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.
Spence KL, O'Sullivan TL, Poljak Z, Greer AL.Identifying the contact structure within a population of horses attending a competition is an important element towards understanding the potential for the spread of equine pathogens as the horses subsequently travel from location to location. However, there is limited information in Ontario, Canada to quantify contact patterns of horses. The objective of this study was to describe the network of potential contacts associated with an equestrian show to determine how this network structure may influence potential disease transmission. Results: This was a descriptive study of horses attending an...
Torgeman A, Mador N, Dorozko M, Lifshitz A, Eschar N, White MD, Wolf DG, Epstein E.Assuring viral safety of horse plasma-derived products is fundamental for ethical and regulatory reasons. We previously demonstrated the ability of pepsin digestion at low pH to inactivate West Nile and Sindbis viruses in horse plasma. The present study further examined the efficiency of pepsin digestion to inactivate four additional viruses: HSV-1 and BVDV (lipid-enveloped), BPV and Reo-3 (nonenveloped). These viruses were spiked into hyperimmunized horse plasma against botulinum toxin and subjected to low pH (3.2) alone or combined with pepsin digestion (1200 units/ml). Peptic digestion inac...
Zarski LM, High EA, Nelli RK, Bolin SR, Williams KJ, Hussey G.Equine herpesvirus 5 (EHV-5) infection is associated with pulmonary fibrosis in horses, but further studies on EHV-5 persistence in equine cells are needed to fully understand viral and host contributions to disease pathogenesis. Our aim was to develop a quantitative PCR (qPCR) assay to measure EHV-5 viral copy number in equine cell cultures, blood lymphocytes, and nasal swabs of horses. Furthermore, we used a recently developed equine primary respiratory cell culture system to study EHV-5 pathogenesis at the respiratory tract. PCR primers and a probe were designed to target gene E11 of the EH...
Dayaram A, Franz M, Schattschneider A, Damiani AM, Bischofberger S, Osterrieder N, Greenwood AD.For viruses to utilize environmental vectors (hard surfaces, soil, water) for transmission, physical and chemical stability is a prerequisite. There are many factors including pH, salinity, temperature, and turbidity that are known to contribute to the ability of viruses to persist in water. Equine herpesvirus type-1 (EHV-1) is a pathogenic alphaherpesvirus associated with domestic horses and wild equids. EHV-1 and recombinants of EHV-1 and EHV-9 are able to cause infections in non-equid animal species, particularly in captive settings. Many of the captive non-equid mammals are not naturally s...
Cymerys J, Słońska A, Tucholska A, Golke A, Chmielewska A, Bańbura MW.Equine herpesvirus 1 (EHV-1), like other members of the Alphaherpesvirinae subfamily, is a neurotropic virus causing latent infections in the nervous system of the natural host. In the present study, we have investigated EHV-1 replication (wild-type Jan-E strain and Rac-H laboratory strain) during long-term infection and during the passages of the virus in cultured neurons. The studies were performed on primary murine neurons, which are an excellent in vitro model for studying neurotropism and neurovirulence of EHV-1. Using real-time cell growth analysis, we have demonstrated for the first tim...
Maxwell LK.Since vaccination may not prevent disease, antiherpetic drugs have been investigated for the therapy of several equine herpesviruses. Drug efficacy has been assessed in horses with disease, but most evidence is in vitro, in other species, or empirical. Oral valacyclovir is most often administered in the therapy of equine herpesvirus type-1 (EHV-1) to protect adult horses from equine herpesvirus myeloencephalopathy, while oral acyclovir is frequently administered for EHV-5 infection in the therapy of equine multinodular pulmonary fibrosis. Other antiherpetic drugs are promising but require furt...
Mekuria ZH, El-Hage C, Ficorilli NP, Washington EA, Gilkerson JR, Hartley CA.Equine herpesvirus 5 (EHV5) is a commonly detected gammaherpesvirus, which, along with the closely related EHV2, constitute the only two known percaviruses that infect horses. Apart from detection in horse populations worldwide and the recent publication of the whole genome, there is little known about the biology and pathogenesis of this virus, with many assumptions made by parallels with EHV2. The long-term survival of gammaherpesviruses within infected hosts involves the establishment and maintenance of latency in selected cell and tissues types, particularly lymphocytes. A latent gammaherp...
