de Walle GR.Equid herpesvirus 1 (EHV1) is an ubiquitous alphaherpesvirus that can cause respiratory disease, abortion and central nervous disorders. EHV1 is known to infect a variety of different cell types in vitro, but its tropism for cultured primary equine mesenchymal stem cells (MSC) has never been explored. We report that equine MSC were highly permissive for EHV1 and supported lytic replication of the virus in vitro. Interestingly, we observed that an infection of MSC with EHV1 resulted in a consistent downregulation of cell surface molecules CD29 (β1-integrin), CD105 (endoglin), major histocompat...
Equine influenza in England and Scotland, Significant numbers of outbreaks of equine herpesvirus 1 neurological disease in the USA, Summary of surveillance testing, April to June 2014. These are among matters discussed in the most recent quarterly equine disease surveillance report, prepared by Defra, the Animal Health Trust and the British Equine Veterinary Association.
Jiménez D, Romero-Zuñiga JJ, Dolz G.Blood samples from 181 equines from the Central Valley of Costa Rica were collected in the year 2012 to determine the presence of antibodies against selected infectious agents in horses and to determine the risk factors associated with these agents. The presence of antibodies against Equine Infectious Anemia Virus (EIAV), Equine Herpes Virus 1 and 4 (EHV-1 and EHV-4), West Nile Virus (WNV), Influenza A Virus (IAV), Equine Viral Arteritis Virus (EVAV), Babesia caballi, Theileria equi, Neospora caninum and Chlamydia abortus was determined using commercial assays, and risk factors associated with...
Andoh K, Hattori S, Mahmoud HY, Takasugi M, Shimoda H, Bannai H, Tsujimura K, Matsumura T, Kondo T, Kirisawa R, Mochizuki M, Maeda K.Equine herpesvirus type 1 (EHV-1) has haemagglutination (HA) activity toward equine red blood cells (RBCs), but the identity of its haemagglutinin is unknown. To identify the haemagglutinin of EHV-1, the major glycoproteins of EHV-1 were expressed in 293T cells, and the cells or cell lysates were mixed with equine RBCs. The results showed that only EHV-1 glycoprotein C (gC)-producing cells adsorbed equine RBCs, and that the lysate of EHV-1 gC-expressing cells agglutinated equine RBCs. EHV-1 lacking gC did not show HA activity. HA activity was inhibited by monoclonal antibodies (MAbs) specific ...
Marenzoni ML, Sforna M, Stefanetti V, Casagrande Proietti P, Brignone L, Del Sero A, Falcioni F, Orvieto S, Tamantini C, Tiburzi A, Valentini S....In recent years, there has been increasing evidence of the potential pathogenic significance of equine gammaherpesviruses in the horse. In humans, cattle and mice, gammaherpesviruses have already been associated with uterine infection. The aim of the present study was to investigate the presence of gammaherpesviruses in uterine flushings of mares with reproductive problems and to evaluate if there was a possible statistical association with clinical and laboratory findings in these cases. A total of 80 uterine flushings were collected from 61 mares with different reproductive problems and thes...
Baghi HB, Nauwynck HJ.The mucosal surfaces are important sites of entry for a majority of pathogens, and viruses in particular. The migration of antigen presenting cells (APCs) from the apical side of the mucosal epithelium to the lymph node is a key event in the development of mucosal immunity during viral infections. However, the mechanism by which viruses utilize the transmigration of these cells to invade the mucosa is largely unexplored. Here, we establish an ex vivo explant model of monocytic cell transmigration across the nasal mucosal epithelium and lamina propria. Equine nasal mucosal CD172a(+) cells (nmCD...
Pusterla N, Hussey GS.Equine myeloencephalopathy (EHM), an uncommon manifestation of equine herpesvirus 1 (EHV-1) infection, can cause devastating losses on individual farms, boarding stables, veterinary hospitals, and show and racing venues. An improved understanding of EHM has emerged from experimental studies and from data collected during field outbreaks at riding schools, racetracks, horse shows, and veterinary hospitals throughout North America and Europe. These outbreaks have highlighted the contagious nature of EHV-1 and have prompted a reevaluation of diagnostic procedures, treatment modalities, preventati...
