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.
FEEMSTER RF.This research focuses on the first recognized human infection of equine encephalomyelitis, a disease mostly found in horses, which occurred in Massachusetts in the summer of 1938. The study dives […]
O'Keefe JS, Julian A, Moriarty K, Murray A, Wilks CR.A detection system incorporating the polymerase chain reaction was compared with the use of histopathology and virus isolation to determine the presence of equid herpesvirus type 1 or equid herpesvirus type 4 in equine tissues submitted to a diagnostic laboratory. When the polymerase chain reaction was performed, these tissues had been stored for up to 3 years. Thirty-eight tissues representing 14 cases had been stored embedded in paraffin wax. Analysis of these tissues using the PCR gave predictive values of 1.0 and 0.91 for a positive and negative result respectively, and sensitivity and spe...
Chirnside ED, Wearing CM, Binns MM, Mumford JA.cDNA copies of the M and N genes of equine arteritis virus (EAV) isolates were synthesized by reverse transcription followed by polymerase chain reaction amplification. The cDNA was subjected to a cycle sequencing strategy using Taq polymerase, and the nucleotide and derived amino acid sequences of 10 virus isolates were compared. The M and N genes of all isolates had the same initiation and termination sites as the prototype Bucyrus strain and the encoded proteins were conserved between viruses. Comparison of nucleotide sequence homologies and phylogenetic tree analysis implied the existence ...
Reisen WK, Meyer RP, Presser SB, Hardy JL.The extrinsic incubation rate (inverse of the time in days from infection to median transmission) of western equine encephalomyelitis (WEE) and St. Louis encephalitis (SLE) viruses by laboratory strains of Culex tarsalis Coquillett increased as a linear function of incubation temperatures from 10 to 30 degrees C. The estimated temperatures for zero transmission thresholds (intercept of the X axis) were 10.9 and 14.9 degrees C, and the number of degree days above these thresholds required for median transmission (inverse of the slope) was 67.6 and 115.2, respectively. Although the bodies of mos...
Marsh GA, Haining J, Hancock TJ, Robinson R, Foord AJ, Barr JA, Riddell S, Heine HG, White JR, Crameri G, Field HE, Wang LF, Middleton D.Hendra virus (HeV) is a highly pathogenic zoonotic paramyxovirus harbored by Australian flying foxes with sporadic spillovers directly to horses. Although the mode and critical control points of HeV spillover to horses from flying foxes, and the risk for transmission from infected horses to other horses and humans, are poorly understood, we successfully established systemic HeV disease in 3 horses exposed to Hendra virus/Australia/Horse/2008/Redlands by the oronasal route, a plausible route for natural infection. In 2 of the 3 animals, HeV RNA was detected continually in nasal swabs from as ea...
Becker W.From 1981 until 1987 we investigated the more detailed circumstances regarding a prophylactic vaccination in altogether 37 stud farms with a history of virus abortion. In 23 cases, in which Prevaccinol and/or Resequin were used, it was found that the following of vaccination schedule and necessary immunization programmes respectively, had considerable imperfections. In seven cases prophylactic vaccinations were not carried out or corresponding questionnaires were not answered. The fact that in the present data no case of virus abortion was observed, when the mare was vaccinated according to th...
Maclachlan NJ, Guthrie AJ.Arthropod-transmitted viruses (Arboviruses) are important causes of disease in humans and animals, and it is proposed that climate change will increase the distribution and severity of arboviral diseases. Orbiviruses are the cause of important and apparently emerging arboviral diseases of livestock, including bluetongue virus (BTV), African horse sickness virus (AHSV), equine encephalosis virus (EEV), and epizootic hemorrhagic disease virus (EHDV) that are all transmitted by haematophagous Culicoides insects. Recent changes in the global distribution and nature of BTV infection have been espec...
Sánchez MD, Pierson TC, Degrace MM, Mattei LM, Hanna SL, Del Piero F, Doms RW.A major neutralizing epitope (here referred to as the T332 epitope) located on the lateral surface of domain III (DIII) of the West Nile virus (WNV) envelope protein has been identified based on the analysis of murine monoclonal antibodies. However, little is known about the humoral immune response against WNV in a natural host or whether DIII in general or the T332 epitope in particular are important targets of neutralizing antibodies in vivo. To characterize the types of antibodies produced during infection with WNV, we studied a group of naturally infected horses. Using immune adsorption as...
