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Topic:Virus
The study of viral infections that affect equine species assesses the relationship between viruses and horses. Infections can lead to a range of clinical symptoms and may impact the health and performance of horses. Common equine viruses include Equine Influenza Virus, Equine Herpesvirus, and West Nile Virus, among others. Understanding the mechanisms of viral transmission, pathogenesis, and host immune responses is essential for developing effective prevention and treatment strategies. This page compiles peer-reviewed research studies and scholarly articles that explore the epidemiology, molecular biology, and clinical management of viral infections in horses.
Isolation and Characterization of Madariaga Virus from a Horse in Paraíba State, Brazil. Madariaga virus (MADV), the new species designation for the South American isolates of eastern equine encephalitis virus (EEEV), is genetically divergent and substantially different in ecology and pathogenesis from North American EEEV strains. We isolated and characterized a MADV isolate obtained from a horse in Brazil. Our results support previous phylogenetic studies showing there are three genetically distinct MADV lineages. The MADV isolate from Paraíba State belongs to the South American lineage III and is closely related to Peruvian, Colombian and Venezuelan isolates.
Complete Genome Sequences of Four African Horse Sickness Virus Strains from a Commercial Tetravalent Live Attenuated Vaccine. This is a report of the complete genome sequences of plaque-selected isolates of each of the four virus strains included in a South African commercial tetravalent African horse sickness attenuated live virus vaccine.
Prevalence factors associated with equine herpesvirus type 1 infection in equids with upper respiratory tract infection and/or acute onset of neurological signs from 2008 to 2014. The objective of the present case-control study was to determine prevalence factors associated with the detection of equine herpesvirus type 1 (EHV-1) by quantitative PCR (qPCR) in horses presented to veterinarians with clinical signs related to an upper respiratory tract infection and/or acute onset of neurological disease from March 2008 to December 2014. Nasal secretions and whole blood from 4228 equids with acute onset of fever, respiratory signs and/or neurological deficits were tested by qPCR for EHV-1. Categorical analyses were performed to determine the association between observations...
Sindbis and Middelburg Old World Alphaviruses Associated with Neurologic Disease in Horses, South Africa. Old World alphaviruses were identified in 52 of 623 horses with febrile or neurologic disease in South Africa. Five of 8 Sindbis virus infections were mild; 2 of 3 fatal cases involved co-infections. Of 44 Middelburg virus infections, 28 caused neurologic disease; 12 were fatal. Middelburg virus likely has zoonotic potential.
Pathology of Equine Influenza virus (H3N8) in Murine Model. Equine influenza viruses (EIV)-H3N8 continue to circulate in equine population throughout the world. They evolve by the process of antigenic drift that leads to substantial change in the antigenicity of the virus, thereby necessitating substitution of virus strain in the vaccines. This requires frequent testing of the new vaccines in the in vivo system; however, lack of an appropriate laboratory animal challenge model for testing protective efficacy of equine influenza vaccine candidates hinders the screening of new vaccines and other therapeutic approaches. In the present investigation, BALB/...
Association between inflammatory airway disease of horses and exposure to respiratory viruses: a case control study. Inflammatory airway disease (IAD) in horses, similar to asthma in humans, is a common cause of chronic poor respiratory health and exercise intolerance due to airway inflammation and exaggerated airway constrictive responses. Human rhinovirus is an important trigger for the development of asthma; a similar role for viral respiratory disease in equine IAD has not been established yet. Methods: In a case-control study, horses with IAD (n = 24) were compared to control animals from comparable stabling environments (n = 14). Horses were classified using pulmonary function testing and bronc...
Frequent presence of hepaci and pegiviruses in commercial equine serum pools. Novel viruses belonging to the genera Hepacivirus and Pegivirus have recently been discovered in horses and other animal species. Viral genomes of non-primate hepaciviruses (NPHV), equine pegivirus 1 (EPgV 1) and Theiler's disease associated virus (TDAV) were detected in a horse serum routinely used for cell culture propagation in our laboratory. Therefore, a study was carried out to further investigate the presence of these human Hepatitis C virus (HCV) related viruses in equine serum based products used in veterinary medicine and for research and to characterize the viral genomes. Without ex...
NS-gene based phylogenetic analysis of equine influenza viruses isolated in Poland. The phylogenetic analysis of influenza virus is based mainly on the variable hemagglutinin or neuraminidase genes. However, some discrete evolutionary trends might be revealed when more conservative genes are considered. We compared all available in GenBank database full length NS sequences of equine influenza virus including Polish isolates. Four nucleotides at positions A202, A237, T672 and A714 and three amino acids at positions H59, K71 and S216 which are also present in A/eq/Pulawy/2006 and A/eq/Pulawy/2008 may be discriminating for the Florida sublineage. Threonine at position 83 seems t...