Sijmons S, Vissani A, Tordoya MS, Muylkens B, Thiry E, Maes P, Matthijnssens J, Barrandeguy M, Van Ranst M.Equid herpesvirus 3 (EHV-3) is a member of the subfamily Alphaherpesvirinae that causes equine coital exanthema. Here, we report the first complete genome sequence of EHV-3. The 151,601-nt genome encodes 76 distinct genes like other equine alphaherpesviruses, but genetically, EHV-3 is significantly more divergent.
Ons E, Van Brussel L, Lane S, King V, Cullinane A, Kenna R, Lyons P, Hammond TA, Salt J, Raue R.The efficacy of Zylexis®, an immunomodulator in horses based on inactivated Parapoxvirus ovis (iPPVO), was assessed using an equine herpesvirus type 1 (EHV-1) challenge model in the presence of a natural infection with Streptococcus equi equi (S. equi). Eleven horses were treated with iPPVO and twelve were kept as controls. Six horses were challenged with EHV-1 and commingled with the horses on study. Animals were dosed on Days -2, 0 (just before commingling) and Day 7. On Day 11 significantly less nasal discharge, enlarged lymph nodes, EHV-1 shedding and lower rectal temperatures were observ...
Akkutay AZ, Osterrieder N, Damiani A, Tischer BK, Borchers K, Alkan F.Equine herpesvirus type 2 (EHV-2) and EHV-5 are members of the subfamily Gammaherpesvirinae. The viruses are detected in horses with upper respiratory tract disease and are associated with low performance in racehorses. The aim of the current study was to use nested PCR to investigate the epidemiology of EHV-2 and EHV-5 in Arabian horse populations from breeding farms located in three different cities (Eskişehir, Malatya, and Bursa) in Turkey, using a real-time quantitative PCR (qPCR) with a TaqMan® minor-groove-binder (MGB) probe to detect EHV-5. Screening of blood and ocular and nasal swab...
Damiani AM, de Vries M, Reimers G, Winkler S, Osterrieder N.A particularly severe equine herpesvirus type 1 (EHV-1) abortion outbreak occurred at a breeding farm in northern Germany. Sixteen of 25 pregnant mares that had received regular vaccination using an inactivated vaccine aborted and two gave birth to weak non-viable foals in a span of three months, with 89% of cases occurring within 40 days after the initial abortion case. Virological examinations revealed the presence of EHV-1 in all cases of abortion and serological follow-up in mares confirmed recent infection. Molecular studies identified a neuropathogenic variant (Pol/ORF30 A2254 to G2254) ...
Guo X, Izume S, Okada A, Ohya K, Kimura T, Fukushi H.A strain of equine herpesvirus type 1 (EHV-1) was isolated from zebra. This strain, called "zebra-borne EHV-1", was also isolated from an onager and a gazelle in zoological gardens in U.S.A. The full genome sequences of the 3 strains were determined. They shared 99% identities with each other, while they shared 98% and 95% identities with the horse derived EHV-1 and equine herpesvirus type 9, respectively. Sequence data indicated that the EHV-1 isolated from a polar bear in Germany is one of the zebra-borne EHV-1 and not a recombinant virus. These results indicated that zebra-borne EHV-1 is a ...
Miele A, Dhaliwal K, Du Toit N, Murchison JT, Dhaliwal C, Brooks H, Smith SH, Hirani N, Schwarz T, Haslett C, Wallace WA, McGorum BC.Donkey pulmonary fibrosis (DPF) is a spontaneous syndrome of aged donkeys with a high prevalence (35%). No previous detailed characterization of DPF has been performed. We sought to determine the similarities between DPF and recognized patterns of human pulmonary fibrosis. Methods: Whole lungs were collected from 32 aged donkeys at routine necropsy. Gross examination revealed pulmonary fibrosis in 19 donkeys (DPF cases), whereas 13 (control cases) had grossly normal lungs. Eighteen whole inflated ex vivo lungs (11 DPF cases, seven control cases) were imaged with high-resolution CT (HRCT) scan,...
Bannai H, Mae N, Ode H, Nemoto M, Tsujimura K, Yamanaka T, Kondo T, Matsumura T.Equine herpesvirus type 1 (EHV-1) is a major cause of winter pyrexia in racehorses in two training centers (Ritto and Miho) in Japan. Until the epizootic period of 2008-2009, a vaccination program using a killed EHV-1 vaccine targeted only susceptible 3-year-old horses with low antibody levels to EHV-1 antigens. However, because the protective effect was not satisfactory, in 2009-2010 the vaccination program was altered to target all 3-year-old horses. To evaluate the vaccine's efficacy, we investigated the number of horses with pyrexia due to EHV-1 or equine herpesvirus type 4 (EHV-4) infecti...
