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1.
A single nucleotide polymorphism in the equine herpesvirus 1 (EHV-1) DNA polymerase gene (ORF30 A2254 to G) has been associated with clinical signs of equine herpes myeloencephalopathy (EHM). The purpose of our study was to determine the odds ratio for this genetic marker and EHM using a panel of field isolates from North America collected over the past twenty-three years. EHV-1 isolates cultured at the Cornell University Animal Health Diagnostic Laboratory from 1984 to 2007 were retrieved along with their clinical histories. DNA was extracted from these EHV-1 cultures and allelic discrimination was performed using real-time PCR. The results were confirmed by sequencing of the target region in ORF30. PCR and sequencing were in 100% agreement and showed that 19 out of the 176 isolates had the ORF30 G2254 allele (11%), of which16 were EHM cases and 3 respiratory or abortion cases. The odds of having neurologic disease with the ORF30 G2254 genotype were computed as 162 times greater than those with the opposite allele ORF30 A2254 (95% confidence interval: 35–742). Despite this strong statistical significance, 24% (5/21) of horses with neurologic disease in our study population harbored the “non-neurologic” form of the allele (ORF30 A2254), suggesting that other factors may also contribute to the onset of EHM.  相似文献   

2.
Latent equine herpesvirus type 1 (EHV-1) infection is common in horse populations worldwide and estimated to reach a prevalence nearing 90% in some areas. The virus causes acute outbreaks of disease that are characterized by abortion and sporadic cases of myeloencephalopathy (EHM), both severe threats to equine facilities. Different strains vary in their abortigenic and neuropathogenic potential and the simultaneous occurrence of EHM and abortion is rare. In this report, we present clinical observations collected during an EHV-1 outbreak caused by a so-called “neuropathogenic” EHV-1 G2254/D752 polymerase (Pol) variant, which has become more prevalent in recent years and is less frequently associated with abortions. In this outbreak with 61 clinically affected horses, 6/7 pregnant mares aborted and 8 horses developed EHM. Three abortions occurred after development of EHM symptoms. Virus detection was performed by nested PCR targeting gB from nasal swabs (11 positive), blood serum (6 positive) and peripheral blood mononuclear cells (9 positive) of a total of 42 horses sampled. All 6 fetuses tested positive for EHV-1 by PCR and 4 by virus isolation. Paired serum neutralization test (SNT) on day 12 and 28 after the index case showed a significant (≥ 4-fold) increase in twelve horses (n = 42; 28.6%). This outbreak with abortions and EHM cases on a single equine facility provided a unique opportunity for the documentation of clinical disease progression as well as diagnostic procedures.  相似文献   

3.
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4.
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 subpopulation(s) are infected during viremia and may therefore play a role in transmitting the virus to the vascular endothelium of the spinal cord or pregnant uterus. PBMCs from 3 groups of animals were collected between days 4 and 9 following experimental infection with EHV-1 strain Findlay/OH03 or strain Ab4. PBMCs were labeled with primary antibodies selective for CD4+ or CD8+ T lymphocytes, B-lymphocytes, or monocytes and positively selected using magnetic bead separation. Cell numbers and EHV-1 genome numbers in each subpopulation were then determined using quantitative PCR for β-actin and the EHV-1 glycoprotein B, respectively. Viral genomic DNA was found in all PBMC subpopulations; the CD8+ lymphocytes were most frequently positive for viral DNA, followed by B-lymphocytes. These differences were statistically significant in horses infected with the EHV-1 strain Findlay/OH03, and ponies with Ab4. These results differ from what has been reported in in vitro studies, and indicate that different PBMC subpopulations may play different roles in EHV-1 viremia.  相似文献   