Mesquita LP, Arévalo AF, Zanatto DA, Miyashiro SI, Cunha EMS, de Souza MDCC, Villalobos EMC, Mori CMC, Maiorka PC, Mori E.The equine herpesvirus type 1 (EHV-1) is an important cause of myeloencephalopathy and respiratory disease in horses. Animal models for EHV-1 infection have been specially developed using mice and Syrian hamsters (Mesocricetus auratus). However, few studies have attempted to evaluate the pathogenesis of EHV-1 infection in the central nervous system (CNS) and respiratory system of hamsters. Therefore, the aim of this study was to evaluate the pathogenesis of four Brazilian EHV-1 strains within the CNS and lungs of Syrian hamsters. Hamsters intranasally infected with A4/72, A9/92, A3/97, and Iso...
Zhao J, Poelaert KCK, Van Cleemput J, Nauwynck HJ.Equine herpesvirus type 1 (EHV-1) causes respiratory disease, abortion and neurological disorders in horses. Besides epithelial cells, CD172a monocytic cells become infected with EHV-1 in the respiratory mucosa and transport the virus from the apical side of the epithelium to the lamina propria en route to the lymph and blood circulation. Whether CD172a monocytic cells are specifically recruited to the infection sites in order to pick up virus is unknown. In our study, equine nasal mucosa explants were inoculated with EHV-1 neurological strains 03P37 and 95P105 or the non-neurological strains ...
Kirisawa R, Toishi Y, Akamatsu A, Soejima K, Miyashita T, Tsunoda N.In the spring of 2015, two stallions reared in Farms A and B in Hokkaido in Japan showed symptoms of equine coital exanthema. Equine herpesvirus 3 (EHV-3) was isolated from penis swab samples of both stallions, and the isolates from each stallion in Farms A and B were designated as SS-1 and YS-1 strains, respectively. BamHI restriction profiles of SS-1 and Japanese reference strain Iwate-1 were indistinguishable, but the BamHI-A fragment of YS-1 was larger than those of SS-1 and Iwate-1 by 1.9 kbp because of the lack of two BamHI sites. Nucleotide sequence analyses of glycoprotein G (gG), gB, ...
Toishi Y, Tsunoda N, Kirisawa R.Equine coital exanthema (ECE) has been reported in many countries, but equine herpesvirus 3 (EHV-3) has been isolated only once in Japan. In 2015, symptoms of ECE were found, and EHV-3 was isolated in two stallions. Valacyclovir, an anti-herpesvirus agent, was administered orally. The stallions rested from mating for more than two weeks, causing enormous financial losses because of their high fees. This is the first study in which valacyclovir was administered for ECE. Though valacyclovir treatment did not shorten the duration of healing, the affected area did not expand after administration o...
Negussie H, Gizaw D, Tesfaw L, Li Y, Oguma K, Sentsui H, Tessema TS, Nauwynck HJ.Infections with equine herpesviruses (EHVs) are widespread in equine populations worldwide. Whereas both EHV-1 and EHV-4 produce well-documented respiratory syndromes in equids, the contribution of EHV-2 and EHV-5 to disease of the respiratory tract is still enigmatic. This study describes the detection and genetic characterization of EHVs from equids with and without clinical respiratory disease. Virus-specific PCRs were used to detect EHV-1, -2, -4 and -5. From the total of 160 equids with respiratory disease, EHV-5 was detected at the highest prevalence (23.1%), followed by EHV-2 (20.0%), E...
Cymerys J, Słońska A, Brzezicka J, Tucholska A, Chmielewska A, Rola J, Malik P, Bańbura MW.Equine herpesvirus type 1 (EHV-1) causes respiratory infections, abortion and neurological disorders in horses. Molecular epidemiology studies have demonstrated that a single-point mutation in DNA polymerase gene, resulting in an amino acid variation (N752/D752), is significantly associated with the neuropathogenic potential of EHV-1 strains. The aim of the study was to elucidate if there are any differences between neuropathogenic (EHV-1 26) and non-neuropathogenic (Jan-E and Rac-H) EHV-1 strains in their ability to infect neuronal cells. For the tested EHV-1 strains, cytopathic effect (CPE) ...