Kydd JH, Case R, Minke J, Audonnet JC, Wagner B, Antczak DF.Cytotoxic T-lymphocytes (CTLs) are associated with protective immunity against disease caused by equid herpesvirus type 1 (EHV-1). However, the EHV-1 target proteins for CTLs are poorly defined. This limits the development of vaccine candidates designed to stimulate strong CTL immunity. Here, classical CTL assays using lymphocytes from horses of three defined MHC class I types that experienced natural infection with EHV-1 and a modified vaccinia virus construct containing an EHV-1 gene encoding the immediate-early (IE) protein are reported. Horses homozygous for the equine leukocyte antigen (E...
Schulman ML, Becker A, van der Merwe BD, Guthrie AJ, Stout TA.Equine herpesvirus 1 (EHV-1) is one of the most common causes of infectious abortion in mares. Analysing the demography of outbreaks and detailing subsequent reproductive performance of affected mares will assist in the management of future (threatened) epizootics. Objective: To examine the epidemiology and reproductive outcomes of 2 EHV-1 abortion epizootics with very different patterns of morbidity. Methods: Epidemiological and reproductive data were analysed retrospectively following abortion epizootics associated with EHV-1, but initiated via different routes, among unvaccinated mares on 2...
Azab W, Harman R, Miller D, Tallmadge R, Frampton AR, Antczak DF, Osterrieder N.Equid herpesvirus type 1 (EHV-1) was shown to use an unusual receptor for cellular entry - MHC-I molecules. Here, we demonstrated that the closely related EHV, EHV-4, also uses this strategy for cellular invasion, both in equine cells in culture and in the heterologous, non-permissive murine mastocytoma cell line (P815) after stable transfection with horse MHC-I genes. Using a panel of P815 cell lines transfected with individual horse MHC-I genes, we provided support for the hypothesis that EHV-1 and EHV-4 target classical polymorphic MHC-I molecules as viral entry receptors. All known equine ...
Hu Z, Zhu C, Chang H, Guo W, Liu D, Xiang W, Wang X.The objective of this study was to develop a novel EvaGreen (EG) based real-time PCR technique for the simultaneous detection of Equine herpesvirus 1 (EHV-1) and Equine herpesvirus 4 (EHV-4) genomes from equine nasal swabs. Viral genomes were identified based on their specific melting temperatures (T m), which are 88.0 and 84.4 °C for EHV-1 and EHV-4, respectively. The detection limitation of this method was 50 copies/μl or 0.15 pg/μl for EHV-1 and 5 copies/μl or 2.5 fg/μl for EHV-4. This assay was 50-1,000 times more sensitive than the SYBR Green (SG)-based assay using the same primer...
Dunowska M.Equid herpesvirus (EHV) type 1 is a common pathogen of horses with worldwide distribution. Infection with EHV-1 can be subclinical, or can result in sociologically and economically important outcomes such as abortion, neonatal death or neurological disease. The perceived recent increase in the reported cases of EHV-1 neurological disease in the United States of America and Europe over the past decade has caused concerns amongst veterinarians and horse owners worldwide. This review provides an update on the recent developments in our understanding of the pathogenesis and epidemiology of EHV-1 a...
Dunowska M, Hardcastle MR, Tonkin FB.A 10-year-old polo mare presented with a history of weight loss, poor condition and inappetance. Results: The mare was tachycardic, tachypnoeic and febrile. Harsh lung sounds were auscultated over all lung fields. The mare initially responded to treatment with antibiotics, anti-inflammatory drugs and bronchodilators. Throughout the course of treatment, there was a variable lymphocytosis, monocytosis and fluctuation in concentrations of fibrinogen. The mare also developed a mild anaemia, most likely due to chronic disease. Despite treatment, the mare's condition deteriorated over the following ...
Varga J, Fodor L, Rusvai M, Soós I, Makrai L.Two different, inactivated, aluminium salt adsorbed vaccines, one containing a R. equi strain (serotype 1, 10(9) CFU/ml and equine herpesvirus 2 (EHV-2) (1.5 x 10(7) PFU/ml) and another containing R. equi only were used on three studfarms to determine whether the disease can be prevented by vaccination of both pregnant mares and their foals. Pregnant mares received two 3 ml doses of vaccine intramuscularly 6 and 2 weeks before parturition and their foals were vaccinated on two or three occasions at 3, 5 or 7 weeks of age. The efficacy of the vaccines was evaluated on the basis of the clinical ...
