Detection of equid herpesviruses among different Arabian horse populations in Egypt

Molecular and Serological Investigation of Equine Herpesvirus Type 1 (EHV-1) and Type 4 (EHV-4) in Horses In Ibagué, Tolima

EHV-1 is one of the most prevalent viral pathogens in horses; however, its prevalence is not well defined by cross-reactions of serological tests. Thus, this study aims to determine EHV-1/-4 prevalence in Colombian creole horses from Ibagué, Tolima, using molecular techniques, as well as to determine possible risk factors associated with viral infection. A cross-sectional study was carried out in 110 equines blood, serum, and semen samples from Ibagué, Tolima. Antibodies against EHV-1/-4 were determined through indirect ELISA. EHV-1 was detected by amplifying the glycoprotein H gene through heminested PCR, and risk factors were calculated with chi-square, odds ratio, and fisher test. EHV-1/-4 antibodies were found in 11.8% of the horses. Moreover, the presence of EHV-1 and EHV-4 was determined in blood, serum, and semen of healthy clinical equines, with a prevalence infection in horses of 43.36% for EHV-1 and 2.7% for EHV-4. Sex, age, births number, abortions, natural breeding, and artificial insemination did not show significance as risk factors. This study determined a high prevalence of EHV-1 and low prevalence of EHV-4 in horses from Ibagué, Tolima. Furthermore, the possibility of finding the infectious agent in blood, serum, and semen was demonstrated. We recommend the use of blood and serum samples for virus detection and the development of new studies to assess EHV-1 infection feasibility in venereal transmissions.

Protective Role of Cepharanthine Against Equid Herpesvirus Type 8 Through AMPK and Nrf2/HO-1 Pathway Activation

Equid herpesvirus type 8 (EqHV-8) is known to cause respiratory disease and miscarriage in horses and donkeys, which is a major problem for the equine farming industry. However, there are currently limited vaccines or drugs available to effectively treat EqHV-8 infection. Therefore, it is crucial to develop new antiviral approaches to prevent potential pandemics caused by EqHV-8. This study evaluates the antiviral and antioxidant effects of cepharanthine against EqHV-8 by employing both in vitro assays and in vivo mouse models to assess its therapeutic efficacy. To assess the effectiveness of cepharanthine against EqHV-8, we conducted experiments using NBL-6 and RK-13 cells. Additionally, we developed a mouse model to validate cepharanthine's effectiveness against EqHV-8. In our in vitro experiments, we assessed the cepharanthine's ability to inhibit infection caused by EqHV-8 in NBL-6 and RK-13 cells. Our results demonstrated that cepharanthine has a dose-dependent inhibitory effect, indicating that it possesses anti-EqHV-8 properties at the cellular level. Moreover, we investigated the mechanism through which cepharanthine exerts its protective effects. It was observed that cepharanthine effectively reduces the oxidative stress induced by EqHV-8 by activating the AMPK and Nrf2/HO-1 signaling pathways. Furthermore, when administered to EqHV-8 infected mice, cepharanthine significantly improved lung tissue pathology and reduced oxidative stress. The findings presented herein collectively highlight cepharanthine as a promising candidate for combating EqHV-8 infections.

Molecular Detection of Equine Herpesviruses from Field Outbreaks in Donkeys in Northwest Amhara Region, Ethiopia

Equine herpesviruses pose a threat to equine health and potentially cause substantial economic losses to the global equine industry. EHV outbreaks have been reported in various parts of Ethiopia and the Amhara region specifically. This study aimed to detect EHVs from suspected outbreak cases in selected districts of the Northwest Amhara region. A cross-sectional study was performed from January 2022 to July 2022 to detect EHVs from suspected outbreak cases. Clinical observation was conducted for the presumptive identification of equine herpesvirus infection, and nasopharyngeal swab samples were collected for molecular detection of the viruses for confirmation. Out of 463 donkeys observed, 23 donkeys showed clinical signs suggestive of equine herpesvirus infection. Samples from 10 suspected donkeys were further subjected to polymerase chain reaction (PCR) test, amplifying ORF30 for EHV-1 and gB for EHV-2 and EHV-5. Among the 10 donkeys tested, seven (n = 7) were positive for EHV-5. All ten (n = 10) tested donkeys were negative for EHV-1 and EHV-2. EHV-5 was detected in animals with nervous signs, respiratory signs, a combination of nervous and respiratory signs, and a combination of abortion, respiratory, and nervous signs. Generally, only EHV-5 was identified from the outbreak, and more detailed epidemiological/molecular studies should be performed to better understand its dynamics and inform preventive measures.