Goehring LS, Brandes K, Ashton LV, Wittenburg LA, Olea-Popelka FJ, Lunn DP, Soboll Hussey G.Equine herpesvirus-associated myeloencephalopathy is the result of endothelial cell infection of the spinal cord vasculature with equine herpesvirus-1 (EHV-1) during cell-associated viraemia. Endothelial cell infection requires contact between infected peripheral blood mononuclear and endothelial cells. Inflammation generated during viraemia likely upregulates adhesion molecule expression on both cell types increasing contact and facilitating endothelial cell infection. Objective: Evaluating the role of anti-inflammatory drugs in decreasing endothelial cell infection with EHV-1. Methods: In vi...
Lopez KM, Fleming GJ, Mylniczenko ND.Reports of equine herpesvirus (EHV) 1 and EHV-9 causing clinical disease in a wide range of species have been well documented in the literature. It is thought that zebras are the natural hosts of EHV-9 both in the wild and in captive collections. Concerns about potential interspecies transmission of EHV-1 and EHV-9 in a mixed species savannah exhibit prompted serologic and polymerase chain reaction surveys. Eighteen Burchell's zebras ( Equus quagga ), 11 Hartmann's mountain zebras ( Equus zebra hartmannae), and 14 Thomson's gazelles ( Eudorcas thomsonii ) cohabitating the same exhibit were exa...
Franz M, Goodman LB, Van de Walle GR, Osterrieder N, Greenwood AD.A point mutation in the DNA polymerase gene in equine herpesvirus type 1 (EHV-1) is one determinant for the development of neurological disease in horses. Three recently conducted infection experiments using domestic horses and ponies failed to detect statistically significant differences in viral shedding between the neuropathogenic and non-neuropathogenic variants. These results were interpreted as suggesting the absence of a consistent selective advantage of the neuropathogenic variant and therefore appeared to be inconsistent with a systematic increase in the prevalence of neuropathogenic ...
Wagner B, Perkins G, Babasyan S, Freer H, Keggan A, Goodman LB, Glaser A, Torsteinsdóttir S, Svansson V, Björnsdóttir S.Neonatal foals respond poorly to conventional vaccines. These vaccines typically target T-helper (Th) cell dependent B-cell activation. However, Th2-cell immunity is impaired in foals during the first three months of life. In contrast, neonatal basophils are potent interleukin-4 (IL-4) producers. The purpose of this study was to develop a novel vaccine triggering the natural capacity of neonatal basophils to secrete IL-4 and to evaluate if vaccination resulted in B-cell activation and antibody production against EHV-1 glycoprotein C (gC). Neonatal vaccination was performed by oral biotinylated...
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 ...
Hernandez D, Yeo WM, Brooks MB, Ness SL, Divers TJ, Stokol T.OBJECTIVE To evaluate the effects of treatment of horses with standard platelet inhibitors on ex vivo inhibition of platelet activation by equine herpesvirus type I (EHV-I). ANIMALS II healthy adult horses. PROCEDURES In a double-blinded, placebo-controlled crossover study, horses were treated orally for 5 days with theophylline (5 mg/kg, q 12 h), pentoxifylline (10 mg/kg, q 12 h), clopidogrel bisulfate (4 mg/kg, q 24 h), acetylsalicylic acid (20 mg/kg, q 24 h), or placebo. Horses received all treatments, each separated by a 3-week washout period. Platelet-rich plasma was prepared from citrate...
Doubli-Bounoua N, Richard EA, Léon A, Pitel PH, Pronost S, Fortier G.The potential involvement of viruses in inflammatory airway disease (IAD) was previously investigated through either serology or PCR from nasopharyngeal swabs (NS). The aims of this study were to determine the prevalence and incidence of viral genome detection by qPCR in the equine airways, and their association with respiratory clinical signs. Both NS and tracheal washes (TW) were collected monthly on 52 Standardbred racehorses at training, over 27 consecutive months (581 samples). Equid herpesviruses (EHV)-1, -4, -2 and -5, equine rhinitis virus-A and -B (ERBV), equine adenovirus-1 and -2, e...