Sugahara Y, Matsumura T, Kono Y, Honda E, Kida H, Okazaki K.Heparin extensively inhibited infection of MDBK cells by equine herpesvirus 1 (EHV-1) strains adapted to bovine cells or hamsters, while the reagent merely reduced infectivity of strains passaged only in equine cells. The gC of two strains adapted to non-equine cells seemed to have higher affinity for heparin, although the reagent bound to both the gC and gB of all strains tested. Amino acid substitutions of the gC of the EHV-1 strains adapted to non-equine cells converged on the hydrophilic regions, amino acid residues 92 to 175, resulting in the glycoprotein becoming more cationic. These res...
Edington N, Bridges CG, Griffiths L.When 23 ponies were infected with equid herpesvirus-1 or -4 (EHV-1 or EHV-4), nasal shedding of interferon (IFN) correlated closely with the duration of viral excretion. Equine interferon (EqIFN) was detected in the serum only from animals infected with the EHV-1 virus, and here high levels correlated with clinical symptoms of locomotor disorder and indicated a poor prognosis. Low levels of IFN were detected in explanted mononuclear cells from ponies infected with either virus.
Fortier G, Pronost S, Miszczak F, Fortier C, Léon A, Richard E, Van Erck E, Thiry E, Lekeux P.During a case control study undertaken in 2006-2007, a screening and consensus polymerase chain reaction (PCR) was performed to evaluate the potential role of equid herpesviruses (EHV) in several occurrences of respiratory disorders in 661 horses. Of 785 bronchoalveolar or tracheal lavage fluid samples submitted for analysis, 20 were positive for EHV-5 DNA by sequential analysis of the consensus PCR product. Nineteen of those samples were confirmed using a specific EHV-5 PCR. No particular changes in cytological profile could be associated with the detection of EHV-5 in contrast to suggestions...
Wilson ME, Holz CL, Kopec AK, Dau JJ, Luyendyk JP, Soboll Hussey G.Equine herpesvirus type 1 (EHV-1) is the cause of respiratory disease, abortion storms, and outbreaks of herpesvirus myeloencephalopathy (EHM). Infection of the spinal cord is characterised by multifocal regions of virally infected vascular endothelium, associated with vasculitis, thrombosis and haemorrhage that result in ischaemia and organ dysfunction. However, the mechanism of thrombosis in affected horses is unknown. Objective: To evaluate tissue factor (TF) procoagulant activity and thrombin-antithrombin complex (TAT) levels in horses following infection with EHV-1. Methods: In vitro and ...
Chowdhury SI, Kubin G, Ludwig H.Out of 30 cases of abortion and perinatal deaths in a Lipizzaner stud in Austria 10 mares died after having shown central nervous system disturbances, ataxias and paralysis. The etiological agent of this "abortion storm" was equine herpesvirus type 1 (EHV-1). The restriction enzyme pattern of the DNA from 5 isolates recovered from fetuses has been analyzed and compared with the known reference strains of EHV-1, -2, -4 and an Austrian vaccine strain. The DNA restriction profiles of the Lipizzaner isolates as well as of the vaccine strain could be identified as being typical of abortigenic strai...
Poelaert KCK, Van Cleemput J, Laval K, Descamps S, Favoreel HW, Nauwynck HJ.Short-chain fatty acids (SCFA), such as sodium butyrate (SB), sodium propionate (SPr), and sodium acetate (SAc), are metabolic end-products of the fermentation of dietary fibers. They are linked with multiple beneficial effects on the general mammalian health, based on the sophisticated interplay with the host immune response. Equine herpesvirus 1 (EHV1) is a major pathogen, which primarily replicates in the respiratory epithelium, and disseminates through the body via a cell-associated viremia in leukocytes, even in the presence of neutralizing antibodies. Infected monocytic CD172a cells and ...
Seo MG, Ouh IO, Lee SK, Lee JS, Kwon OD, Kwak D.Respiratory diseases cause significant economic losses (especially in the horse racing industry). The present study describes the detection and genetic characteristics of equine herpesvirus (EHV) from a total of 1497 samples from clinically healthy horses in Korea, including 926 blood samples, 187 lung tissues, and 384 nasal swabs. EHV-2 and EHV-5 were detected in 386 (41.7%; 95% CI: 38.5-44.9) and 201 (21.7%; 95% CI: 19.1-24.4) blood samples, respectively, and in 25 (13.4%; 95% CI: 8.5-18.2) and 35 (18.7%; 95% CI: 13.1-24.3) lung tissues, respectively. EHV-1 and EHV-4 were not detected in eit...