Genetic variation and dynamics of infections of equid herpesvirus 5 in individual horses. Equid herpesvirus 5 (EHV-5) is related to the human Epstein-Barr virus (human herpesvirus 4) and has frequently been observed in equine populations worldwide. EHV-5 was previously assumed to be low to non-pathogenic; however, studies have also related the virus to the severe lung disease equine multinodular pulmonary fibrosis (EMPF). Genetic information of EHV-5 is scanty: the whole genome was recently described and only limited nucleotide sequences are available. In this study, samples were taken twice 1 year apart from eight healthy horses at the same professional training yard and samples f...
The first reported outbreak of equine herpesvirus myeloencephalopathy in New Zealand. 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. Results: Equid herpesvirus (EHV) type 1 was detected using PCR in various tissues collected post mortem from two mares with neurological signs...
Hepacivirus cross-species transmission and the origins of the hepatitis C virus. Just 5 years ago the hepatitis C virus (HCV) - a major cause of liver disease infecting >3% of people worldwide - was the sole confirmed member of the Hepacivirus genus. Since then, genetically-diverse hepaciviruses have been isolated from bats, dogs, cows, horses, primates and rodents. Here we review current information on the hepaciviruses and speculate on the zoonotic origins of the viruses in humans, horses and dogs. Recent and direct cross-species transmission from horses to dogs appears plausible, but the zoonotic origins of HCV in humans remain opaque. Mechanical transmission by biting ...
Mapping eastern equine encephalitis virus risk for white-tailed deer in Michigan. Eastern equine encephalitis (EEE) is a mosquito-borne viral disease that is often fatal to humans and horses. Some species including white-tailed deer and passerine birds can survive infection with the EEE virus (EEEV) and develop antibodies that can be detected using laboratory techniques. In this way, collected serum samples from free ranging white-tailed deer can be used to monitor the presence of the virus in ecosystems. This study developed and tested a risk index model designed to predict EEEV activity in white-tailed deer in a three-county area of Michigan. The model evaluates EEEV risk...
Identification of two phylogenetic lineages of equine hepacivirus and high prevalence in Brazil. Non-primate hepacivirus (NPHV), as described in horses, is the virus most genetically related to hepatitis C virus (HCV). Although detected worldwide, limited data on genomic variability and distribution of NPHV are available in Latin America. The aim of this study was to investigate the genetic diversity and prevalence of equine NPHV in Brazil. Thirteen percent of 202 equines from three Brazilian states were positive for NPHV genome by reverse transcriptase PCR. Nucleotide sequences of the partial NS5B genome presented the greatest diversity described to date (25.6%), which is comparable to t...
Routes of Hendra Virus Excretion in Naturally-Infected Flying-Foxes: Implications for Viral Transmission and Spillover Risk. Pteropid bats or flying-foxes (Chiroptera: Pteropodidae) are the natural host of Hendra virus (HeV) which sporadically causes fatal disease in horses and humans in eastern Australia. While there is strong evidence that urine is an important infectious medium that likely drives bat to bat transmission and bat to horse transmission, there is uncertainty about the relative importance of alternative routes of excretion such as nasal and oral secretions, and faeces. Identifying the potential routes of HeV excretion in flying-foxes is important to effectively mitigate equine exposure risk at the bat...
A review of traditional and contemporary assays for direct and indirect detection of Equid herpesvirus 1 in clinical samples. Equid herpesvirus 1 (EHV-1) is one of the most economically important equine viral pathogens. Its clinical manifestations in horses vary from acute upper respiratory tract disease, abortion, or neonatal death, to neurological disease termed equine herpesviral myeloencephalopathy, which may lead to paralysis and a fatal outcome. Successful identification of EHV-1 infection in horses depends on a variety of factors such as suitable case selection with emphasis on timing of sample collection, selection of appropriate sample(s) based on the clinical manifestations, application of relevant diagnost...
Enhanced sensitivity of an antibody competitive blocking enzyme-linked immunosorbent assay using Equine arteritis virus purified by anion-exchange membrane chromatography. In an effort to improve a competitive blocking enzyme-linked immunosorbent assay (cELISA) for antibody detection to Equine arteritis virus (EAV), antigen purified by anion-exchange membrane chromatography capsule (AEC) was evaluated. Virus purification by the AEC method was rapid and easily scalable. A comparison was made between virus purified by the AEC method with that obtained by differential centrifugation based on the following: 1) the relative purity and quality of EAV glycoprotein 5 (GP5) containing the epitope defined by monoclonal antibody 17B7, and 2) the relative sensitivity of a c...