Sabine M, Feilen C, Herbert L, Jones RF, Lomas SW, Love DN, Wild J.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...
Peel AJ, Field HE, Reid PA, Plowright RK, Broder CC, Skerratt LF, Hayman DT, Restif O, Taylor M, Martin G, Crameri G, Smith I, Baker M, Marsh GA....No abstract available
Dauphin G, Legay V, Pitel PH, Zientara S.For over two centuries, Borna disease (BD) has been described as a sporadically occurring infectious meningoencephalomyelitis affecting horses and sheep in Central Europe. Over the last decade, the BD epidemiology has been discussed. Firstly, its geographical distribution seems larger than what was previously thought. Secondly, the disease can affect a large number of warm-blooded animal species, including humans. The aetiological agent is the Boma disease virus (BDV), an enveloped, nonsegmented negative-stranded RNA virus classified in the new virus family Bornaviridae (Mononegavirales order)...
With outbreaks of equine influenza continuing to be reported in the UK, Richard Newton and Fleur Whitlock of the Animal Health Trust discusses practical steps that vets can promote and practise to reduce the risk of the virus spreading.
Bezerra CS, Cargnelutti JF, Sauthier JT, Weiblen R, Flores EF, Alves CJ, Clementino IJ, Santos CSAB, Azevedo SS.The aim of this survey was to estimate the apparent herd-level and animal-level prevalences, as well as to identify risk factors and spatial clustering of vesicular stomatitis virus (VSV) positive herds in the state of Paraíba, semiarid of Brazil. The state was divided into three sampling strata: Sertão, Borborema and Zona da Mata/Agreste. For each sampling stratum, herd-level and animal-level prevalences were estimated by a two-stage sampling survey. First, a pre-established number of herds (primary sampling units) were randomly selected; second, within each herd, a pre-established number o...
Cryz SJ.At the time the Swiss Serum and Vaccine Institute Berne (BERNA) was found in 1898, few vaccines or immune globulins were available. This short list included vaccines against cholera, typhoid fever, plague, smallpox and rabies and equine anti-tetanus and diphtheria immune globulins. Furthermore, their use was restricted due to limited production capacity, uncertainty regarding safety and no public health infrastructure to promote their utilization. Today, safe and effective vaccines exist for more than 30 infectious diseases while human hyperimmune globulins exist to treat or prevent rabies, te...
Middleton DJ, Weingartl HM.Hendra virus (HeV) and Nipah virus (NiV) form a separate genus Henipavirus within the family Paramyxoviridae, and are classified as biosafety level 4 pathogens due to their high case fatality rate following human infection and because of the lack of effective vaccines or therapy. Both viruses emerged from their natural reservoir during the last decade of the twentieth century, causing severe disease in humans, horses and swine, and infecting a number of other mammalian species. The current review summarizes our up to date understanding of pathology and pathogenesis in the natural reservoir spe...
Martín-Faivre L, Gaudaire D, Laugier C, Bouraïma-Lelong H, Zientara S, Hans A.Equine arteritis virus (EAV) is an Alphaarterivirus (family Arteriviridae, order Nidovirales) that frequently causes an influenza-like illness in adult horses, but can also cause the abortions in mares and death of newborn foals. Once primary infection has been established, EAV can persist in the reproductive tract of some stallions. However, the mechanisms enabling this persistence, which depends on testosterone, remain largely unknown. We aimed to establish an in vitro model of non-cytopathic EAV infection to study viral persistence. In this work, we infected several cell lines originating f...
