Virology in horses encompasses the study of viruses that affect equine species, including their biology, transmission, and impact on horse health. This field investigates viral pathogens that can lead to a range of diseases, from respiratory infections to neurological disorders. Common viruses affecting horses include equine influenza virus, equine herpesvirus, and West Nile virus. Understanding these viruses involves examining their genetic makeup, modes of transmission, and interactions with the equine immune system. This page compiles peer-reviewed research studies and scholarly articles that explore the epidemiology, pathogenesis, and control measures of viral infections in horses.
HARDY FM, ARBITER D.Hardy, Frank M. (Fort Detrick, Frederick, Md.), and David Arbiter. Lipid inclusions in L cells associated with Venezuelan equine encephalomyelitis virus infection. J. Bacteriol. 89:1101-1103. 1965.-Venezuelan equine encephalomyelitis (VEE) virus has been shown to induce changes of lipid components within the L cell. Lipid inclusions in the form of dark granular bodies were observed in the L cell after aqueous osmium tetroxide fixation and Sudan black staining. Microscopic examination of cells as early as 8 hr after infection with VEE virus showed an increase in the concentration of these inclu...
DITCHFIELD J, MACPHERSON LW.From outbreaks of upper respiratory infection of horses in the Toronto area between 1960 and 1963, several viruses have been isolated. The viruses, isolated in tissue cultures or eggs, include an equine strain of Myxovirus parainfluenzae 3; two strains of equine influenza virus, A/equi-1/Prague/56, and A/equi-2/Miami/63; equine rhinopneumonitis virus, and two newly recognized viruses of the horse, equine rhinoviruses. In addition serological evidence suggested a widespread infection with these viruses in the population under study. Because of the identical clinical picture seen and the complex...
Melnick JL, Hampil B.This paper summarizes the results of co-operative studies undertaken by the WHO International Reference Centre for Enteroviruses and a number of WHO Regional Reference Centres for viruses, WHO Virus Collaborating Laboratories, or other laboratories in a comprehensive testing programme of enterovirus equine antisera. The studies were designed to appraise the specificity of immune serum prepared in horses against five representative prototype enteroviruses (poliovirus 1, coxsackieviruses A9 and B3, and echoviruses 4 and 11). Tests for neutralizing antibody were performed not only against the hom...
CASALS J.A study by hemagglutination-inhibition test showed that 19 strains of eastern equine encephalitis virus grouped themselves in two main types, which have been designated North American and South American. The former consists of ten strains from the eastern half of the United States, from Massachusetts to Florida; Jamaica, the Dominican Republic, and, subject to confirmation, Thailand. The South American type comprises nine strains from Panama, Trinidad, British Guiana, Brazil, and Argentina. The strains were isolated from different natural hosts over a period of 30 years.
Marois P, Pavilanis V, Boudreault A, Di Franco E.The clinical diagnosis of equine influenza was first based on the spectacular contagiousness of the disease, the general clinical resemblances to human influenza and the almost complete absence of complications usually observed in infectious viral arteritis, viral rhinopneumonitis or in other respiratory infections of the horses. The specific viral etiology of the epizootic was ascertained through the isolation of a type A influenza virus and further substantiated by evaluation of the immunological response of the sick horses, as demonstrated by complement fixation and hemagglutination-inhibit...
DARLINGTON RW, RANDALL CC.Equine abortion virus was purified from the plasma of infected golden Syrian hamsters by differential centrifugation and nuclease treatment. The preparations were essentially free of nonviral elements on electron microscopic examination, and sedimentation in sucrose and potassium tartrate density gradients resulted in a single visible band. Electron microscopy of this band showed it to be composed of viral particles, and injection into hamsters resulted in infection and death of the animals. The viral particles had a sedimentation coefficient of approximately 2200 S and a hydrated density of 1...
PLUMMER G.Experiments involving the intranasal inoculation of monkeys, rabbits and guinea pigs with an equine respiratory virus were carried out. The animals were killed at various intervals after inoculation and attempts made to isolate virus in tissue culture from extracts of homogenized tissues and organs. All three species were susceptible, virus reproduction occurring in the respiratory tract and associated lymph glands. Of the three species virus was least readily isolated from the guinea pig tissues. There was a viraemia in monkeys and rabbits, but virus was less readily detected in the blood of ...