5.
Infection with equine herpesvirus-1 (EHV-1) causes respiratory disease, late-term abortions and equine herpesvirus myeloencephalitis (EHM). Our understanding of EHM pathogenesis is limited except for the knowledge that EHV-1 infected, circulating peripheral blood mononuclear cells (PBMC) transport virus to the central nervous system vasculature causing endothelial cell infection leading to development of EHM. Our objective was to develop a model of CNS endothelial cell infection using EHV-1 infected, autologous PBMC. PBMCs, carotid artery and brain endothelial cells (EC) from 14 horses were harvested and grown to confluency. PBMC or ConA-stimulated PBMCs (ConA-PBMCs) were infected with EHV-1, and sedimented directly onto EC monolayers ('contact'), or placed in inserts on a porous membrane above the EC monolayer ('no contact'). Cells were cultured in medium with or without EHV-1 virus neutralizing antibody. Viral infection of ECs was detected by cytopathic effect. Both brain and carotid artery ECs became infected when cultured with EHV-1 infected PBMCs or ConA-PBMCs, either in direct contact or no contact: infection was higher in carotid artery than in brain ECs, and when using ConA-PBMCs compared to PBMCs. Virus neutralizing antibody eliminated infection of ECs in the no contact model only. This was consistent with cell-to-cell spread of EHV-1 infection from leucocytes to ECs, demonstrating the importance of this mode of infection in the presence of antibody, and the utility of this model for study of cellular interactions in EHV-1 infection of ECs.  相似文献   

6.
Equine respiratory viral infections cause significant worldwide disease and economic loss. Common causes include equine influenza virus (EIV) and equine herpesviruses-1 and -4 (EHV-1 and -4), and risk of exposure to these agents may be highest in young horses commingling at sales and competitive events. A surveillance study was conducted at two horse shows and two Thoroughbred sales to determine whether horses shed EHV-1, EHV-4, or EIV on arrival, or 2-4 days later, and whether shedding was associated with identifiable risk factors. Real-time polymerase chain reaction assays were used to detect EHV-1, EHV-4, and EIV nucleic acid in nasal swabs obtained from 369 horses at the four events. In response to evidence of clinical disease, 82 additional horses were sampled at two farms providing horses for one of the sales. On arrival at the events, shedding of EHV-1 was detected in 3.3%, EHV-4 in 1.1%, and EIV in 0.8% of horses. EHV-1 was detected at low levels, and EHV-1 and EHV-4 detection was not associated with clinical disease. EIV was detected only in horses at a Thoroughbred sale, in association with an outbreak of respiratory disease traced back to regional farms. On arrival at events, horses younger than 2 years had a significantly greater risk of shedding EHV-1 compared with older horses; no other significant risk factors associated with viral shedding were identified. Thus, there is a risk of exposure to EIV, EHV-1, and EHV-4 at equine events, and horses and events should be managed to mitigate this risk.  相似文献   

7.
AIM: 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), equine adenovirus 1 (EAdV-1), equine arteritis virus (EAV), reovirus 3 and parainfluenza virus type 3 (PIV3).

RESULTS: Viruses were isolated from 24/94 (26%) nasal swab samples and from 77/80 (96%) PBL samples collected from both healthy horses and horses showing clinical signs of respiratory disease. All isolates were identified as EHV-2, EHV-4, EHV-5 or untyped EHV. Of the horses and foals tested, 59/82 (72%) were positive for EHV-1 and/or EHV-4 serum neutralising (SN) antibody on at least one sampling occasion, 52/82 (63%) for EHV-1-specific antibody tested by enzyme-linked immunosorbent assay (ELISA), 10/80 (13%) for ERAV SN antibody, 60/80 (75%) for ERBV SN antibody, and 42/80 (53%) for haemagglutination inhibition (HI) antibody to EAdV-1. None of the 64 serum samples tested were positive for antibodies to EAV, reovirus 3 or PIV3. Evidence of infection with all viruses tested was detected in both healthy horses and in horses showing clinical signs of respiratory disease. Recent EHV-2 infection was associated with the development of signs of respiratory disease among yearlings [relative risk (RR)=2.67, 95% CI=1.59-4.47, p=0.017].