Detection of equine herpesvirus antibodies in large-scale donkey farms in Liaocheng area

BACKGROUND

Equine herpesvirus (EHV) can cause respiratory, reproductive and neurological diseases in equine animals, including donkeys. The main pathogens responsible for these diseases are EHV type 1 (EHV-1) and EHV-4. In this study, we collected serum samples from 230 donkeys on 27 large-scale donkey farms to detect EHV-1 and EHV-4 antibodies. We analyzed the presence of EHV antibodies based on region, age and season.

RESULTS

Out of the 27 farms, 62.96% (17/27) tested positive for EHV. Of the 230 donkeys tested, 2.61% (6/230) were positive only for EHV-1, 5.22% (12/230) were positive only for EHV-4, and 4.78% (11/230) were positive for both EHV-1 and EHV-4. The highest percentage of positive donkeys (21.28%) was found in Dong'e County. The seropositivity rate among donkeys aged 1-4 years was significantly higher compared to the group of donkeys aged 0-1 year (p < 0.05). Additionally, the positive rate was significantly higher in fall and winter compared to spring and summer (p < 0.05).

CONCLUSIONS

Altogether, our findings indicate that large-scale donkey farms in the Liaocheng area have a high prevalence of EHV antibodies. Since Liaocheng is an important donkey trading market in Shandong Province, it is crucial to consider the risk of disease transmission based on our test results. This will help in early detection and prevention of EHV outbreaks.

Unmasking the ongoing challenge of equid herpesvirus- 1 (EHV-1): A comprehensive review

Equid herpesviruses (EHVs) are a group of highly impactful viral pathogens that affect horses, presenting a substantial risk to the global equine industry. Among these, equid herpesvirus-1 (EHV-1) primarily causes respiratory infections. However, its ability to spread to distant organs can lead to severe consequences such as abortion and neurological diseases. These viruses can enter a dormant phase, with minimal activity, and later reactivate to trigger active infections at any time. Recently, there has been a notable rise in the prevalence of a particularly devastating strains of EHV-1 known as equid herpesviral myeloencephalopathy (EHM). In the light of dynamic nature of EHV-1, this review provides a thorough overview of EHV-1 and explores how advances in viral biology affect the pathophysiology of viral infection. The information presented here is crucial for understanding the dynamics of EHV-1 infections and creating practical plans to stop the virus's global spread among equid populations.

Development of a live attenuated vaccine candidate for equid alphaherpesvirus 1 control: a step towards efficient protection

Equid alphaherpesvirus 1 (EqAHV1) is a viral pathogen known to cause respiratory disease, neurologic syndromes, and abortion storms in horses. Currently, there are no vaccines that provide complete protection against EqAHV1. Marker vaccines and the differentiation of infected and vaccinated animals (DIVA) strategy are effective for preventing and controlling outbreaks but have not been used for the prevention of EqAHV1 infection. Glycoprotein 2 (gp2), located on the envelope of viruses (EqAHV1), exhibits high antigenicity and functions as a molecular marker for DIVA. In this study, a series of EqAHV1 mutants with deletion of gp2 along with other virulence genes (TK, UL24/TK, gI/gE) were engineered. The mutant viruses were studied in vitro and then in an in vivo experiment using Golden Syrian hamsters to assess the extent of viral attenuation and the immune response elicited by the mutant viruses in comparison to the wild-type (WT) virus. Compared with the WT strain, the YM2019 Δgp2, ΔTK/gp2, and ΔUL24/TK/gp2 strains exhibited reduced growth in RK-13 cells, while the ΔgI/gE/gp2 strain exhibited significantly impaired proliferation. The YM2019 Δgp2 strain induced clinical signs and mortality in hamsters. In contrast, the YM2019 ΔTK/gp2 and ΔUL24/TK/gp2 variants displayed diminished pathogenicity, causing no observable clinical signs or fatalities. Immunization with nasal vaccines containing YM2019 ΔTK/gp2 and ΔUL24/TK/gp2 elicited a robust immune response in hamsters. In particular, compared with the vaccine containing the ΔTK/gp2 strain, the vaccine containing the ΔUL24/TK/gp2 strain demonstrated enhanced immune protection upon challenge with the WT virus. Furthermore, an ELISA for gp2 was established and refined to accurately differentiate between infected and vaccinated animals. These results confirm that the ΔUL24/TK/gp2 strain is a safe and effective live attenuated vaccine candidate for controlling EqAHV1 infection.