Nemoto M, Okita N, Kitahata M, Bannai H, Tsujimura K, Kinoshita Y, Kambayashi Y, Cullinane A, Yamanaka T, Ohta M.A rapid and sensitive diagnostic method is needed to help prevent the spread of equine influenza virus. The cobas Influenza A/B & RSV test for the cobas Liat system (Roche Diagnostics) is based on real-time reverse transcription polymerase chain reaction and is designed to broadly detect influenza A virus RNA within 20Â minutes. It detected a broad range of equine influenza virus strains, and detected equine influenza virus RNA from nasal swabs of infected horses at the same level as real-time reverse transcription polymerase chain reaction, although it returned some invalid results (7.7%)...
Razumov IA, Agapov EV, Pereboev AV, Protopopova EV, Lebedeva SD, Loktev VB.A comparative study of the antigenic structure of virulent strains and attenuated vaccine strains of Venezuelan equine encephalomyelitis virus (VEEV) by means of monoclonal antibodies has made it possible to investigate the antigenic structure of the envelope glycoproteins E1 and E2, and to specify their role in the development of antiviral immunity. On the E1 glycoprotein there are five nonoverlapping antigenic sites consisting of eight epitopes that are recognized by monoclonal antibodies; six sites consisting of twenty epitopes were found on the E2 glycoprotein. The monoclonal antibodies ag...
Kriegshäuser G, Cullinane A, Kuechler E, Skern T.Equine rhinitis B virus 1 (ERBV1), genus Erbovirus, family Picornaviridae, is a pathogen of horses which causes clinical and subclinical infection of the upper respiratory tract in horses. The virus is widespread in European horse populations and the current standard method for the detection of antibody against ERBV1 is by virus neutralisation (VN). VN tests, however, are labour-intensive and time-consuming, require tissue culture facilities, and generally do not provide same-day results. In this study, a protocol for the high-level expression and purification of recombinant virion protein 1 (...
Higashi T, Harasawa R.The three equine adenovirus strains isolated in different locations showed a similar cleavage pattern with HindIII and the DNA homology among the strains was confirmed by Southern blot hybridization. The three strains revealed differences in cleavage patterns with BamHI, EcoRI and PstI, suggesting the presence of DNA polymorphisms among equine adenoviruses.
Längerer L.Bernardino P, James K, Barnum S et al. What have we learned from 7 years of equine rhinitis B virus qPCR testing in nasal secretions from horses with respiratory signs. Vet Rec 2021; 188 (10): e26. DAS EQUINE RHINITIS-B-VIRUS (ERBV) HAT EINE HOHE INZIDENZ, IST IN SEINER BEDEUTUNG JEDOCH NUR WENIG ERFORSCHT. EINE INFEKTION MIT DEM ERBV äUßERT SICH IN SYMPTOMEN WIE FIEBER, ANOREXIE, LETHARGIE, NASENAUSFLUSS, HUSTEN, LYMPHADENOPATHIE UND ÖDEMEN DER DISTALEN GLIEDMAßEN. AUßERDEM TRETEN HäUFIG SUBKLINISCHE INFEKTIONEN AUF. DAS ZIEL DIESER STUDIE WAR, DIE HäUFIGKEIT DES NACHWEISES VON ERBV IM...
Urasawa S, Urasawa T, Ishizawa F, Taniguchi K.Bovine and equine sera were screened for poliovirus-reactive immunoglobulins (PRIgs) by means of neutralization and precipitation reactions with type 1 poliovirus. Bovine serum B1826 and B36 were found to contain such PRIgs from their reactivity to various PRIgs-resistant mutants of type 1 poliovirus origin. Neutralization and precipitation reactions with six mono-specific antibodies obtained by absorbing antiserum with each of the six different PRIgs-resistant virus mutants revealed that three antibodies were active in precipitation reaction while the others were substantially ineffective. On...
Iqbal J, Edington N.Equid herpesvirus 1 (EHV-1) is the most common cause of virus-induced abortion in horses. After primary infection the virus becomes latent predominantly in the respiratory tract lymph nodes and the genome can also be detected in the peripheral nervous system. The role of mouse as a feasible model for the establishment of latency and reactivation of EHV-1 was investigated. Intracerebral and intranasal infections of 3- and 17-day-old mice were made and virus replication was confirmed by virus isolation and detected by indirect immunofluorescence (IIF) in brain. For reactivation studies, the mice...