CONCLUSIONS: Of the equine respiratory viruses detected in horses in New Zealand during this study, EHV-2 was most likely to be associated with respiratory disease. However, factors other than viral infection are probably important in the development of clinical signs of disease.  相似文献   

8.
A survey was developed to examine the perception of equine practitioners regarding the occurrence of five equine neurologic diseases in the northeastern United States over the 10-year period between June 1, 1997 and June 1, 2007. This information was then compared with trends at Cornell University's Equine Hospital during the same time span, which in general agreed with practitioners' opinions. Equine herpes virus-1 (EHV-1) neurologic disease, equine motor neuron disease (EMND), and equine protozoal myelitis (EPM) have historic and current relevance. Results showed that the frequency of EMND and EPM has remained relatively stationary or decreased somewhat, whereas the frequency of the neurologic strain of EHV-1 may have increased slightly over the last decade. Less historical information on clinical disease associated with Borrelia burgdorferi infection (Lyme disease) and Parelaphostrongylus tenuis exists; however, results suggest that P. tenuis in the equine is presently emergent. Opinions regarding the existence and rate of occurrence of clinical borreliosis in horses appear divided. A better understanding of the frequency with which these diseases occur, as well as possible associated positive risk factors, will aid the equine practitioner in making an appropriate diagnosis in cases of neurologic disease in their equine patients.  相似文献   

9.
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10.
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 goal was to study: (1) Dissemination of virus following acute infection, (2) Development and frequency of ocular lesions following infection, and (3) Utility of a GFP-expressing virus for localization of the virus in vivo. Viral antigen could be detected following acute infection in ocular tissues and the central nervous system (experiment 1). Furthermore, EHV-1 infection resulted in multifocal choroidal lesions in 90% (experiment 2) and 50% (experiment 3) of experimentally infected horses, however ocular lesions did not appear in vivo until between 3 weeks and 3 months post-infection. Taken together, the timing of the appearance of lesions and their ophthalmoscopic features suggest that their pathogenesis may involve ischemic injury to the chorioretina following viremic delivery of virus to the eye, mirroring the vascular events that result in EHM. In summary, we show that the frequency of ocular EHV-1 is 50-90% following experimental infection making this model attractive for testing future vaccines or therapeutics in an immunologically relevant age group.  相似文献   

11.
Equine coital exanthema (ECE) is an acute, venereal disease caused by equid herpesvirus 3 (EHV-3), characterized by the formation of papules, vesicles, pustules, and ulcers on the vaginal and vestibular mucosa as well as on the skin of the penis, prepuce, and perineal region of mares and stallions. The present work describes an outbreak of ECE characterized by typical lesions around the anus and on the perineal skin, discomfort, and anorectal lymphadenopathy, which occurred in a large number of donor and recipient mares at an embryo transfer center in Argentina. We found that the horses' movement pattern, the environmental conditions, and the management procedures could have favored the introduction and/or reactivation from latency and spread of EHV-3. Although this is the first report of an outbreak of ECE in an embryo transfer facility, it reinforces the need to introduce additional hygienic and preventive measures to avoid EHV-3 spread and future ECE outbreaks.  相似文献   

12.
Background: Because of the serious disease sequelae associated with equine herpesvirus type 1 (EHV‐1) infections, awareness and control measures used to control outbreaks are important issues for all horse populations. Objectives: Describe the occurrence and management of an outbreak of EHV‐1 infection at a veterinary hospital. Animals: Horses hospitalized at a referral veterinary hospital. Methods: A horse with myeloencephalopathy associated with EHV‐1 infection (EHM) was admitted for diagnostic evaluation and treatment under strict infection control procedures. We describe the occurrence and management of a nosocomial outbreak of EHV‐1 infections associated with admission of this patient. Results: Despite institution of rigorous biosecurity precautions at the time of admission of the index case, EHV‐1 infections spread to 6 other horses that were hospitalized at the James L. Voss Veterinary Teaching Hopsital, including 2 that served as sources of infection for horses on their home premises after discharge. Infection with EHV‐1 was confirmed by polymerase chain reaction (PCR) and by seroconversion documented by glycoprotein G ELISA. A voluntary quarantine was imposed and admissions were restricted to prevent additional horses from being exposed. Quarantine duration was abbreviated by serial testing of all horses with PCR. Conclusions and Clinical Importance: These findings illustrate the contagious disease risk that can accompany management of horses with EHM. Horses with active nasal EHV‐1 shedding should be isolated in an airspace that is separate from other horses by strictly enforced biosecurity and isolation procedures. Serial testing with PCR may be a useful adjunct to determine when the risk of transmission has been minimized.  相似文献   