Rapid taxonomic categorization of short, abundant virus sequences for ecological analyses

Public health concerns about recent viral epidemics have motivated researchers to seek novel ways to understand pathogen infection in native, wildlife hosts. With its deep history of tools and perspectives for understanding the abundance and distribution of organisms, ecology can shed new light on viral infection dynamics. However, datasets allowing deep explorations of viral communities from an ecological perspective are lacking. We sampled 1086 bats from two, adjacent Puerto Rican caves and tested them for infection by herpesviruses, resulting in 3131 short, viral sequences. Using percent identity of nucleotides and a machine learning algorithm (affinity propagation), we categorized herpesviruses into 43 operational taxonomic units (OTUs) to be used in place of species in subsequent ecological analyses. Herpesvirus metacommunities demonstrated long-tailed rank frequency distributions at all analyzed levels of host organization (i.e., individual, population, and community). Although 13 herpesvirus OTUs were detected in more than one host species, OTUs generally exhibited host specificity by infecting a single core host species at a significantly higher prevalence than in all satellite species combined. We describe the natural history of herpesvirus metacommunities in Puerto Rican bats and suggest that viruses follow the general law that communities comprise few common and many rare species. To guide future efforts in the field of viral ecology, hypotheses are presented regarding mechanisms that contribute to these patterns.

A Screening Study Identified Decitabine as an Inhibitor of Equid Herpesvirus 4 That Enhances the Innate Antiviral Response

Equid herpesvirus 4 (EHV-4) is a common respiratory pathogen in horses. It sporadically induces abortion or neonatal death. Although its contribution in neurological disorders is not clearly demonstrated, there is a strong suspicion of its involvement. Despite preventive treatments using vaccines against EHV-1/EHV-4, the resurgence of alpha-EHV infection still constitutes an important threat to the horse industry. Yet very few studies have been conducted on the search for antiviral molecules against EHV-4. A screening of 42 antiviral compounds was performed in vitro on equine fibroblast cells infected with the EHV-4 405/76 reference strain (VR2230). The formation of cytopathic effects was monitored by real-time cell analysis (RTCA), and the viral load was quantified by quantitative PCR. Aciclovir, the most widely used antiviral against alpha-herpesviruses in vivo, does not appear to be effective against EHV-4 in vitro. Potential antiviral activities were confirmed for eight molecules (idoxuridine, vidarabine, pritelivir, cidofovir, valganciclovir, ganciclovir, aphidicolin, and decitabine). Decitabine demonstrates the highest efficacy against EHV-4 in vitro. Transcriptomic analysis revealed the up-regulation of various genes implicated in interferon (IFN) response, suggesting that decitabine triggers the immune antiviral pathway.

Seroprevalence and associated risk factors of equine herpesvirus type-1/-4 in selected districts of Northwest Amhara, Ethiopia

This study aimed to estimate the prevalence, determine the distribution, and identify the epidemiological risk factors of EHV-1/-4 infections in selected districts of Northwest Amhara Region. 460 serum samples were collected from equines using multistage cluster sampling technique, and a competitive Enzyme-linked immunosorbent assay (cELISA) was performed. Various risk factors for the occurrence of EHV-1/-4 were considered. Statistical analysis was performed using R version 4.3.1. 65.9% (303) equids were tested positive for antibodies against EHV-1/-4. Based on district, the highest prevalence was recorded in Wogera (86.1%), while the lowest was in Debark (47.4%). There was a significant difference (p <0.05; 95% CI: 1.1067993-3.682843) in the prevalence of EHV-1/-4 among species and donkeys are 2.019 times more likely to get an EHV infection than horses. The prevalence of EHV-1/-4 was highest in equids with the age of 3-8 years and lowest in < 3 years, and the difference was statistically significant (p <0.05; 95% CI: 1.9812042-6.771820). Statistically significant variation (p <0.05; 95% CI: 1.1173822-2.684013) was also observed between sex of equids in which females had 1.73 times higher chance to get EHV infection than males. Higher prevalence was found in lactating equids (81.6%), followed by pregnant equids (74.6%), and dry equids (66.4%). Generally, this study indicated a high and wide distribution of EHV-1/-4 infection in the study area, which needs due attention. Devising strategies to prevent and minimize the spread and occurrence of the infection is crucial.