MacNeill AL, Micheloud JF, Parvin R, Gjessing M, Airas NA, Sant'Ana FJF, Adamek M.Zoonotic poxviruses, including monkeypox virus (MPV), the causative agent for Mpox disease, have gained significant media and scientific attention due to recent outbreaks in human populations across the globe. The increase in human cases of poxvirus infection is not unexpected, as routine vaccination against smallpox (a disease caused by the poxvirus variola virus, which cross protects against other orthopoxviruses) was discontinued in the 1980s after its eradication. Large numbers of vertebrate and invertebrate species are susceptible to infection by . Clinical signs and histologic lesions ca...
Rakaki ME, van der Walt M, Williams J, Venter M.We detected Shuni virus in horses and ovine fetuses and Shamonda virus in a caprine fetus in South Africa. We identified a Shuni/Shamonda virus reassortant in a horse and Shuni/Caimito, Shamonda/Caimito, and Shamonda/Sango virus reassortants in Culicoides midges. Continued genomic surveillance will be needed to detect orthobunyavirus infections in Africa.
Metz GE, Serena MS, Ocampos GM, Panei CJ, Fernandez VL, EcheverrÃa MG.Equine arteritis virus (EAV) was isolated from a testicle of the presumable first stallion infected with EAV in Argentina. This virus isolate (named LT-LP-ARG) was confirmed by GP5-specific PCR and indirect immunofluorescence assays. The PCR product was sequenced, and the phylogenetic analysis revealed that the LT-LP-ARG strain of EAV forms a monophyletic group, together with other strains previously isolated in our laboratory (LP02 group). However, all Argentinean EAV strains belong to a polyphyletic group. We believe that the virus isolate presented in this report could be the origin of EAV ...
Vanderstraeten E, Bogaert L, Bravo IG, Martens A.Squamous cell carcinoma (SCC) represents the most common malignant tumour of the eye and external genitals in horses. Comparable to humans, papillomaviruses (PV) have been proposed as etiological agents of cancer in horses and recently, Equine papillomavirus type 2 (EcPV2) has been identified in genital SCCs. Hitherto it had never been demonstrated in ocular SCCs. The first goal of this study was to determine the prevalence of EcPV2 DNA in tissue samples from equine genital and ocular SCCs, genital papillomas and penile intraepithelial neoplasia (PIN) lesions, using EcPV2-specific PCR. The sec...
Schröer U, Lange A, Glatzel P, Ludwig H, Borchers K.The aim of the present study was to clarify whether an EHV-1 induced abortion can be prognosticated by an increase of antibody titres, virus shedding and/or viraemia and whether the current abortion diagnostic is suitable. In this context the immune response post immunization and a possible reactivation were of great interest. For this purpose blood samples of 32 mares between the ages of 5-21 years were regularly investigated during a period of two years before and after vaccination and pregnancy. Neutralization tests, indirect immunofluorescence tests as well as PCR and virus isolation were ...
White SD, Foley JE, Spiegel IB, Ihrke PJ.Equine sarcoidosis is a rare, multisystemic, noncaseating, granulomatous and lymphoplasmacytic disease of unknown etiology. A recent report described a horse with granulomatous skin disease displaying histologic, electron microscopic, and polymerase chain reaction (PCR) findings consistent with equine herpesvirus 2 (EHV-2). Objective: To investigate the presence of EHV-2 and equine herpesvirus 1 (EHV-1) in 8 horses with sarcoidosis. Methods: Eight horses with sarcoidosis, reported previously. Methods: Retrospective study. PCR assays of the tissues were performed to detect DNA associated with E...
Starick E.Serum samples from 72 stallions were examined for the occurrence of antibodies against equine arteritis virus, of which 41 animals (57%) were found to be positive. 32 of the seropositive stallions were then screened for persistent EAV infection, before and after the breeding season. Semen samples were investigated by RT-PCR followed by dot blot hybridization and nested PCR, and by virus isolation on cell cultures as well. The carrier state was virologically confirmed in 11 of 32 stallions (34%) during the first and in 9 of 20 (45%) during the second investigation. RT-PCR followed by confirmato...