Seroprevalence and factors associated with seropositivity to equine arteritis virus in Spanish Purebred horses in Spain. Equine viral arteritis (EVA), a disease caused by infection with the equine arteritis virus (EAV), is present in many European countries. In Spain, the last confirmed outbreak was reported in 1992 and there is a paucity of seroprevalence studies. The disease has a major impact on the equine breeding industry, which is mainly represented by Spanish Purebred (SP) horses in Spain. Objective: To estimate the seroprevalence of EAV in the breeding SP horse population in central Spain and identify potential horse and studfarm level factors associated with seropositivity to EAV. Methods: Cross-section...
Equine encephalosis in Thoroughbred foals on a South African stud farm. Thoroughbred foal body temperature data were collected from shortly after birth until shortly after weaning during the 2007/2008 season on a stud farm in the Western Cape Province of South Africa. Equine encephalosis (EE) caused by EE virus (EEV) serotype 4 (EEV-4) occurred in the foal group during the first autumn after their birth (March and April 2008). A descriptive study was undertaken to provide data on the EEV maternal antibody status, the association between pyrexia and EEV infection, and the incidence of infection amongst the foals prior to and during the episode. This included the fr...
Epidemiological and virological findings during multiple outbreaks of equine influenza in South America in 2012. In 2012, equine influenza (EI) virus was confirmed as the cause of outbreaks of respiratory disease in horses throughout South America. In Uruguay and Argentina, hundreds of vaccinated thoroughbred horses in training and racing facilities were clinically affected. Objective: To characterise the EI viruses detected during the outbreak in Uruguay and Argentina. Methods: Virus was detected in nasopharyngeal swabs by a pan-reactive influenza type A real-time RT-PCR. The nucleotide sequence of the HA1 gene was determined and analysed phylogenetically using mega 5 software. Amino acid sequences alig...
Landscape Utilisation, Animal Behaviour and Hendra Virus Risk. Hendra virus causes sporadic fatal disease in horses and humans in eastern Australia. Pteropid bats (flying-foxes) are the natural host of the virus. The mode of flying-fox to horse transmission remains unclear, but oro-nasal contact with flying-fox urine, faeces or saliva is the most plausible. We used GPS data logger technology to explore the landscape utilisation of black flying-foxes and horses to gain new insight into equine exposure risk. Flying-fox foraging was repetitious, with individuals returning night after night to the same location. There was a preference for fragmented arboreal ...
Multiple alignment comparison of the non-structural genes of three strains of equine influenza viruses (H3N8) isolated in Morocco. Three equine influenza viruses, A/equine/Nador/1/1997(H3N8), A/equine/Essaouira/2/2004(H3N8), and A/equine/Essaouira/3/2004(H3N8), were isolated from different Equidae during local respiratory disease outbreaks in Morocco in 1997 and 2004. Their non-structural (NS) genes were amplified and sequenced. Results: The results show high homology of NS nucleotide sequences of A/equine/Nador/1/1997 with European strains (i.e., A/equine/newmarket/2/93 and A/equine/Grobois/1/1998) and clustered into the European lineage. However, NS gene of A/equine/Essaouira/2/2004(H3N8) and A/equine/Essaouira/3/2004(H...
Analysis of the Association of Climate, Weather and Herd Immunity with the Spread of Equine Encephalosis Virus in Horses in Israel. It is claimed that the distribution of Culicoides-borne viruses is highly influenced by climate. Equine encephalosis virus (EEV) is a Culicoides-borne orbivirus which affects horses and was recently found to be endemic in Israel. To test whether climate is a crucial factor in the geographical distribution of EEV, we collected blood samples from horses in Israel during the years 2002, 2007 and 2010 and tested them for the abundance of antibodies to EEV. Samples were also collected in 2011 from horses that were seronegative to the virus in 2010, to determine the rate of infection with EEV. It wa...
Comprehensive Serology Based on a Peptide ELISA to Assess the Prevalence of Closely Related Equine Herpesviruses in Zoo and Wild Animals. Equine herpesvirus type 1 (EHV-1) causes respiratory disorders and abortion in equids while EHV-1 regularly causes equine herpesvirus myeloencephalopathy (EHM), a stroke-like syndrome following endothelial cell infection in horses. Both EHV-1 and EHV-9 infections of non-definitive hosts often result in neuronal infection and high case fatality rates. Hence, EHV-1 and EHV-9 are somewhat unusual herpesviruses and lack strict host specificity, and the true extent of their host ranges have remained unclear. In order to determine the seroprevalence of EHV-1 and EHV-9, a sensitive and specific pepti...