Molecular characterization of equine herpes viruses type 1 and 4 among Arabian horse populations in Egypt during the period between 2021 and 2022

Background

Equine herpesvirus type 1 (EHV-1) is a major cause of abortion and respiratory disease. Equine herpesvirus type 4 (EHV-4), on the other hand, is exclusively associated with respiratory disease in horse populations worldwide, particularly in Egypt and Arabian countries.

Aim

This study aims to investigate the circulation of EHV-1 and EHV-4 in the Arabian horse population through molecular detection and genetic characterization of EHV-1 and/or EHV-4 that may threaten the stability of horse industry.

Methods

A total of 80 samples including 50 nasal swabs, 10 vaginal swabs and 20 whole blood samples were collected from vaccinated and registered pure-bred Arabian adult horses from different studs in the governorates of northern Egypt (Cairo, Dakahlyia and Qalyubia) from 2021 to 2022. The collected samples were screened using consensus PCR for detection of EHVs using specific primers targeting DNA polymerase gene. The positive samples were subjected to conventional PCR for detection of EHV-1 and/or EHV-4using specific primers targeting glycoprotein (gB) gene. EHV-1 and EHV-4 amplicons were partially sequenced and phylogenetically analyzed using Sanger method.

Results

Consensus PCR revealed that 48 out of 80 samples were positive for EHVs with percentage of 60%. Typing of the selected positive samples using conventional PCR showed that 29 out of 80 were positive for EHV-1 with percentage 36.25%, while 24 out of 80 samples were positive for EHV-4 with percentage 30%. Mixed infections with both viruses were detected in five samples. The amplified products were sequenced using Sanger method and submitted to GenBank under accession number OM362231MG-1 for EHV-1 strain and OM362232 MG-4 for EHV-4 strain. Sequence analysis and alignments of the amplified fragments of the EHV-1 and EHV-4 glycoprotein B (gB) gene to that of GenBank-derived reference strains revealed a high degree of similarity. According to the phylogenetic tree, the obtained sequences of EHV-1 and 4 in the current study showed homogeneity with local Egyptian and foreign EHV-1 and 4 strains and heterogeneity with EHV-2 and 5.

Conclusion

The current investigation showed that molecular methods are appropriate assays for an efficient and accurate diagnosis of EHVs. Furthermore, it supports earlier research findings about the prevalence of EHV-1 and 4 in Arabian horse populations in Egypt.

Recent sequencing and phylogenetic analysis of equine herpesviruses 1 and 4 among different equine populations in Egypt

Objective

Equine herpes viruses (EHVs) are considered one of the most important respiratory pathogens in equids, resulting in serious outcomes for equine health worldwide. The objectives of the current research were the detection, molecular characterization, and isolation of EHV-1 and EHV-4 circulating within different equine populations in Egypt, either clinically or in apparently healthy horses.

Material and Methods

A total of 120 field samples were collected, and DNA was extracted. Screening and typing of extracted DNA were done by consensus and conventional PCR assays for detection of EHV-1 and EHV-4, followed by sequencing and phylogenetic analysis to confirm the virus identity. Selected positive samples for both EHV-1 and EHV-4 were subjected to Madin-Darby bovine kidney (MDBK) cell lines for virus isolation.

Results

The obtained results revealed that 58/120 (48%) samples were positive for EHVs. Typing of positive samples showed that EHV-1 was detected in (48/120) 40% of samples and EHV-4 was detected in (15/120) 12% of samples, while dual infection by both EHV-1 and 4 was detected in five samples.

Conclusion

The current study revealed new data on the continuous circulation of EHV-1 and EHV-4 within equine populations in Egypt, and individual horses could be infected by multiple EHVs. In addition, latently infected horses are acting as potential reservoirs for frequent virus reactivation.

