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.
Lian WC, Liau MY, Mao CL.Nervous disorders were found in two horses and verified as aseptic encephalitis by necropsy in the summer of 2000. To investigate agents that affected the horses, diagnostic procedures involving virus isolation, neutralization test and reverse transcription-polymerase chain reaction (RT-PCR) were performed. We intracranially inoculated litters of suckling mice with tissues suspected of containing aseptic encephalitis, including cerebrum, cerebellum, brain stem, thalamus, and cerebrospinal fluids; the mice were then observed for 14 days. Neutralizing antibodies against Japanese encephalitis (JE...
Storey ES, Gerding PA, Scherba G, Schaeffer DJ.To determine survival over time of infectious equine herpesvirus-4, feline herpesvirus-1, and feline calicivirus in three commercially available and commonly used ophthalmic solutions (eyewash, fluorescein, and proparacaine HCl). Methods: Viruses used in this study were originally isolated from eyes of animals referred to the University of Illinois. Equine herpesvirus-4 was propagated in MDBK cells and feline herpesvirus-1 and feline calicivirus in CRFK cells. Methods: After separately inoculating a designated solution with a specific titer of an individual virus, solutions were incubated per ...
Wu D, Murakami K, Liu N, Inoshima Y, Yokoyama T, Kokuho T, Inumaru S, Matsumura T, Kondo T, Nakano K, Sentsui H.The full-length equine interferon-gamma (eIFN-gamma) cDNA, including the secretion signal peptide coding region, was recloned into baculovirus transfer vector pAcYM1. This vector was co-transfected with Autographa californica nuclear polyhedrosis virus DNA or hybrid nuclear polyhedrosis virus DNA into Spodoptera frugiperda cells. The recombinant viruses, named AcEIFN-gamma and HyEIFN-gamma, were then recovered. Recombinant eIFN-gamma (reIFN-gamma) was accumulated in the culture fluid of the AcEIFN-gamma or HyEIFN-gamma infected Tricoplusia ni -derived cell line, BTI TN 5B1-4, and hemolymph of ...
Patel JR, Bateman H, Williams J, Didlick S.A German abortion isolate of EHV-1 (strain M8) was grown in equine dermal (ED) cells at a low multiplicity of infection in presence of 5-bromo-2-deoxy uridine. The resulting stock was dialysed, titrated and cloned by terminal dilution in ED cells grown in 96-well microtitration plates. Of 192 clones each originating from a single focus, clone 147 (C147) was found to be restricted for growth at and above temperatures of 38.5 degrees C. It was also restricted for growth at 37 degrees C in rabbit kidney (RK-13) cells which are widely used for the isolation and titration of EHV-1; hence clone 147 ...
Howe L, Leroux C, Issel CJ, Montelaro RC.Equine infectious anemia virus (EIAV) infection of horses is characterized by well-defined waves of viremia associated with the sequential evolution of distinct viral populations displaying extensive envelope gp90 variation; however, a correlation of in vivo envelope evolution with in vitro serum neutralization phenotype remains undefined. Therefore, the goal of the present study was to utilize a previously defined panel of natural variant EIAV envelope isolates from sequential febrile episodes to characterize the effects of envelope variation during persistent infection on viral neutralizatio...
Cook RF, Cook SJ, Li FL, Montelaro RC, Issel CJ.A single-tube reverse transcriptase-polymerase chain reaction (RT-PCR) using a fluorogenic real-time PCR detection method is described for the quantitation of equine infectious anemia virus (EIAV) RNA in the plasma of equids. To compensate for variations inherent in sample preparation a multiplex real-time RT-PCR system was developed that permitted the simultaneous calculation of the nucleic acid recovery rate along with the copy number of viral RNA molecules. Detection of EIAV RNA was linear from 10(9) to 10(1) molecules with intra- and inter-assay variability of less than 1% at 10(8), 10(6),...