A High-Performance Multiplex Immunoassay for Serodiagnosis of Flavivirus-Associated Neurological Diseases in Horses. West Nile virus (WNV), Japanese encephalitis virus (JEV), and tick-borne encephalitis virus (TBEV) are flaviviruses responsible for severe neuroinvasive infections in humans and horses. The confirmation of flavivirus infections is mostly based on rapid serological tests such as enzyme-linked immunosorbent assays (ELISAs). These tests suffer from poor specificity, mainly due to antigenic cross-reactivity among flavivirus members. Robust diagnosis therefore needs to be validated through virus neutralisation tests (VNTs) which are time-consuming and require BSL3 facilities. The flavivirus envelop...
Complete genome sequences of T5-related Escherichia coli bacteriophages DT57C and DT571/2 isolated from horse feces. We report the complete genome sequencing of two Escherichia coli T5-related bacteriophages, DT57C and DT571/2, isolated from the same specimen of horse feces. These two isolates share 96% nucleotide sequence identity and can thus be considered representatives of the same novel species within the genus T5likevirus. The observed variation in the ltfA gene of these phages, resulting from a recent recombination event, may explain the observed host-range differences, suggesting that a modular mechanism makes a significant contribution to the short-term evolution (or adaptation) of T5-like phage gen...
Identification of a Novel Conserved B Cell Epitope in the N Protein of Equine Arteritis Virus (Bucyrus Strain). The nucleocapsid (N) protein is the most conserved structural protein in equine arteritis virus (EAV). This study aimed to identify the minimal conserved B cell epitope on the EAV N protein. The purified N protein was used to immunize mice for preparing monoclonal antibody (mAb). The reactivity of mAb was evaluated by Western blot and immunofluorescence assay. Moreover, 11 overlapping peptides (named MBP-N1 to MBP-N11) were designed to localize the linear antigenic epitope within the N protein. The peptides were identified by indirect enzyme-linked immunosorbent assay (ELISA) and Western blot....
Molecular Detection of Equine Herpesvirus Types 1 and 4 Infection in Healthy Horses in Isfahan Central and Shahrekord Southwest Regions, Iran. This study was undertaken to investigate molecularly the occurrence of EHV-1 and EHV-4 infection among equine population in regions, Iran. Blood samples from 53 and 37 randomly selected horses settled in Isfahan and Shahrekord, Iran, respectively, were collected. Detection of EHV-1 and EHV-4 genes in the blood samples was done using polymerase chain reaction (PCR). Out of 53 and 37 samples from Isfahan and Shahrekord, 4 (18.18%) and 3 (8.10%) were positive for PCR of EHV-1, respectively. Nine (16.98%) and 6 (16.21%) were positive for PCR of EHV-4, while 6 (11.32%) and 3 (8.10%) were positive f...
Vector-Host Interactions of Culiseta melanura in a Focus of Eastern Equine Encephalitis Virus Activity in Southeastern Virginia. Eastern equine encephalitis virus (EEEV) causes a highly pathogenic mosquito-borne zoonosis that is responsible for sporadic outbreaks of severe illness in humans and equines in the eastern USA. Culiseta (Cs.) melanura is the primary vector of EEEV in most geographic regions but its feeding patterns on specific avian and mammalian hosts are largely unknown in the mid-Atlantic region. The objectives of our study were to: 1) identify avian hosts of Cs. melanura and evaluate their potential role in enzootic amplification of EEEV, 2) assess spatial and temporal patterns of virus activity during a ...
Identification of G and P genotype-specific motifs in the predicted VP7 and VP4 amino acid sequences. Equine rotavirus (ERV) strain L338 (G13P[18]) has a unique G and P genotype. However, the evolutionary relationship of L338 with other ERVs is still unknown. Here whole genome analysis of the L338 ERV strain was independently performed. Its genotype constellations were determined as G13-P[18]-I6-R9-C9-M6-A6-N9-T12-E14-H11, confirming previous genotype assignments. The L338 strain only shared the P[18] and I6 genotypes with other ERVs. The nucleotide sequences of the other 9 RNA segments were different from those of cogent genes of all other group A rotavirus (RVA) strains including ERVs and fo...
