Topic:Equine Herpesvirus
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.
Antibodies against equine herpesvirus 1 in the cerebrospinal fluid in the horse. Neutralizing antibodies against equine herpesvirus 1 were measured in serum and cerebrospinal fluid of 16 horses and ponies from a closed herd both before and after vaccination with modified live equine herpesvirus 1. These titers were also measured in 22 neurologically normal and 15 neurologically abnormal horses at a teaching hospital. Animals from the closed herd had prevaccination serum titers up to 1:8 and postvaccination serum titers up to 1:128. Horses from the teaching hospital had serum titers up to 1:64. Cerebrospinal fluid titers were not detected in the vaccinated horses or the neu...
Endoscopic and virological observations on respiratory disease in a group of young Thoroughbred horses in training. A group of racehorses in training was examined on several occasions with a fibreoptic endoscope and monitored for viral infection. Only equine herpes virus-2 (EHV-2) infection was detected. Pharyngeal lymphoid hyperplasia (PLH) was present in all horses and decreased in severity with age. There was no association between PLH severity and antibody titres to EHV-1, or with the isolation of EHV-2. Finishing position in races was not affected by PLH severity. Exercise induced pulmonary haemorrhage (EIPH) was evident on 23 out of 49 (47 per cent) examinations after maximal speed training exercise. ...
Inclusions in equine cytologic specimens. Inclusions and cellular changes were seen in cytologic specimens from 1 healthy horse, 6 horses hospitalized because of respiratory problems, and 1 horse hospitalized because of colic and hepatitis. Two bronchial aspirates contained detached ciliated cytoplasmic tufts and cytoplasmic inclusions characteristic of the specific degenerative process called ciliocytophthoria. These changes and inclusions resembled those seen in bronchial aspirates from human beings with parainfluenza virus infection. Four bronchial aspirates and 2 serous fluid specimens had nuclear inclusions resembling those seen ...
A new field strain of equine abortion virus (equine herpesvirus-1) among Kentucky horses. From restriction endonuclease characterization of the DNA of 317 isolates of equine abortion virus (equine herpesvirus-1; EHV-1) from 176 epizootically unrelated outbreaks of equine virus abortion occurring over 24 years in Kentucky, an epizootic pattern and variation of the virus have emerged. Two electropherotypes of EHV-1 (1P and 1B) accounted for greater than 90% of the nonvaccine-related abortion isolates examined. From 1960 to 1981, EHV-1 1P was the predominant isolate circulating in the central Kentucky area and the cause of greater than 80% of EHV-1-related abortions. In 1981, the occu...
Molecular pathogenesis of equine coital exanthema: restriction endonuclease digestions of EHV-3 DNA and indications of a unique XbaI cleavage site. Equine herpesvirus type 3 (EHV-3) DNA, isolated from purified virions of the large-plaque strain, was digested with the restriction endonucleases XbaI, Bg/II, EcoRI, and HindIII. Several lines of evidence indicated that the DNA extracted from purified virions was composed of long (L) and short (S) components and was present as two isomeric forms, P and IS. The evidence included: (i) after electrophoresis on agarose gels, the summed molecular weights of the digestion products exceeded that expected from intact, unit size DNA; (ii) quantitative measurements of radioactivity (molar ratios) indica...
[Neurological disorders caused by equine herpesvirus type 1 and cauda equina neuritis in horses]. The differences in aetiology, symptomatology, pathomorphology, diagnosis and therapy between the nervous form (paralytic form) of Equine Herpes Virus, type 1, and Neuritis Caudae Equinae are reviewed. The conclusion is that in most cases it is possible to differentiate between these two clinical syndromes.
Molecular epidemiology and pathogenesis of some equine herpesvirus type 1 (equine abortion virus) and type 4 (equine rhinopneumonitis virus) isolates. Representative strains of EHV isolated from an aborted foetus and from a horse with rhinopneumonitis in New Zealand had restriction endonuclease DNA fingerprints typical of those usually associated with these syndromes elsewhere and now designated EHV1 and 4 respectively. EHV1 was isolated from the brain and spinal cord of a 4-year-old gelding that died of myeloencephalitis. A mare on the same farm, at about the same time as the gelding developed myeloencephalitis, aborted and EHV1 was isolated from the tissues of the aborted foetus. Restriction endonuclease DNA fingerprints of the viruses iso...
Pathogenicity of equine herpesvirus 1 subtype 2 for foals and adult pony mares. Three pony mares and 4 pony foals were inoculated with a subtype 2 strain of equine herpesvirus 1. Foals had periods of fever 12 h and 2.5 days after inoculation and leukopenia, involving both neutrophils and lymphocytes, followed by leukocytosis. Mares had transient fever and leukopenia 24 hours after inoculation that were less severe than in foals. An increase in circulating virus-neutralizing antibody was seen in 2 of 3 inoculated mares, but not in foals. Attempts to isolate virus from blood were unsuccessful. These studies show that equine herpesvirus 1 subtype 2 is a mild pathogen for pon...