Stokol T, Serpa PBS, Zahid MN, Brooks MB.Equid herpes virus type-1 (EHV-1) is a major pathogen of horses, causing abortion storms and outbreaks of herpes virus myeloencephalopathy. These clinical syndromes are partly attributed to ischemic injury from thrombosis in placental and spinal vessels. The mechanism of thrombosis in affected horses is unknown. We have previously shown that EHV-1 activates platelets through virus-associated tissue factor-initiated thrombin generation. Activated platelets participate in thrombus formation by providing a surface to localize coagulation factor complexes that amplify and propagate thrombin genera...
Laval K, Van Cleemput J, Poelaert KC, Brown IK, Nauwynck HJ.Equine herpesvirus type 1 (EHV-1) is responsible for respiratory disorders, abortion and myeloencephalopathy (EHM) in horses. Two pathotypes of EHV-1 strains are circulating in the field: neurovirulent (N) and non-neurovirulent (NN). For both strains, CD172a monocytic cells are one of the main carrier cells of EHV-1 during primary infection, allowing the virus to invade the horse's body. Recently, we showed that EHV-1 NN strains showed a restricted and delayed replication in CD172a cells. Here we characterize the in vitro replication kinetics of two EHV-1N strains in CD172a cells and investiga...
Izume S, Kirisawa R, Ohya K, Ohnuma A, Kimura T, Omatsu T, Katayama Y, Mizutani T, Fukushi H.Equine herpesvirus type 4 (EHV-4) is one of the most important pathogens in horses. To clarify the key genes of the EHV-4 genome that cause abortion in female horses, we determined the whole genome sequences of a laboratory strain and 7 Japanese EHV-4 isolates that were isolated from 2 aborted fetuses and nasal swabs of 5 horses with respiratory disease. The full genome sequences and predicted amino acid sequences of each gene of these isolates were compared with of the reference EHV-4 strain NS80567 and Australian isolates that were reported in 2015. The EHV-4 isolates clustered in 2 groups w...
of surveillance testing, April to June 2016Continuing reports of abortion due to equine herpesvirus type 1 infectionInternational disease occurrence in the second quarter of 2016These 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.
Kupke A, Wenisch S, Failing K, Herden C.The olfactory epithelium (OE) is the only body site where neurons contact directly the environment and are therefore exposed to a broad variation of substances and insults. It can serve as portal of entry for neurotropic viruses which spread via the olfactory pathway to the central nervous system. For horses, it has been proposed and concluded mainly from rodent studies that different viruses, e.g., Borna disease virus, equine herpesvirus 1 (EHV-1), hendra virus, influenza virus, rabies virus, vesicular stomatitis virus can use this route. However, little is yet known about cytoarchitecture, p...
Proft A, Spiesschaert B, Izume S, Taferner S, Lehmann MJ, Azab W.The serine-threonine protein kinase encoded by gene (pUS3) of alphaherpesviruses was shown to modulate actin reorganization, cell-to-cell spread, and virus egress in a number of virus species. However, the role of the US3 orthologues of equine herpesvirus type 1 and 4 (EHV-1 and EHV-4) has not yet been studied. Here, we show that is not essential for virus replication in vitro. However, growth rates and plaque diameters of a -deleted EHV-1 and a mutant in which the catalytic active site was destroyed were significantly reduced when compared with parental and revertant viruses or a virus in w...
Anagha G, Gulati BR, Riyesh T, Virmani N.Equine herpesvirus 1 (EHV1) is a common pathogen of horses that causes upper respiratory tract disease, abortion, neonatal death and neurological disease. The neurological form of disease is called equine herpesvirus myeloencephalopathy (EHM). During the past decade, the incidence of EHM has been on the rise in Europe, North America, Australia and Asia. Some EHV1 isolates causing EHM exhibit a single-nucleotide polymorphism (SNP) in the DNA polymerase gene (ORF30) at position 2254 (A to G). Further, based on polymorphism in the ORF68, EHV1 isolates have been classified into different groups. T...
Walter J, Seeh C, Fey K, Bleul U, Osterrieder N.Equine herpesvirus myeloencephalopathy (EHM) is a severe manifestation of equine herpesvirus 1 (EHV-1) infection. Prevention and treatment of EHM during EHV-1 outbreaks is critical, but no reliable and tested specific medication is available. Due to the thromboischemic nature of EHM and due to the fact that EHV-1 entry in cells is blocked by heparin, it was hypothesized that this compound may be useful in reduction of EHM incidence and severity. Therefore, during an acute EHV-1 outbreak with the neuropathogenic G/D Pol variant, metaphylactic treatment with heparin to prevent EHM was initiated....