Estell KE, Dawson DR, Magdesian KG, Swain E, Laing ST, Siso S, Mapes S, Pusterla N.Data associating quantitative viral load with severity, clinical signs and survival in equine herpesvirus-1 myeloencephalopathy (EHM) have not been reported. Objective: To report the clinical signs, treatment, and temporal progression of viral loads in 7 horses with naturally occurring EHM and to examine the association of these factors with survival. Methods: Retrospective case series. Methods: The population included 7 horses with EHM presented to the University of California, Davis William R. Pritchard Veterinary Medical Teaching Hospital from May to September 2011. Horses were graded using...
Kydd JH, Hannant D, Mumford JA.This study characterised bronchoalveolar leucocytes collected by lavage from five susceptible and two immune ponies before and after nebulised aerosol infection with equid herpesvirus-1 (EHV-1). Leucocyte counts and lymphocyte phenotypic analyses were performed using either differential staining or an indirect immunofluorescence assay with monoclonal antibodies specific for equine (Eq) CD4, CD5, CD8 and B lymphocytes. After EHV-1 infection, significant changes developed: a transient neutrophilia occurred on Day 2, coincident with a reduction in macrophage numbers and an EqCD5+, EqCD4+ and EqCD...
Laing G, Christley R, Stringer A, Aklilu N, Ashine T, Newton R, Radford A, Pinchbeck G.Pathogens are frequently implicated in equine respiratory disease. In Ethiopia, respiratory disease is a frequent cause for presentation at veterinary clinics and a priority concern for users of working horses. However, there is little existing literature on possible aetiologies. Objective: Determine prevalence of respiratory signs and exposure to major respiratory pathogens through a serological survey. Methods: Cross-sectional. Methods: Systematically selected horses from 19 sites in central Ethiopia were examined clinically and sampled once (August-December 2013). A face-to-face interview c...
van der Meulen KM, Favoreel HW, Pensaert MB, Nauwynck HJ.Equine herpesvirus (EHV)-1 is a pathogen of horses, well known for its ability to induce abortion and nervous system disorders. Clinical signs may occur despite the presence of a virus-specific immune response in the horse. The current review will summarize the research, on how, EHV-1-infected cells can hide from recognition by the immune system. Research findings on immune evasion of EHV-1 will be compared with those of other herpesviruses of veterinary importance.
Balasuriya UB, Lee PA, Tsai YL, Tsai CF, Shen YH, Chang HG, Skillman A, Wang HT, Pronost S, Zhang Y.Equine herpesvirus myeloencephalopathy (EHM), a major problem for the equine industry in the United States, is caused by equine herpesvirus-1 (EHV-1). In addition, EHV-1 is associated with upper respiratory disease, abortion, and chorioretinal lesions in horses. Here we describe the development and evaluation of an inexpensive, user-friendly insulated isothermal PCR (iiPCR) method targeting open reading 30 (ORF30) to detect both neuropathogenic and non-neuropathogenic strains on the field-deployable POCKIT™ device for point-of-need detection of EHV-1. The analytical sensitivity of the EHV-1 ...
Laabassi F, Hue E, Fortier C, Morilland E, Legrand L, Hans A, Pronost S.An episode of acute equine respiratory infection was reported in western Algeria (Tiaret province) between February and March 2011, affecting a large population of horses. Nasal swabs (n=100) were taken from horses aged between 1 and 27 years, presenting with cough and mucopurulent nasal discharge. The prevalence of equine respiratory virus infections was examined using quantitative polymerase chain reaction (qPCR). One, or more, of four equine respiratory viruses were detected in the nasal swabs of 90 of 100 horses (90%) and the detection rate of equine herpesvirus type 1 (EHV-1), equine herp...