Electron microscopy of equine respiratory viruses in organ cultures of equine fetal respiratory tract epithelium. Organ cultures of equine fetal tracheal and nasal turbinate epithelium were inoculated with equine influenza virus-A1 (EIV-A1), equine herpesvirus-1 (EHV-1), or equine rhinovirus-1 (ERV-1). Infected organ cultures were processed for scanning and transmission electron microscopy at various intervals and were compared with noninfected controls. Organ cultures inoculated with ERV-1 appeared normal with the exception of rare island-like lesions in infected nasal turbinate. Virus particles were not seen in thin sections of organ cultures infected with ERV-1. The EHV-1 caused extensive loss of the e...
Functional and ultrastructural changes in neutrophils from mares and foals experimentally inoculated with a respiratory tract strain of equine herpesvirus-1. Neutrophils isolated from venous blood of adult and foal ponies inoculated with equine herpesvirus-1 were evaluated by in vitro function tests and by electron microscopy. Foals had fever and severe neutropenia 24 hours after inoculation; increased neutrophil random migration under agarose and decreased antibody-dependent cell-mediated cytotoxicity were significant at 24 hours, but values had returned to preinoculation levels by 72 hours. Mares had fever and leukopenia of less severity, increases in neutrophil migration, and longer persistence of primary granule release than were seen in foals....
Growth kinetics of equine respiratory tract viruses in cell and organ cultures. Growth kinetics of equine influenza virus-A1, equine herpesvirus-1, and equine rhinovirus-1 were determined in susceptible cell monolayers and in organ cultures of equine fetal tracheal and nasal turbinate epithelium. Equine influenza virus-A1 was replicated in cell and organ cultures and was released more readily and for longer periods from nasal turbinate epithelium than from tracheal epithelium. Equine herpesvirus-1 was also replicated in cell and organ cultures. During the first 24 hours after inoculation, equine herpesvirus-1 was released more readily from tracheal epithelium than from na...
Immunologic relationships between equine herpesvirus type 1 (equine abortion virus) and type 4 (equine rhinopneumonitis virus). The specificity of selected immune responses to equine herpesvirus type 1 (EHV-1) and type 4 (EHV-4) was examined in 3 colostrum-deprived specific-pathogen-free foals. Single foals were vaccinated with inactivated EHV-1, inactivated EHV-4, or control cell lysate plus adjuvant followed by successive intranasal challenge exposures with EHV-1 and EHV-4 or with EHV-4 and EHV-1. Vaccination with inactivated virus preparations elicited cellular immune responses and antibody which were augmented by subsequent challenge exposures. Cellular immune responses, as measured by in vitro lymphocyte blastogen...
Equine cytomegalovirus: structural proteins of virions and nucleocapsids. Enveloped virions and nucleocapsids of equine cytomegalovirus (ECMV; equine herpesvirus type 2) have been purified from the supernatants and the nuclear extracts of infected rabbit kidney (RK) cells, respectively, and their structural protein compositions have been analyzed. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that ECMV nucleocapsids were composed of nine proteins (average molecular weights = 148K, 52K, 49.5K, 46K, 43.5K, 38.5K, 27K, 20K, and 18K), which together constituted 89% of the total nucleocapsid protein on the basis of incorporated 3H-labeled am...
Trials of an inactivated equid herpesvirus 1 vaccine: challenge with a subtype 1 virus. Vaccinated yearlings , two-year-old and in-foal pony mares with appropriate controls were exposed to aerosols of a subtype 1 virus one to two months after two or three vaccinations; all became infected. No obvious differences in the febrile responses, clinical signs and subsequent abortions were found between vaccinated and control mares. All vaccinated yearlings and two-year-old ponies developed a febrile respiratory disease but this was less severe than that suffered by the controls and the amounts and duration of virus shedding were reduced.
Trials of an inactivated equid herpesvirus 1 vaccine: challenge with a subtype 2 virus. Serological responses following two and three doses of an inactivated equid herpesvirus 1 ( EHV -1) vaccine containing a subtype 1 strain were examined in yearling ponies. Complement fixing antibody responses were significantly higher against the subtype 1 vaccine strain than against a subtype 2 virus. Complement fixing antibody responses declined rapidly after the second dose of vaccine and had returned to almost pre-vaccination levels eight weeks after the second dose of vaccine. Complement fixing antibody titres to the heterologous subtype 2 strain increased after each successive dose of va...