Charlton KM, Mitchell D, Girard A, Corner AH.During an outbreak of abortion caused by equine herpesvirus 1, a neurologic disease characterized clinically by dullness and ataxia occurred in several mares. Equine herpesvirus 1 was isolated from brain and lung of two severely affected mares. Histologically, both mares had disseminated meningoencephalomyelitis characterized by necrotizing arteritis, focal malacia in grey and white matter of brain and spinal cord, and accumulation of lymphocytes and neutrophils in paravertebral ganglia. Eosinophilic intranuclear inclusion bodies occurred in foci of necrosis in thyroid adenomas of both mares.
Taniguchi A, Fukushi H, Matsumura T, Yanai T, Masegi T, Hirai K.Pathogenicity of equine herpesvirus 9 (EHV-9), a new type of equine herpesvirus isolated from Gazella thomsoni, in horses was investigated by intranasal inoculation of EHV-9 (10(7) pfu) to two conventionally reared 8-months old half-bred weanling horses. Fever higher than 39 degrees C was recorded. Virus was recovered from nasal swabs and peripheral blood mononuclear cells. Both horses developed neutralizing antibody to EHV-9. Perivascular infiltration of mononuclear cells and glial reaction were found in the olfactory and limbic systems. The results suggested that EHV-9 has a pathogenicity in...
Peterson RB, Goyal SM.A comparative study was carried out to determine the relative sensitivities of eight different cell culture systems to six different herpesviruses of animals. The cells used were: OFL (ovine fetal lung), ML (mink lung), FK (ferret kidney), PTK-2 (potoroo kidney), TEK (turkey embryo kidney), ED (equine dermal), BT (bovine turbinate), and PK15 (porcine kidney). The viruses tested were: PRV (pseudorabies) of swine, CPHV (caprine herpesvirus), IBRV (infectious bovine rhinotracheitis virus), DN-599 strain of bovine herpesvirus type 4, EHV-1 (equine herpesvirus), and CHV (canine herpesvirus). On the...
Willoughby R, Ecker G, McKee S, Riddolls L, Vernaillen C, Dubovi E, Lein D, Mahony JB, Chernesky M, Nagy E.The response of horses exposed to three common respiratory viruses was studied by measuring tracheal mucociliary clearance rates in the trachea. Tracheal clearance rates (TCR) were determined before, during illness and following recovery in horses exposed to equine rhinovirus (ERhV-2), equine influenza virus (EIV) and equine herpesvirus (EHV-4) by means of lateral scintigraphs made following an injection of technetium-99m sulphide colloid into the tracheal lumen. In six horses exposed to ERhV-2, TCR remained within normal limits. Exposure to EIV resulted in reduced TCR in six of seven horses, ...
Wilsterman S, Soboll-Hussey G, Lunn DP, Ashton LV, Callan RJ, Hussey SB, Rao S, Goehring LS.Infection with equine herpesvirus-1 (EHV-1) causes respiratory disease, late term abortions and equine herpesvirus myeloencephalitis (EHM) and remains an important problem in horses worldwide. Despite increasing outbreaks of EHM in recent years, our understanding of EHM pathogenesis is still limited except for the knowledge that a cell-associated viremia in peripheral blood mononuclear cells (PBMCs) is a critical link between primary respiratory EHV-1 infection and secondary complications such as late-term abortion or EHM. To address this question our objective was to identify which PBMC subpo...
Pusterla N, Mapes S, David Wilson W.The objective of this study was to detect and characterize latent equine herpes virus (EHV)-1 and -4 from the submandibular (SMLN) and bronchial lymph (BLN) nodes, as well as from the trigeminal ganglia (TG) of 70 racing Thoroughbred horses submitted for necropsy following sustaining serious musculoskeletal injuries while racing. A combination of nucleic acid precipitation and pre-amplification steps was used to increase analytical sensitivity. Tissues were deemed positive for latent EHV-1 and/or -4 infection when found PCR positive for the corresponding glycoprotein B (gB) gene in the absence...