Back H, Penell J, Pringle J, Isaksson M, Ronéus N, Treiberg Berndtsson L, Ståhl K.While clinical respiratory disease is considered a main cause of poor performance in horses, the role of subclinical respiratory virus infections is less clear and needs further investigation. Objective: In this descriptive longitudinal study the relationship of markers of subclinical respiratory viral activity to occurrence of poor performance in racing Standardbred trotters was investigated. Methods: 66 elite Standardbred trotters were followed for 13 months by nasal swabs analysed with qPCR for equine influenza virus, equine arteritis virus, equine rhinitis B virus (ERBV), equine herpesvi...
Sijmons S, Vissani A, Tordoya MS, Muylkens B, Thiry E, Maes P, Matthijnssens J, Barrandeguy M, Van Ranst M.Equid herpesvirus 3 (EHV-3) is a member of the subfamily Alphaherpesvirinae that causes equine coital exanthema. Here, we report the first complete genome sequence of EHV-3. The 151,601-nt genome encodes 76 distinct genes like other equine alphaherpesviruses, but genetically, EHV-3 is significantly more divergent.
van der Meulen K, Caij B, Pensaert M, Nauwynck H.In vitro studies demonstrated that most equine herpesvirus 1 (EHV-1)-infected peripheral blood mononuclear cells (PBMC) do not expose viral envelope proteins on their surface. This protects them against antibody-dependent lysis. We examined whether viral envelope proteins are also undetectable on infected PBMC during cell-associated viremia. Further, surface expression of major histocompatibility complex (MHC)-I was examined, since MHC-I assists in making infected cells recognizable for cytotoxic T-lymphocytes (CTL). Four ponies, previously exposed to EHV, and two ponies that had no contact wi...
Browning GF, Studdert MJ.The BamHI, EcoRI, and HindIII physical maps of the genomes of 14 isolates of equine herpesvirus 2 (EHV 2) were determined by Southern blot analysis using DNA fragments of a previously mapped EHV 2 strain 86/67. No two isolates had identical maps for all 3 enzymes, the number of differing cleavage sites between pairs of isolates varying from 3 to 21. Overall 75 cleavage sites were mapped, of which 40 were variable. Cleavage sites occurred throughout the genome, including within the terminal repeat regions. Additionally, fragment length polymorphisms, independent of cleavage site loss or gain, w...
Dutta SK, Myrup AC.A novel, simple method of infectious center assay was developed to detect and quantitate the intracellular existence of equine herpesvirus 1 and equine herpesvirus 2 in peripheral blood mononuclear cells infected in vivo and in vitro with the viruses by cocultivation of these cells with a permissive equine cell culture. The infectious center titers were correlated with the infectious virus titers. In vivo equine herpesvirus 1-infected mononuclear cells obtained from ponies experimentally infected with the virus and equine herpesvirus 2-infected mononuclear cells obtained from selected naturall...
Caterina Termine, Göran Akerström and Gonçalo Paixão of the Fédération Equestre Internationale's Veterinary Department describe the management of an outbreak of neurological equine herpesvirus 1 that affected a number of international showjumping events in Europe earlier this year.
Klouth E, Zablotski Y, Petersen JL, de Bruijn M, Gröndahl G, Müller S, Goehring LS.Equid Herpesvirus Myeloencephalopathy (EHM) is a multifactorial disease following an EHV-1 infection in Equidae. We investigated a total of 589 horses on 13 premises in Europe in search of risk factors for the development of EHM. We found that fever ( < 0.001), increasing age ( = 0.032), and female sex ( = 0.042) were risk factors for EHM in a logistic mixed model. Some breeds had a decreased risk to develop EHM compared to others (Shetland and Welsh ponies; = 0.017; = 0.031), and fewer EHV-1-vaccinated horses were affected by EHM compared to unvaccinated horses ( = 0.02). Data evaluation...
Pusterla N, Wilson WD, Conrad PA, Barr BC, Ferraro GL, Daft BM, Leutenegger CM.This study was designed to determine the relative levels of gene transcription of selected pathogens and cytokines in the brain and spinal cord of 12 horses with equine protozoal myeloencephalitis (EPM), 11 with equine herpesvirus type 1 (EHV-1) myeloencephalopathy, and 12 healthy control horses by applying a real time pcr to the formalin-fixed and paraffin-embedded tissues. Total rna was extracted from each tissue, transcribed to complementary dna (cDNA) and assayed for Sarcocystis neurona, Neospora hughesi, EHV-1, equine GAPDH (housekeeping gene), tumour necrosis factor (TNF)-alpha, interfer...