Coestablishment of persistent infection and oncogenic transformation of hamster embryo cells by equine cytomegalovirus. Semipermissive, primary hamster embryo (HE) cells were morphologically transformed in vitro by infection with UV-irradiated equine cytomegalovirus (equine herpesvirus type 2; ECMV). Cell lines (designated EC-1-3) were established independently from foci and were shown to exhibit growth and biological properties typically associated with transformed cells: altered morphology, loss of contact inhibition, increased saturation density, decreased generation time, immortality in culture, normal growth in low concentrations of serum, colony formation in soft agar, and resistance to ECMV superinfectio...
[Current virus diseases in horses. Diseases in foals and respiratory tract infections]. At the moment, horse praxis is confronted by two disease complexes which are difficult to fight against as well in prophylaxis as in therapy, but which get an increasing importance. First they concern virus infections of the foals and second primary virus-caused respiratory diseases. Foals get infected during the embryonal/fetal development, in the perinatal or postnatal period. Normally the infection is caused by latent infected, clinical healthy mares, or in the postnatal period by ubiquitous, normally opportunistic socalled problem-viruses, i.e. equine herpes-viruses 1 and 2, rota-, corona-...
Comparative diagnostic value of the gel diffusion test and virus isolation in cell culture for detecting equine herpesvirus type 1 (EHV-1). The gel diffusion test was applied direct to field samples from cases of equine abortion, foal mortality and equine paralysis due to equine herpesvirus type 1 (EHV-1). Following polyethylene glycol concentra tion of viral antigen, one line was formed against EHV-1 antiserum after 24 hours incubation at 25°C. Tests carried out simultaneously on 41 field samples showed a high correlation between diagnosis based on this test and virus isolation in primary lamb kidney cell culture. Advantages of gel diffusion over isolation of virus in cell culture were its rapidity and simplicity. The precipit...
Ulcerative duodenitis in foals. Seven foals aged 18 days to 3 1/2 months had either single or multiple full-circumference segments or long antimesenteric bands of necrotizing duodenitis, sharply delineated from adjacent viable duodenum. Perforation of the necrotic wall had occurred in all foals, leading to acute fibrinous peritonitis. On the mucosal surface severe diffuse, acute inflammation and ulceration involved the anterior half of the duodenum. Two further foals, aged 28 and 30 days, had lesions that are believed to be a chronic form of this disease. Both foals had a thickened duodenal wall, with large areas of mucosa r...
Equine herpesvirus abortion in Australia 1977 to 1982. Until 1977 no case of abortion caused by equine herpesvirus 1 (EHV1) had been recorded in Australia although the virus, called equine rhinopneumonitis virus, had been known to have been present at least since 1962. Outbreaks of EHV1 abortion occurred in New South Wales in 1977 and in 1981. Sporadic cases of EHV1 abortion had been confirmed in some parts of Australia each year since 1975. It was concluded that an abortigenic subtype of EHV1 had been introduced to Australia in 1977 and that the previously endemic respiratory subtype occasionally caused abortion. Virus isolation in a variety of c...
The spectrum of antiviral activities of acyclovir in vitro and in vivo. In vitro sensitivity data suggest that acyclovir should be effective against clinical manifestations of herpes simplex virus types 1 and 2, varicella-zoster virus and possibly Epstein-Barr virus. The clinical potential against herpes simplex virus types 1 and 2 is further supported by results in animal models. Human cytomegalovirus and the veterinary herpes viruses, with the possible exception of equine herpes virus type 1, may be insufficiently sensitive to be amenable to treatment.
Relative activities of acyclovir and BW759 against Aujeszky’s disease and equine rhinopneumonitis viruses. Compound BW759 (9-[2-hydroxy-1-(hydroxymethyl)ethoxymethyl]guanine) was shown to be about 230 times more active than acyclovir (9-[2-hydroxyethoxymethyl]guanine) (ACV) against Equid herpesvirus type 1 infection in Syrian hamsters and was more effective against Aujeszky's disease in mice. The therapeutic superiority of BW759 over ACV was greater than expected from quantitative inhibitory results in tissue culture with these viruses. When administered to hamsters at dose rates sufficient to prevent any Equid herpesvirus type 1-induced mortality (100 mg of ACV per kg per day; 3 mg of BW759 per kg...
The pathogenicity in mice of respiratory, abortion and paresis isolates of equine herpesvirus-1. Eleven isolates of equine herpesvirus-1 (subtype 1) all infected the brain following intracerebral inoculation of 2 d.o. mice. Most isolates were from cases of paresis, abortion or respiratory disease in the U.K., but established strains were also included. They divided into two subgroups. The 5 less pathogenic isolates were characterized by being restricted predominantly to the olfactory lobes. The 6 pathogenic isolates included the three known to cause equine paresis and were detected in neurones throughout the brain as well as giving rise to viraemia and infecting bronchial and renal epithe...