Studdert MJ.DNA was prepared from 43 equine herpesvirus type 1 (EHV 1) isolates, 11 of which were from horses with respiratory disease, 22 from aborted equine foetuses, and 10 from foals that died perinatally. The restriction endonuclease DNA fingerprints of 10 of the 11 respiratory isolates, known with certainty to have been recovered from horses with respiratory disease, were entirely different from all but 3 of the 32 foetal or perinatal foal isolates. The exceptional respiratory isolate, EHV 1 Army 183, had a foetal (F) strain fingerprint but this virus cannot be said with certainty to have been isola...
Slater JD, Gibson JS, Field HJ.Both intranasal (i.n.) and intracerebral (i.c.) inoculation of mice with wild-type equine herpesvirus type 1 (wt EHV-1) caused clinical signs and mortality. Virus could be recovered from target organs (turbinates, lungs and blood) for several days. By contrast, the thymidine kinase (TK)-deficient deletion mutant PR1 produced markedly less clinical disease following both i.n. and i.c. inoculation, and, in particular, no mortality occurred. PR1 did, however, establish productive infections following either route of inoculation. High titres of virus were recovered from target organs although viru...
Dunowska M, Wilks CR, Studdert MJ, Meers J.To identify viruses associated with respiratory disease in young horses in New Zealand. Methods: Nasal swabs and blood samples were collected from 45 foals or horses from five separate outbreaks of respiratory disease that occurred in New Zealand in 1996, and from 37 yearlings at the time of the annual yearling sales in January that same year. Virus isolation from nasal swabs and peripheral blood leukocytes (PBL) was undertaken and serum samples were tested for antibodies against equine herpesviruses (EHV-1, EHV-2, EHV-4 and EHV-5), equine rhinitis-A virus (ERAV), equine rhinitis-B virus (ERBV...
Smith DJ, Hamblin AS, Edington N.Evidence is presented to show that activation of endothelial and leucoyte adhesion molecules is a key step in transferring virus from infected leucocytes; and determines the restricted tissue tropism. A range of tissues from 2 experimentally infected mares in late pregnancy at 4 and 8 days after infection with EHV-1 were compared with those from normal pregnant and nonpregnant mares. Rabbit antisera to equine activated endothelial cell molecules were used to identify which tissues expressed these molecules in normal nongravid and gravid mares, and to investigate whether the range of tissues wa...
Smith KC, Whitwell KE, Mumford JA, Gower SM, Hannant D, Tearle JP.Twelve Welsh Mountain pony mares in late gestation were infected intranasally with EHV-1 (AB4 isolate) at dose rates from 10(3) to 10(7.3) TCID50. This resulted in 3 cases of paresis, at Days 9, 10 and 12 after inoculation, and 5 abortions, at Days 6, 9, 18, 19 and 20. Euthanasia was performed between Days 6 and 21, with collection of uterine specimens for histopathology, virus isolation and immunoperoxidase staining from the pregnant horn, non-pregnant horn and body. EHV-1 replication in endometrial vessels was detected as early as Day 6 and was maximal at Days 9-11, when widespread thrombois...
Baumann RP, Staczek J, O'Callaghan DJ.Equine herpesvirus type one (EHV-1) defective interfering (DI) particle DNA fragments were inserted into the XbaI site of the plasmid vector pACYC184. Five DI XbaI fragments, which ranged in molecular weight from 4.5 to 6.7 MDa, were selected for detailed analysis. Each DI DNA clone was labeled with 32P-deoxynucleotides by nick translation and hybridized to genomic digests of EHV-1 standard (STD) DNA bound to nitrocellulose. All five clones were shown to hybridize to DNA sequences derived from the left terminus (0.0-0.04 map units) of the long (L) region and from the short (S) region inverted ...
Jackson TA, Osburn BI, Cordy DR, Kendrick JW.Experimental infection with equine herpesvirus 1 (rhinopneumonitis) resulted in neurologic disease in 8 of 15 inoculated horses. Nonpregnant animals did not develop clinical disease, and microscopic examination of tissues revealed no changes. In all mares between 3 and 9 months of gestation, a neurologic syndrome appeared 6 to 8 days after inoculation. Mares inoculated when 10 months pregnant did not develop neurologic disorders, but several aborted. The histopathologic change common to both sequelae was vasculitis, involving smaller arteries and veins. Although blood vessel changes were detec...