13.
Equine herpesvirus type-1 (EHV-1) and equine arteritis virus (EAV) are infectious agents that cause serious health risks to horse populations and are disbursed worldwide, which can lead to significant financial losses. In addition to being responsible for abortion and neonatal death, these viruses are associated with respiratory illness. Although previous research and reviews have been written on these viruses, both viruses still affect horse populations around the world and the vaccines currently available are not completely protective, especially against EHV-1 and equine herpes myeloencephalopathy (EHM). Moreover, EAV is considered a threat to the $102 billion equine industry in the United States. As a result, these viruses represent a huge threat to the horse industry and efforts geared towards preventing the outbreak of the disease are strongly encouraged. For this reason, updates about these viruses are necessary and require more and more discussion on the nature and characteristics of these viruses to know how to overcome them. Prevention and control of abortion and neonatal foal death caused by each of the two viruses depend on appropriate management strategies coupled with prophylactic vaccination. This review presents the latest detailed information on EHV-1 and EAV from several aspects such as transmission, clinical signs, pathogenesis, latest developments on the treatment of the diseases, vaccination, and finally challenges and future perspectives. The information presented herein will be useful in understanding EHV-1 and EAV and formulating policies that can help to limit the spread of these viruses within horse populations.  相似文献   

14.
Aim. To report the first isolation of equine herpesvirus 5 (EHV-5) in New Zealand as part of a study of equine respiratory viruses in New Zealand.

Methods. Nasal swabs and peripheral blood leukocytes were collected from 114 foals and adult horses, inoculated on to equine fetal kidney, rabbit kidney and Vero cell lines and observed for cytopathic effect. EHV-5 isolates were identified using an EHV-5 specific polymerase chain reaction. All samples positive for EHV-5 were also checked for the presence of EHV-2, EHV-1 or EHV-4 DNA using published type-specific primers. The polymerase chain reaction results were further confirmed by dot blot and Southern hybridisation with specific DIG-labelled probes.

Results. EHV-5 was isolated from nasal swabs or peripheral blood leukocytes of 38 out of 114 horses sampled. From horses sampled more than once, EHV-5 was often isolated on more than one occasion. Most of the horses were infected with both EHV-2 and EHV-5 viruses. It was not possible to make an association between EHV-5 isolation and the presence of respiratory disease.

Conclusion. EHV-5 is present in the New Zealand horse population. The exact role it plays in causing, or predisposing to, respiratory disease remains to be elucidated.  相似文献   

15.
试验旨在建立马疱疹病毒1型（Equine herpesvirus type1,EHV-1）人工发病模型,确定EHV-1感染马的半数感染量（ID50）及感染发病的判定标准,为该病的预防与治疗药物的研发奠定基础。以新疆伊犁地区某发病马场流产胎儿中分离的EHV-1 XJ2015株为研究对象,设立4组不同病毒剂量感染组及对照组,经鼻内喷雾感染马,5 mL/匹,每天观察试验马的临床症状和发病情况,14 d后进行剖检,观察各组织脏器病理变化并应用实时荧光定量PCR方法检测鼻腔排毒及病毒分布情况。结果显示,EHV-1 XJ2015株感染马的ID50为10-6.67/5 mL,其病毒含量为104.33 TCID50/mL。与对照组相比,1×106和1×105 TCID50/mL感染组马临床评分显著升高,主要表现为体温升高（高达39.5 ℃,一般持续2~6 d）、食欲不振、流浆液性鼻液和下颌淋巴结肿大;且1×106和1×105 TCID50/mL感染组试验马均表现出不同程度的排毒,肺脏及脑组织中可检测出大量病毒,与对照组相比极显著或显著升高（P<0.01;P<0.05）;病理学检查发现,患马脑组织出现非化脓性脑炎及神经元水肿,肺脏组织出现间质性肺炎、嗜中性粒细胞、炎性细胞浸润、出血和肺泡间隔增厚。以上结果表明,EHV-1 XJ2015株对马具有较强的致病性,患病马临床症状典型,病毒主要随鼻液排出,并富集在肺脏及脑组织,通过上述指标确定EHV-1感染马发病的判定标准,本试验成功建立EHV-1感染本体动物疾病模型。  相似文献   