Marquardt J, Heymer J, Heinz H, Deegen E, Adolf GR, Leibold W.Interferon is known to induce antiviral mechanisms and to exert immunoregulatory capacities on various cell types. The antiviral capacity of recombinant equine interferon-beta 1 (rEqIFN-beta 1) is most sensitively monitored by indirect quantitation of multiplication of vesicular stomatitis virus (VSV) in blood cells of horses. As few as 0.5 pg rEqIFN-beta 1/ml can be assessed by means of 90% reduction of VSV-replication in whole blood (w.b.) as well as in isolated mononuclear blood cells (MNC) in spite of individual variations. The immunoregulatory influence of 20-50 pg rEqIFN-beta 1/ml is suf...
Thein P, Brown K.Infections with EHV1 can lead to manifestation at the CNS of horses followed by encephalomyelitis and "equine stroke". Horse experiments could confirm the clinical picture and gave links to the potential pathogenesis of the disease. We also have been in the position to isolate and characterize an EHV4 virus out of the brain of a horse with CNS disorders. The two viruses carry different biological properties which obviously dominate the pathogenesis. These properties as well as experimental and field cases are described and different diagnostic tests are discussed.
Denyer MS, Crowther JR.Antigenic differences within equine-1 and equine-2 isolates of influenza were studied by haemagglutination inhibition tests, indirect ELISA and competition ELISA, using the same antisera. Better differentiation was obtained with the competition ELISA than with the other two tests. All three methods produced similar relationships within the equine-1 isolates but differed in their ability to differentiate the equine-2 isolates where the competition ELISA was superior and produced epidemiologically sensible results. In all three tests, post-infection ferret and horse sera were more useful in disc...
Equine lentivirus receptor-1 (ELR1) has been characterized as the specific functional receptor that mediates equine infectious anemia virus (EIAV) entrance to horse macrophages. This receptor is tumor necrosis factor receptor superfamily member 14 (TNFRSF14). The aim of this study was to investigate the occurrence of allelic variants in the coding sequence of equine TNFRSF14 gene by screening for single-nucleotide polymorphisms (SNPs) in different equine populations. Forty seven horse samples were randomly selected from a reservoir of EIAV-seropositive and seronegative samples collected from d...
Liu L, Castillo-Olivares J, Davis-Poynter NJ, Baule C, Xia H, Belák S.Samples from horses experimentally infected with the "large plaque variant (LP3A+)" of equine arteritis virus were analysed. These included 182 nasal swabs collected from day 1 to 14 post-infection (p.i.), and 21 virus isolates obtained from white blood cells of animals that showed a prolonged viraemia between days 30 to 72 p.i. In order to determine the genetic stability of the virus and particularly to characterise the genetic variants found during the prolonged viraemia, partial sequences of open reading frame 5 (ORF5) encoding glycoprotein 5 (GP5) were generated. Viruses with amino acid su...
Jensen K.Examination of nasopharyngeal secretion and organ material from clinical cases of respiratory diseases in horses, using inoculation of embryonated hen eggs and rabbit and horse kidney cell cultures, resulted in the isolation of influenza virus and herpes virus. In 2 cases, both viruses were present in the same specimen. On the basis of the physio-chemical, cytological and serological criteria, the viruses were found to be identical with influenza virus type A equi 2 and herpes virus equi type 1. The methods for serological diagnosis and characterization of the influenza and herpes viruses are ...
Adam EN, Morley PS, Chmielewski KE, Carman J, Gonzales G.Because of the contagious nature of influenza virus it is necessary to identify infected individuals after the virus is introduced into a population. The aim of this study was to characterise influenza virus detection with commercially available assays after intranasal vaccinating horses with cold-adapted influenza virus. Seven horses were vaccinated and placed with 3 unvaccinated horses. Nasal secretion samples were evaluated using 2 antigen detection assays. All 10 horses were positive in the Flu OIA assay during the study period, but only one horse was positive on one sample using the Direc...
Bridges CG, Edington N.Equine sera were used to immunoprecipitate radiolabelled virus-infected cell proteins; subsequent resolution with polyacrylamide gel electrophoresis identified the EHV-1 polypeptides VP 2, 10a, 11, 13, 14, 15, 16, 20, 21 and 23a. The humoral support of ADCC by these sera was examined in vitro. Cytotoxicity could be demonstrated against both subtypes irrespective of the immunising isolate. The implications of these results are discussed.