Craig MI, Barrandeguy ME, Fernández FM.Equine herpesvirus 2 is a gamma-herpesvirus that infects horses worldwide. Although EHV-2 has been implicated in immunosuppression in foals, upper respiratory tract disease, conjunctivitis, general malaise and poor performance, its precise role as a pathogen remains uncertain. The purpose of the present study was to analyse the incidence of EHV-2 in an Argentinean horse population and correlate it with age and clinical status of the animals. Results: A serological study on 153 thoroughbred racing horses confirmed the presence of EHV-2 in the Argentinean equine population. A virus neutralizatio...
Bell SA, Pusterla N, Balasuriya UB, Mapes SM, Nyberg NL, MacLachlan NJ.Equids are commonly infected by herpesviruses, but isolation of herpesviruses from mules has apparently not been previously reported. Furthermore, the genomic relationships among the various equid herpesviruses are poorly characterized. We describe the isolation and preliminary characterization of a mule gammaherpesvirus tentatively identified as asinine herpesvirus-2 (AHV-2; also designated equid herpesvirus-7 (EHV-7)) from the nasal secretions (NS) of a healthy mule in northern California. The virus was initially identified by transmission electron microscopic examination of lysates of cell ...
Muscat KE, Padalino B, Hartley CA, Ficorilli N, Celi P, Knight P, Raidal S, Gilkerson JR, Muscatello G.The risk of respiratory disease in the transported horse can increase as a consequence of immunosuppression and stress associated primarily with opportunistic bacterial proliferation and viral reactivation. This study examines the ecology of equid herpesviruses (EHV) in these horses, exploring reactivation and changes in infection and shedding associated with transport, and any potential contributions to transport-related respiratory disease. Twelve horses were subjected to an 8-h road-transport event. Antibodies to EHV-1 and EHV-4 were detected by ELISA in serum collected prior to, immediatel...
Hussey GS, Goehring LS, Lunn DP, Hussey SB, Huang T, Osterrieder N, Powell C, Hand J, Holz C, Slater J.Equine herpesvirus myeloencephalitis (EHM) remains one of the most devastating manifestations of equine herpesvirus type 1 (EHV-1) infection but our understanding of its pathogenesis remains rudimentary, partly because of a lack of adequate experimental models. EHV-1 infection of the ocular vasculature may offer an alternative model as EHV-1-induced chorioretinopathy appears to occur in a significant number of horses, and the pathogenesis of EHM and ocular EHV-1 may be similar. To investigate the potential of ocular EHV-1 as a model for EHM, and to determine the frequency of ocular EHV-1, our ...
Diallo IS, Hewitson GR, de Jong A, Kelly MA, Wright DJ, Corney BG, Rodwell BJ.Twelve nasal swabs were collected from yearling horses with respiratory distress and tested for equid herpesvirus 1 (EHV-1) and equid herpesvirus 4 (EHV-4) by real-time PCR targeting the glycoprotein B gene. All samples were negative for EHV-1; however, 3 were positive for EHV-4. When these samples were tested for EHV-2 and EHV-5 by PCR, all samples were negative for EHV-2 and 11 were positive for EHV-5. All three samples that were positive for EHV-4 were also positive for EHV-5. These three samples gave a limited CPE in ED cells reminiscent of EHV-4 CPE. EHV-4 CPE was obvious after 3 days and...
Ostlund EN.Two viruses, EHV-1 and EHV-4, are now known to be responsible for disease conditions formerly considered caused by "equine rhinopneumonitis virus." Although these viruses share several laboratory and clinical features, they differ in epidemiology and pathogenic potential. EHV-4 is primarily associated with clinical respiratory disease, whereas EHV-1 is more frequently isolated from aborted fetuses, sickly foals, and neurologic cases. Both viruses frequently establish latent infections, but the relevance of latency to clinical disease is unclear. Diagnosis based on identification of the pathoge...
Goehring LS, van Maanen C, Berendsen M, Cullinane A, de Groot RJ, Rottier PJ, Wesselingh JJ, Sloet van Oldruitenborgh-Oosterbaan MM.Equid herpesvirus type 1 (EHV-1)-associated myeloencephalopathy (EHM) may follow an infection with the virus in horses. This study tested three hypotheses: (1) a large inhaled dose of a neuropathogenic EHV-1 strain would induce a cell-associated viraemia in all infected horses; (2) neurological disease will only occur in viraemic horses, and (3) the cerebrospinal fluid (CSF) composition following EHV-1 viraemia will be an indicator for EHM. Four EHV-1 seronegative horses were inoculated with EHV-1 by inhalation. Three developed clinical signs of neurological disease, which were mild in two hor...