16.
Infection with Equid Herpesvirus type 1 (EHV-1) leads to respiratory disease, abortion, and neurological disorders in horses. Molecular epidemiology studies have demonstrated that a single nucleotide polymorphism (A2254/G2254) in the genome region of the open reading frame 30 (ORF30), which results in an amino acid variation (N752/D752) of the EHV-1 DNA polymerase, is significantly associated with the neuropathogenic potential of naturally occurring strains. In order to estimate the prevalence of the EHV-1 neuropathogenic genotype in our country, we analyzed the ORF30 genome region of Argentinean EHV-1 isolates. The study was carried out by real time allelic discrimination PCR in 90 equine EHV-1-positive samples, being 89 from 54 cases of abortion outbreaks (two of which were in association with neurological disease) and one from the respiratory tract of a healthy horse in training. Our results indicate that 7% (4/54) of the abortion outbreaks studied were induced by the neuropathogenic (G2254) genotype of EHV-1 and 50% (2/4) of them were associated with simultaneous neurological disease. This information emphasizes the necessity to extreme the hygienic and preventive measures to diminish EHV-1 infections and consequently reduce the risk of epizootic neurological disease as has been recently observed in other countries.  相似文献   

17.
Equine herpesvirus type 1 (EHV-1) replicates extensively in the epithelium of the upper respiratory tract, after which it can spread throughout the body via a cell-associated viremia in mononuclear leukocytes reaching the pregnant uterus and central nervous system. In a previous study, we were able to mimic the in vivo situation in an in vitro respiratory mucosal explant system. A plaquewise spread of EHV-1 was observed in the epithelial cells, whereas in the connective tissue below the basement membrane (BM), EHV-1-infected mononuclear leukocytes were noticed. Equine herpesvirus type 4 (EHV-4), a close relative of EHV-1, can also cause mild respiratory disease, but a cell-associated viremia in leukocytes is scarce and secondary symptoms are rarely observed. Based on this striking difference in pathogenicity, we aimed to evaluate how EHV-4 behaves in equine mucosal explants. Upon inoculation of equine mucosal explants with the EHV-4 strains VLS 829, EQ(1) 012 and V01-3-13, replication of EHV-4 in epithelial cells was evidenced by the presence of viral plaques in the epithelium. Interestingly, EHV-4-infected mononuclear leukocytes in the connective tissue below the BM were extremely rare and were only present for one of the three strains. The inefficient capacity of EHV-4 to infect mononuclear cells explains in part the rarity of EHV-4-induced viremia, and subsequently, the rarity of EHV-4-induced abortion or EHM.  相似文献   

18.
CASE HISTORY AND CLINICAL FINDINGS: On 9 January 2014 (Day 0) a mare from a stud farm in the Waikato region presented with urinary incontinence without pyrexia. Over the following 33 days 15 mares were clinically affected with neurological signs. All but one mare had a foal at foot. The most commonly observed clinical signs were hind limb paresis and ataxia. In some cases recumbency occurred very early in the course of disease and seven mares were subject to euthanasia for humane reasons.