Serological Examinations of Significant Viral Infections in Domestic Donkeys at the Special Nature Reserve "Zasavica", Serbia

The paper presents the findings of specific antibodies in the blood sera of donkeys against the following viruses: equine infectious anemia virus (EIAV), African horse sickness virus (AHSV), equine herpesvirus type 1 (EHV-1), equine influenza virus subtype H3N8 (EIV) and equine arteritis virus (EAV). The analyses were conducted during the year 2022. From a total of 199 donkeys bred in "Zasavica", blood was sampled from 53 animals (2 male donkeys and 51 female donkeys), aged 3 to 10 years. Specific antibodies against EIAV were not detected in any of the tested animals using the agar-gel immunodiffusion (AGID) assay. No specific antibodies against AHSV, tested by enzyme-linked immunosorbent assay (ELISA), or antibodies against EAV, tested by the virus neutralization test (VNT) and ELISA were detected in any of these animals. A positive serological result for EHV-1 was determined by the VNT in all animals, with antibody titer values ranging from 1:2 to 1:128, while a very low antibody titer value for EIV (subtype H3N8) of 1:16 was determined in 18 donkeys using the hemagglutination inhibition test (HI test).

Potential outbreak by herpesvirus in equines: detection, clinical, and genetic analysis of equid gammaherpesvirus 2 (EHV-2)

BACKGROUND

Equid herpesvirus (EHV) commonly affects horses causing neurologic and respiratory symptoms beside spontaneous abortions, meaning huge economic losses for equine industry worldwide. In foals, the virus can facilitate secondary infections by Rhodococcus equi, important in morbidity and mortality in equines. A total of five genotypes of EHV were previously described in Brazil including EHV-1, EHV-2, EHV-3, EHV-4, and EHV-5. EHV-2 genotype had only been previously described in Brazil in asymptomatic animals. We report the investigation of the dead of 11 foals in Middle-west region of Brazil showing respiratory and neurological symptoms, as well as several abortions in mares from the same farm.

METHODS

Clinical and laboratory exams were performed in this case study. Lung, whole blood, serum, and plasma samples were analyzed by necroscopic and histopathologic techniques followed by molecular assays (conventional and qPCR and Sanger sequencing).

RESULTS AND CONCLUSION

Laboratory exams revealed neutrophilia leukocytosis. Necroscopic and histopathologic findings were suppurative bronchopneumonia and ulcerative enteritis. Molecular assays point to the absence of the bacteria Rhodococcus equi and other viruses (including other EHV). The presence of EHV-2 DNA was confirmed by sequencing in serum sample from one foal. This is the first confirmed outbreak of EHV-2 causing disease in Brazilian horses with confirmed presence of the virus, and which highlight the important role of EHV-2 in equine respiratory disease and spontaneous abortions in equid in Brazil.

Molecular characteristics and pathogenicity of an equid alphaherpesvirus 1 strain isolated in China

Equid alphaherpesvirus 1 (EHV-1) is prevalent in China, and causes notable economic damage to the equine industry. However, there is no information regarding the molecular characteristics and pathogenicity of the Chinese strains. Therefore, an EHV-1 strain, named YM2019, was isolated from the lung tissue of an aborted horse fetus in Xinjiang, China, and its genome and pathogenicity were analyzed. The full genome of the isolate was 150,267 base pairs in length, with 56.7% G + C content. Genetic and phylogenetic analysis showed that strain YM2019 (GenBank: MT063054) belonged to the ORF30 N752 genotype but displayed a high level of similarity with strain Ab4 (ORF30 D752, GenBank: AY665713) isolated in Britain. Fourteen unique amino acid mutations were found when comparing strain YM2019 with the reference strains Ab4 and V592 (ORF30 N752, GenBank: AY464052). Syrian hamsters infected with strain YM2019 exhibited severe respiratory and neurological clinical signs and died. Infection with strain YM2019 in Yili horses caused rhinopneumonitis, viremia, and neurological clinical signs such as hind limb lameness, prostration, and reduced movement. Here, we describe the features of an EHV-1 strain discovered in China, together with the complete genome sequence, and reveal that a nonneurovirulent strain (ORF30 N752) can also cause neurological signs in horses. The data will be useful in providing some reference for further research into the relationship between viral genotypes and pathogenicity.