Robinson RA, Tucker PW, Dauenhauer SA, O'Callaghan DJ.Genomic DNA sequences of equine herpesvirus type 1 (EHV-1) have been cloned as BamHI and EcoRI restriction fragments into the plasmid pBR322 and propagated in Escherichia coli. With the exception of two EcoRI restriction fragments that reside in the S region of the viral genome, all of the cloned fragments demonstrated the same electrophoretic mobilities, restriction cleavage sites, and blot-hybridization patterns as did the parent fragments produced by BamHI or EcoRI digestion of virion DNA. The EcoRI J fragment and the BamHI E fragment of the L-region terminus were cloned after the addition ...
Garré B, Shebany K, Gryspeerdt A, Baert K, van der Meulen K, Nauwynck H, Deprez P, De Backer P, Croubels S.The purpose of this study was twofold. The first aim was to evaluate the oral bioavailability and pharmacokinetics (PKs) of acyclovir in horses after intravenous (i.v.) administration and after oral administration of acyclovir and its prodrug, valacyclovir. Second, we aimed to combine these PK data with pharmacodynamic (PD) information, i.e., 50% effective concentrations (EC(50) values) from in vitro studies, to design an optimal dosage schedule. Three treatments were administered to healthy adult horses: 10 mg of acyclovir/kg of body weight delivered as an i.v. infusion over 1 h, 20 mg of acy...
Van Cleemput J, Poelaert KCK, Laval K, Impens F, Van den Broeck W, Gevaert K, Nauwynck HJ.Pollens are well-known triggers of respiratory allergies and asthma. The pollen burden in today's ambient air is constantly increasing due to rising climate change and air pollution. How pollens interact with the respiratory mucosa remains largely unknown due to a lack of representative model systems. We here demonstrate how pollen proteases of Kentucky bluegrass, white birch and hazel selectively destroy integrity and anchorage of columnar respiratory epithelial cells, but not of basal cells, in both ex vivo respiratory mucosal explants and in vitro primary equine respiratory epithelial cells...
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...
Lang A, de Vries M, Feineis S, Müller E, Osterrieder N, Damiani AM.A peptide-based enzyme-linked immunosorbent assay (ELISA) for discrimination between serological responses to equine herpesvirus type 1 (EHV-1) and 4 (EHV-4) was developed. Three and four peptides for EHV-1 and EHV-4, respectively, were designed and studied initially in the ELISA using sera from foals infected experimentally. The most promising peptide pair, derived from EHV-1 glycoprotein E and EHV-4 glycoprotein G, was evaluated further using acute and convalescent sera from horses infected experimentally and naturally as well as a panel of horse field sera. Ten pre- and post-vaccination ser...
Allen GP.To evaluate a technique for identifying horses latently infected with neuropathogenic strains of equine herpesvirus-1 (EHV-1). Methods: 36 adult mares, 24 of which were experimentally infected as weanlings with neuropathogenic or nonneuropathogenic EHV-1. Methods: Mandibular lymph node (MLN) tissue was obtained from each horse via biopsy during general anesthesia. Purified DNA from MLNs was tested for EHV-1 DNA by use of a magnetic bead, sequencecapture, nested PCR assay. For MLNs that contained EHV-1 DNA, the 256-bp DNA fragments amplified via sequence-capture nested PCR were sequenced to det...
Gershwin LJ, Netherwood KA, Norris MS, Behrens NE, Shao MX.Vaccination of horses is performed annually or semi-annually with multiple viral antigens, either in a combination vaccine or as separate injections. While this practice undoubtedly prevents infection from such diseases as rabies, equine influenza, West Nile virus, and equine herpes virus, the procedure is not without repercussions. Hypersensitivity reactions, including fatal anaphylactic shock, after vaccination, although uncommon, have increased in incidence in recent years. Studies reported herein document the development of IgE antibodies against non-target antigen components of equine vir...