Klingeborn B.Twelve mares were vaccinated with attenuated equine abortion virus (EAV) strain RAC-H. Two nonvaccinated mares served as controls. In at least three mares the vaccination appeared to coincide with a natural infection. This was indicated by characterization of the EAV isolated from nasal secretions of six vaccinated mares, a nonvaccinated control, and also from the lung, spleen, and liver of a fetus aborted by a vaccinated mare. The relative sensitivity of the isolated EAV to dithiothreitol was used to distinguish the RAC-H strain and wild-type virus. Of the 10 EAV isolates, four were recognize...
Morris CM, Field HJ.Tissue specimens obtained from equine herpesvirus-1 (EHV-1), subtype 1-infected aborted foetuses were analysed for the presence of virus DNA by means of Southern blot and dot blot hybridisations. The specificity of the methods was confirmed although the sensitivity was inferior to classical techniques such as virus isolation. However, the possibility of detecting the state of the virus DNA and the ability to distinguish between subtypes were important features, and the dot blot method was shown to have potential for a rapid diagnostic test. This report demonstrates some potential practical app...
Paweska JT, Henton MM, van der Lugt JJ.Clinical, virological and serological responses were evaluated in 10 pregnant mares after different challenge exposures to the asinine-94 strain of equine arteritis virus (EAV). The outcome of maternal infection on the progeny was also investigated. Mares were inoculated intranasally (n = 4), intramuscularly (n = 2), intravenously (n = 1), or contract-exposed (n = 3). All inoculated mares developed pyrexia, 5 showed mild clinical signs related to EAV infection and 2 remained asymptomatic. Viraemia was detected in all the inoculated animals and shedding of virus from the respiratory tract occur...
Ahmed SM, Broad SC, Edington N.Sera from two sibling groups of ponies experimentally infected with Equid herpesvirus 1 or 4 (EHV-1 or 4) were used to investigate which viral polypeptides (VPs) of EHV-1 and EHV-4 were recognised. Recognition was detected as early as 8 d.p.i. and thereafter. The polypeptides of EHV-1 (labelled with 35S-methionine) immunoprecipitated (IIP) by sera from both groups had Mr of 148, 138, 123, 117, 110, 77-79, 70, 55, 49-50, 47, 40 and 35-37 kDa respectively. Of these VP148K (VP9 nucleocapsid) gave the maximum precipitation, followed by 117 and 77-79 kDa. The latter were confirmed by monoclonal ant...
EcheverrÃa MG, DÃaz S, Metz GE, Serena MS, Panei CJ, Nosetto E.Equine viral arteritis (EVA) is a contagious viral disease that frequently causes mild or subclinical infections in adult horses. Only one EAV serotype has been described. However, there are differences in antigenicity, pathogenicity and neutralization characteristics of virus field strains. The interaction of two viral proteins, GP5 and M, is critical for infectivity and amino acid changes in the GP5 sequences have an effect on the neutralizing phenotype, regardless the effects of other viral proteins. The objective of the present study was to evaluate the neutralization phenotypes of the 5 u...
Kaaden OR, Truyen U.There is a continuous change in viral epidemics with respect to clinical symptoms, their duration or disappearance and the emergence of new diseases. This can be observed both in human and animal diseases. This evolution of virus diseases is mainly related to three factors: etiological agent, host and environment. As far as genetic alterations of the virus are concerned, two major mechanisms are involved: 1) mutations such as recombination and reassortment; 2) selection for resistance or susceptibility. The epidemiology of newly emerged virus diseases in man and animals, such as AIDS and hemor...
Raengsakulrach B, Staczek J.Equine cytomegalovirus (ECMV) contains a linear, double-stranded DNA genome composed of a 146-kbp unique region flanked by a pair of 18-kbp direct repeat (DR) sequences at the termini. Cycloheximide, actinomycin D, and phosphonoacetic acid were applied to infected cell cultures to divide viral transcription into immediate-early (IE), early, and late phases. Eight IE transcripts were identified and mapped to two regions (I and II) of the viral genome. Two of these IE RNAs (13.0 and 5.5 kb in size) were transcribed from region I, which is located within the DR regions; these IE genes are diploid...