AK-2011 strain for the development of a vaccine against equine rhinopneumonitis

Equine rhinopneumonitis is an acute, highly contagious disease found virtually worldwide. The purpose of the studies presented in this paper is to develop a technology for the manufacture of a cell-derived equine rhinopneumonitis vaccine, as well as to assess the safety and immunogenicity of the newly developed vaccine in laboratory animals model. The object of the studies was the AK-2011 strain isolated from the horses suffering from rhinopneumonitis during an outbreak of abortions. The viability of the AK-2011 strain was assessed using a continuous line of calf trachea cells, a continuous line of calf kidney cells, a continuous line of sheep kidney cells, a continuous line of bovine kidney cells, a continuous line of green monkey kidney cells, a continuous line of Syrian hamster kidney cells, a primary trypsinized culture of horse kidney cells grown in tubes and flasks, and the AK-2011 laboratory strain of equine rhinopneumonitis virus with biological activity of 6.0 lg TCID_50/cm ³ . Sequencing and polymerase chain reaction (PCR) analysis were performed. The virus isolated from the ORF68 gene in Kazakhstan appeared to be the most similar to the T-953 and 2222-03 strains isolated in the USA and Australia, respectively, in terms of phylogenetics. As to primary infections, cytopathic effects (CPE) induced by the AK-2011 virus stain (dilution 10¹ ) in calf trachea and horse kidney cell cultures were stable from the 1^st to 10^th passages, with biological activity of 5.75-6.00 lg TCID_50/cm ³ . CPE caused by the virus were apparent on days 2-3, further developed intensively, and extended to 60-80% of the cell monolayer on days 5-7. The vaccine results can be used to immunize horses on farms against rhinopneumonia, and horses should be immunized twice with an interval of 2-3 months. This article is protected by copyright. All rights reserved.

An Outbreak of Equine Herpesvirus-4 in an Ecological Donkey Milk Farm in Romania

Equine herpesviruses are important pathogens causing significant economic loss in equine and asinine populations. EHV-1/4 strains are mainly associated with respiratory distress. The aim of this study is to report the first EHV 4-associated respiratory disease in donkeys in Romania. Thirty-seven of three hundred jennies in an ecological donkey farm in southwest Romania started initially showing signs of severe upper respiratory tract disease, with ten concomitant late abortions/neonatal deaths and three neurological cases. There were nine fatalities. Pathological examination was performed, and samples were collected for Real-Time PCR analysis and histology. In addition, serum samples from 28 individuals with respiratory symptoms were collected and tested using indirect ELISA. RT-PCR identified the EHV-4 strain. Acute, diffuse necrotizing bronchointerstitial pneumonia with occasional intraepithelial intranuclear viral inclusion bodies was identified. Additionally, EHV-1/4-specific antibodies were found in 15 of the 28 sampled animals. Few studies on donkeys and herpesviruses have been published, and this is the first reported case of EHV-4 outbreak in Romania. There is a need for more extensive seroprevalence studies as, currently, the status of EHV-4 infection in donkeys in Romania is unknown.

Recent advancements in our understanding of equid gammaherpesvirus infections

Equid gammaherpesviruses are ubiquitous and widespread in the equine population. Despite their frequent detection, their contribution to immune system modulation and the pathogenesis of several diseases remains unclear. Genetic variability and the combination of equid gammaherpesvirus strains a horse is infected with might be clinically significant. Initial gammaherpesvirus infection occurs in foals peripartum with latency then established in peripheral blood mononuclear cells. A novel EHV-5 study suggests that following inhalation equid gammaherpesviruses might obtain direct access to T and B lymphocytes via the tonsillar crypts to establish latency. EHV-5 is associated with equine multinodular pulmonary fibrosis, however, unlike with EHV-2 there is currently minimal evidence for its role in milder cases of respiratory disease and poor performance. Transmission is presumed to be via the upper respiratory tract with periodic reactivation of the latent virus in adult horses. Stress of transport has been identified as a risk factor for reactivation and shedding of equine gammaherpesviruses. There is currently a lack of evidence for the effectiveness of antiviral drugs in the treatment of equine gammaherpesvirus infections.