Snyder DB, Myrup AC, Dutta SK.Pony foals, negative for detectable serum-neutralizing antibody to equine herpesvirus 1 by the standard tube-culture virus neutralization test, were experimentally infected with equine herpesvirus 1. Complement-requiring (CR) and non-complement-requiring (NCR) serum-neutralizing antibodies were evaluated in preinfection and postinfection sera by means of a complement-enhanced plaque reduction assay. Low levels of CR antibodies were found in the preinfection sera of only group II ponies. Upon infection, CR antibodies were detected by day 2 postinfection and reached peak titers between 7 and 14 ...
Andoh K, Takasugi M, Mahmoud HY, Hattori S, Terada Y, Noguchi K, Shimoda H, Bannai H, Tsujimura K, Matsumura T, Kondo T, Maeda K.A major immunogenic region of equine herpesvirus (EHV)-1 glycoprotein E (gE) was identified. Firstly, the various fragments of EHV-1 gE were expressed as fusion proteins with glutathione S-transferase (GST) in Escherichia coli and their antigenicities were compared by immunoblot analysis using sera from horses experimentally infected with EHV-1. Thirty-three amino acids of gE (a.a. 169-201) specifically and sensitively reacted with the antibodies induced by EHV-1 but not EHV-4 infection. The corresponding region of EHV-4 gE (a.a. 169-199) did not react with antibodies to EHV-1, indicating that...
Couetil L, Ivester K, Barnum S, Pusterla N.Equine asthma is a common cause of poor performance in racehorses but it is unclear if respiratory viruses contribute to its etiology. The objective of the study was to determine if respiratory viruses were associated with clinical signs and bronchoalveolar lavage fluid (BALF) cytology in Thoroughbred racehorses. Equine herpesviruses (EHV-1, 2, 4, 5) and equine rhinitis A and B viruses (ERBV, ERAV) genomes were quantified by qPCR in nasopharyngeal, tracheal, and BALF samples collected after racing. The relationships between virus detection and load and clinical signs, performance, BALF cytolog...
Van Cleemput J, Poelaert KCK, Laval K, Van den Broeck W, Nauwynck HJ.The horse's respiratory tract daily encounters a plethora of respirable hazards including air pollutants, mycotoxins and airborne pathogens. To date, the precise effect of air pollution and mycotoxins on respiratory epithelial integrity and subsequent pathogen invasion in the horse has not been studied. Here, diesel exhaust particles (DEP) and three major mycotoxins (deoxynivalenol [DON], aflatoxin B1 [AFB1] and fumonisin B1 [FB1]) were applied to the apical surfaces of both ex vivo respiratory mucosal explants and in vitro primary equine respiratory epithelial cells (EREC) cultivated at the a...
Dinter Z, Klingeborn B.Six cases of paresis occurred in a Swedish stud with 48 mares and a stallion. Complement-fixation tests revealed a recent infection with EHV-1 in most horses of the stud. Serumneutralisation tests showed rapid antibody-titre increases during the course of the disease. This type of antibody response was interpreted as induced by reinfection or, possibly, recurrent infection. Two diseased mares were sacrificed. No virus could be isolated from their central nervous system (CNS), liver or spleen, but there is a presumptive evidence for the presence of an antigen specific to EHV-1 in the CNS and li...
Aleman M, Pickles KJ, Simonek G, Madigan JE.Trigeminal neuralgia or neuropathic pain has been regarded as a putative cause of idiopathic headshaking in horses. Equine herpesvirus-1 (EHV-1) infection and resultant postherpetic pain have been suggested as a possible cause of such neuropathic pain. Objective: To determine the presence of EHV-1 in the trigeminal ganglia of horses with idiopathic headshaking. Methods: Nineteen horses: control (n = 11, 9 geldings, 2 mares, median age 11 years) and headshaking (n = 8, all geldings, median age 11.5 years) horses were sourced from the equine research herd and caseload at the Veterinary Medical T...
Baumann S, Gurtner C, Marti H, Borel N.Species of genus are important pathogens of animals, with a worldwide distribution and broad host range. Some species, such as , also pose a zoonotic disease risk. Abortion is one of the many diseases that has been associated with chlamydial infections in animals, with most attention focused on the economic impacts to sheep production. The role of chlamydia in equine abortions is unknown. Using the family-specific 23S ribosomal RNA (rRNA) real-time PCR, we tested 169 formalin-fixed, paraffin-embedded fetal membrane samples from 162 equine abortion cases collected between 2000 and 2018 in Swi...