Smith D, Hamblin A, Edington N.Antisera to activated equine endothelial cells, which detected surface molecules of 116 kD, 97 kD, 42 kD and 38 kD, were made to investigate the role of endothelial adhesion molecules in equid herpes virus 1 infection. These putative adhesion molecules could be induced by 17-beta oestradiol, chorionic gonadotrophin, or IL-2, as well as by LPS and PWM. In an in vitro flow system, using equine veins or arteries, equid herpesvirus 1 in leucocytes was only transferred to infect endothelial cells if both leucocytes and endothelial cells expressed these surface molecules. Blocking of the membrane mo...
Kleiboeker SB, Schommer SK, Johnson PJ, Ehlers B, Turnquist SE, Boucher M, Kreeger JM.Over a period of 6 years, antemortem and postmortem examinations were performed on a number of donkeys suffering from respiratory disease. For many cases, initial diagnostic efforts failed to identify an etiology consistent with the pathologic findings. However, retrospective examination of these cases using consensus primer polymerase chain reaction, designed to recognize herpesviruses from all 3 subfamilies of the Herpesviridae, amplified a fragment of the highly conserved herpesvirus DNA polymerase gene from a number of these animals. Two novel herpesviruses, herein designated asinine herpe...
Zhou W, Cook RF, Cook SJ, Hammond SA, Rushlow K, Ghabrial NN, Berger SL, Montelaro RC, Issel CJ.The env gene is an excellent candidate for inclusion in any DNA-based vaccine approach against equine infectious anemia virus (EIAV). Unfortunately, this gene is subjected to mutational pressure in E. coli resulting in the introduction of stop codons at the 5' terminus unless it is molecularly cloned using very-low-copy-number plasmid vectors. To overcome this problem, a mammalian expression vector was constructed based on the low-copy-number pLG338-30 plasmid. This permitted the production of full-length EIAV env gene clones (plcnCMVenv) from which low-level expression of the viral surface un...
Lazar A, Epstein E, Lustig S, Barnea A, Silberstein L, Reuveny S.Peptic cleavage of horse plasma IgG is a common procedure for the preparation of F(ab)(2) products for human use, such as antivenin and antitoxin. The removal of the Fc fragment from the IgG molecule by enzymatic cleavage at low pH, ensures fewer side-effects of the F(ab)(2) product for passive immunotherapy compared with the whole IgG molecule. Since the starting material may be contaminated by zoonotic horse viruses, it is necessary to demonstrate the removal or inactivation of possible viral contaminants. Guidelines for performing such studies were published by the Commission for Plasma-Der...
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...
van Maanen C, Cullinane A.Equine influenza is one of the most economically important contagious respiratory diseases of horses. In this paper the current state of knowledge of equine influenza virus and the most important aspects of these virus infections, e.g. epidemiology, clinical aspects, pathogenesis and pathology, immunity, diagnosis, treatment, management and vaccination, are reviewed with an emphasis on epidemiology, diagnosis and vaccinology. Many questions have remained and with the advent of improved technology new questions have arisen. Consequently, research priorities should be set in an attempt to answer...
Howell PG, Groenewald D, Visage CW, Bosman AM, Coetzer JA, Guthrie AJ.Selected isolates of equine encephalosis virus were shown to have comparable viral protein profiles and to represent seven distinct serotypes, based on cross-neutralization tests. Serotype-specific virus-neutralizing antibody in serum samples from horses confirmed the widespread occurrence of infection. The distribution and prevalence of individual serotypes however, varied considerably. Localised foci with an increased seasonal seroconversion in groups of horses to a specific serotype and the detection of an ongoing low level of infection from other serotypes within the population, confirmed ...
Moore BD, Balasuriya UB, Hedges JF, MacLachlan NJ.Equine viral arteritis (EVA) is an endotheliotropic viral disease of horses caused by equine arteritis virus (EAV). Although there is only one serotype of EAV, there is marked variation in the virulence of different strains of the virus. The replication and cytopathogenicity of three well-characterized strains of EAV of different virulence to horses were compared in rabbit kidney (RK-13) and primary equine pulmonary artery endothelial cells (ECs). Viral protein expression, plaque size, and cytopathogenicity of all three viruses were similar in RK-13 cells, whereas two virulent strains of EAV w...