Porphyre T, Grewar JD.African horse sickness (AHS) is a disease of equids that results in a non-tariff barrier to the trade of live equids from affected countries. AHS is endemic in South Africa except for a controlled area in the Western Cape Province (WCP) where sporadic outbreaks have occurred in the past 2 decades. There is potential that the presence of zebra populations, thought to be the natural reservoir hosts for AHS, in the WCP could maintain AHS virus circulation in the area and act as a year-round source of infection for horses. However, it remains unclear whether the epidemiology or the ecological cond...
van Schalkwyk A, Ferreira ML, Romito M.The outer capsid viral protein 2 (VP2) of African horse sickness virus, encoded by the most variable genome segment 2 (Seg-2), is the primary target for AHSV-specific neutralising antibodies and thus determines the virus serotype. Full length segment 2 sequences from more than 100 AHSVs isolated over the last 80 years were compared and single nucleotide polymorphisms (SNPs) identified between the reference strains and recent field viruses. Regions unique to each individual serotype were identified and primers designed to differentially amplify each of the nine serotypes. The sequences of resul...
Durán-Ferrer M, Agüero M, Zientara S, Beck C, Lecollinet S, Sailleau C, Smith S, Potgieter C, Rueda P, Sastre P, Monaco F, Villalba R....The laboratory diagnosis of African horse sickness (AHS) is important for: (a) demonstrating freedom from infection in a population, animals or products for trade (b) assessing the efficiency of eradication policies; (c) laboratory confirmation of clinical diagnosis; (d) estimating the prevalence of AHS infection; and (e) assessing postvaccination immune status of individual animals or populations. Although serological techniques play a secondary role in the confirmation of clinical cases, their use is very important for all the other purposes due to their high throughput, ease of use and good...
Marquardt J, Heymer J, Heinz H, Adolf GR, Deegen E.Recombinant equine interferon-beta 1 (reqIFN-beta 1) induces an antiviral state in blood mononuclear cells (BMC) of horses. Maximal protection against replication of vesicular stomatitis virus is achieved 6 hours after treatment with IFN in vitro and in vivo. Duration of the protective effect depends on the dose of IFN in vitro and in vivo. Availability of reqIFN-beta 1 in cultures of BMC for up to 48 hours does not prolong the antiviral state. The protective effect on BMC after treatment with IFN has similar duration in vivo and in vitro. Monitoring of the effect of IFN in vivo is, thus, simp...
Watson ED.The mechanisms that permit maternal tolerance of the conceptus allograft during early pregnancy in the mare have not been investigated. Embryos and endometria were collected from mares 14 days after ovulation and cultured for 20.5 h. The effect of addition of culture supernatant on incorporation of [3H]thymidine by equine peripheral blood lymphocytes was studied. Culture supernatant from endometrium of nonpregnant mares did not affect lymphocyte blastogenesis, but supernatant from both embryos and endometrium of pregnant mares reduced concanavalin A (Con A)- and phytohemagglutinin-induced blas...
Thomas DA, Furman PA.The reverse transcriptase of Equine Infectious Anemia Virus (EIAV) was partially purified from virus particles and appeared to be a heterodimer with subunit molecular masses of 70 kdal and 59 kdal. The polymerase activity of this enzyme had an absolute requirement for a divalent cation, preferring Mg++ over Mn++. Addition of a monovalent cation to the reaction mixture enhanced, but was not required for enzyme activity. Kinetically, the reverse transcriptase of EIAV is similar to the reverse transcriptase of Human Imunodeficiency Virus Type 1 (HIV-1). Both enzymes have similar Km values for 2'-...
Tåmová B, Stumpa A, Zakopal J, Vĕzníková D, Mensík J.Equine influenza occurred in Czechoslovakia 14 years after the last epizootic in horses that had returned from abroad. Six strains A (Heq1Neq1) antigenically related to, but not identical with, strain A/eq/Praha/56 were isolated from 10 washings. Seroconversion was demonstrated with paired sera, but the antibody increase was more marked against the newly isolated strain.
Ramsauer AS, Badenhorst M, Cavalleri JV.Equine parvovirus hepatitis (EqPV-H) was first described in 2018 in a fatal case of Theiler's disease which followed the administration of an equine-origin biological product. The virus has since been frequently identified in serum and liver tissue of horses affected by Theiler's disease-an acute, severe hepatitis characterised by fulminant hepatic necrosis with a fatal outcome in most cases. EqPV-H is hepatotropic, appears to be associated with subclinical to severe hepatitis in horses, and is a likely cause of Theiler's disease. Although this disease is most frequently reported following the...