LABORATORY FINDINGS: Equid herpesvirus (EHV) type 1 was detected using PCR in various tissues collected post mortem from two mares with neurological signs. DNA sequencing data from the DNA polymerase gene of the virus showed a nucleotide transition at position 2254, a mutation encoding amino acid D752 that is highly associated with the neuropathogenic genotype of EHV-1. In total 12/15 mares were confirmed positive for EHV-1 on PCR. Results from a virus neutralisation test and ELISA on paired serum samples, and PCR on whole blood and nasal swabs, indicated that of four paddocks in a high-risk area where a cluster of cases had occurred, 20/21 (95%) horses were likely to have been exposed or were confirmed infected with EHV-1. Subsequent to the outbreak two mares aborted, one at 9 months and one at 10 months of gestation. The cause of abortion was confirmed as EHV-1 with the same genotype as that involved in the outbreak.

DIAGNOSIS: Equine herpesvirus myeloencephalopathy.

CLINICAL RELEVANCE: The outbreak described shows the considerable impact that can occur in outbreaks of equine herpesvirus myeloencephalopathy in New Zealand. Early biosecurity controls not only reduced the effect on the farm but mitigated the potential for the virus to spread to other horse enterprises.  相似文献   


19.
Background: Early identification of inhalation-transmitted equine herpesvirus type 1 (EHV-1) infections has been facilitated by the availability of a number of real-time quantitative PCR (qPCR) tests. A direct comparison between nasal swab qPCR and traditional virus isolation (VI) requires a method for normalizing the qPCR samples and controlling for PCR inhibitors present in some clinical samples.
Objectives: To quantify EHV-1 shedding in viral swabs using an internal control and to compare fast qPCR to VI for the detection of EHV-1 in nasal swabs from horses.
Animals: Fifteen horses experimentally infected with EHV-1.
Methods: Experimental study : Nasal swab samples were collected daily after experimental infection for up to 21 days. VI was performed by conventional methods. The DNA was prepared for qPCR with the addition of a known quantity DNA of Marek's disease virus as an internal control. qPCR was performed.
Results: The qPCR method detected virus up to day 21 after challenge, whereas VI detected virus only to day 5. The median Kaplan-Meier estimates for EHV-1 detection were 12 days for qPCR and 2 days for VI ( P < .0001). When compared with VI, the sensitivity and specificity of qPCR were 97 (95% CI: 86–100) and 27% (95% CI: 20–35).
Conclusions and Clinical Importance: We conclude that fast qPCR of nasal swab samples should be chosen for diagnosis and monitoring of herpesvirus-induced disease in horses. Recommended reference ranges of C T values are provided as well as justification of a minimum 10-day quarantine period.  相似文献   

20.
There has been an increase in outbreaks of neuropathogenic equine herpesvirus-1 (EHV-1) in the United States and Europe. However, the presence and frequency of neuropathogenic EHV-1 in Turkish horses are not known at present. This study aimed to investigate the frequency of EHV-1 and neuropathogenic strains of EHV-1 in the Marmara Region of Turkey. Samples were analyzed for the presence of EHV-1 and neuropathogenic EHV-1 by real-time PCR TaqMan probe assays. Overall detection rate of EHV-1 was 45.5% (51 of 112). The detection rates were 70.5% (24 of 34) in aborted fetuses, 53.3% (8 of 15) in neonatal deads, 66.6% (4 of 6) in foals, 40% (2 of 5) in dead mares, and 25% (13 of 52) in living mares. Overall detection rate of neuropathogenic EHV-1 was 7.8% (4 of 51), and the real-time PCR results were confirmed by sequencing. Neuropathogenic strains of EHV-1 were detected in the brain and lung of two mares with neurological disease but without a history of abortion, in the brain of a foal that died of respiratory disorder, and in the nasal swab from a mare with a history of abortion. On histopathology, nonpurulent meningoencephalitis, hemorrhages, and vasculitis were seen in the brain. In conclusion, results of this study indicated, for the first time, that the neuropathogenic EHV-1 is circulating in the Marmara Region of Turkey. The results of this study also show that the current risk for non-neuropathogenic strains is high, whereas risk for the neuropathogenic EHV-1-G2254 strain seems to be low. As outbreaks of EHV-1 continue in the Marmara region of Turkey, surveillance for neuropathogenic EHV-1 genotype should be maintained.  相似文献   

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