Carossino M, Balasuriya UBR, Thieulent CJ, Barrandeguy ME, Vissani MA, Parreño V.Equine rotavirus A (ERVA) is the leading cause of diarrhea in foals, with G3P[12] and G14P[12] genotypes being the most prevalent. Recently, equine G3-like RVA was recognized as an emerging infection in children, and a group B equine rotavirus (ERVB) was identified as an emergent cause of foal diarrhea in the US. Thus, there is a need to adapt molecular diagnostic tools for improved detection and surveillance to identify emerging strains, understand their molecular epidemiology, and inform future vaccine development. We developed a quadruplex TaqMan RT-qPCR assay for differentiation of ERVA an...
Metz GE, Serena MS, Panei CJ, Nosetto EO, Echeverria MG.A semen sample from a stallion infected during the 2010 equine arteritis virus (EAV) outbreak was received for viral isolation prior to castration of the animal. The virus was identified using a polyclonal antibody immunofluorescence test. Reverse-transcription polymerase chain reaction (RT-PCR) was used to amplify a region of the GP5 gene with primers GL105F and GL673R. The PCR products were purified and sequences of both strands were determined in a MegaBACE™1000 with inner primers CR2 and EAV32. A phylogenetic dataset was built with the previously reported sequences of five strains isolat...
Ledbetter EC, Cutler TJ, Irby NL.The aim of this study was to describe the clinical, confocal microscopic, histologic, and virologic features of horses with macrodendritic ulcerative keratitis and conjunctival lymphoid hyperplasia associated with equine herpesvirus-2 and equine herpesvirus-5 infection. Methods: Four foals with bilateral ocular disease. Methods: Complete ophthalmic examination was performed for each horse, and corneal samples were collected for cytology and microbiologic evaluation, including virus isolation and molecular diagnostics for the equine herpesviruses. In vivo confocal microscopy examination of the...
Kunanusont N, Taesuji M, Kulthonggate U, Rattanamas K, Mamom T, Thongsri K, Phannithi T, Ruenphet S.African horse sickness (AHS) has become a newly emerging disease after an outbreak in northeastern Thailand in March 2020. Mass vaccination in horses with live-attenuated AHS virus (AHSV) vaccine is essential for AHS control and prevention. This study aimed to monitor the longitudinal humoral immune response before and after a single vaccination using a live-attenuated vaccine against AHS in stallions, mares, and pregnant mares, including maternal immunity in foals born from pregnant mares during the outbreak in Thailand. Unassigned: A total of 13 stallions and 23 non-pregnant and 21 pregnant ...
Sandybayev N, Strochkov V, Beloussov V, Orkara S, Kydyrmanov A, Khan Y, Batanova Z, Kassenov M.Equine influenza (EI) is a highly contagious disease that causes fever and upper respiratory tract inflammation. It is caused by influenza virus A, belonging to the family, with subtypes H3N8 and H7N7. This study presents data on the development of a real-time polymerase chain reaction (RT-PCR) assay using TaqMan probes to detect the H3 subtype of EI virus (EIV). Unassigned: The evaluation of the developed RT-PCR assay involved five strains of EIV as positive controls and ten nasopharyngeal swab samples collected from horses. RNA was isolated using the GeneJet Viral DNA and RNA Purification K...
Peters-Kennedy J, Löhr CV, Cossic B, Glaser AL, Duhamel GE.Equine herpesvirus-5 (EHV-5) is commonly found in healthy asymptomatic horses worldwide. Although a cause-and-effect relationship has not been thoroughly determined, this virus has been associated with several disease conditions including equine multinodular pulmonary fibrosis (EMPF) and 1 case of interface dermatitis. The authors searched the New York State Animal Health Diagnostic Center database for cases of equine interface dermatitis between 2007 and 2022. Ten cases were identified and scrutinized for viral inclusion bodies which were present in 5 of 10 cases. Two similar cases with inter...