McLean RG, Ubico SR, Bourne D, Komar N.WN virus is one of the most ubiquitous arboviruses occurring over a broad geographical range and in a wide diversity of vertebrate host and vector species. The virus appears to be maintained in endemic foci on the African continent and is transported annually to temperate climates to the north in Europe and to the south in South Africa. Reports of clinical disease due to natural WN virus infection in wild or domestic animals were much less common than reports of infection (virus isolation or antibody detection). Until recently, records of morbidity and mortality in wild birds were confined to ...
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...
Billich C, Sauder C, Frank R, Herzog S, Bechter K, Takahashi K, Peters H, Staeheli P, Schwemmle M.The recent observation that Borna disease virus (BDV)-reactive antibodies from psychiatric patients exhibit only low avidity for BDV antigen called into question their diagnostic value and raised the possibility that antigenically related microorganisms or self antigens caused the production of these antibodies. We further characterized the specificity of these antibodies. Methods: We established a peptide array-based screening test that allows the identification of antibodies directed against linear epitopes of the two major BDV proteins, the nucleoprotein (N) and the phosphoprotein (P). Resu...
Glaser AL, Renshaw RW, Trock SC, Brady RC, Dubovi EJ.Salem virus (SalV) is a recently identified equine virus belonging to the family Paramyxoviridae. The only known isolate was obtained from a horse that was involved in a disease outbreak of undetermined nature and the circumstances of its isolation suggested an etiologic role. However, the experimental infection of a colostrum-deprived foal failed to reproduce the disease; only mild neutropenia and temperature elevation were recorded. An additional attempt to establish an etiological relationship with the disease was made by conducting a retrospective evaluation of the serological profiles of ...
Jeronimo C, Archambault D.Equine arteritis virus (EAV), an enveloped positive-stranded RNA virus, is the prototype of the arterivirus group. In a previous paper (A. Kheyar, S. Martin, G. St.-Laurent, P. J. Timoney, W. H. McCollum, and D. Archambault, Clin. Diagn. Lab. Immunol. 4:648-652, 1997), we have shown that the unglycosylated membrane (M) protein, which is composed of 162 amino acids (aa), is a major target of equine antibody to EAV. In order to determine the antigenic regions of the M protein, the cDNA encoding the M protein of EAV was inserted into the procaryotic expression vector pGEX-4T-1 to produce recombin...
Bunning ML, Bowen RA, Cropp CB, Sullivan KG, Davis BS, Komar N, Godsey MS, Baker D, Hettler DL, Holmes DA, Biggerstaff BJ, Mitchell CJ.A total of 12 horses of different breeds and ages were infected with West Nile virus (WNV) via the bites of infected Aedes albopictus mosquitoes. Half the horses were infected with a viral isolate from the brain of a horse (BC787), and half were infected with an isolate from crow brain (NY99-6625); both were NY99 isolates. Postinfection, uninfected female Ae. albopictus fed on eight of the infected horses. In the first trial, Nt antibody titers reached >1:320, 1:20, 1:160, and 1:80 for horses 1 to 4, respectively. In the second trial, the seven horses with subclinical infections developed Nt a...
Learmonth GS, Love DN, Wellington JE, Gilkerson JR, Whalley JM.The unusual mucin-like high molecular mass (Mr) glycoprotein 2 (gp2) has only been described in the equid alphaherpesviruses, among which there is considerable antigenic cross-reactivity. Equine herpesvirus 1 (EHV-1) gp2 is cleaved into a highly glycosylated N-terminal subunit and a 42 kDa C-terminal cleavage product. In order to investigate their antigenic recognition by horses naturally infected with EHV-1 and/or equine herpesvirus 4 (EHV-4), the C-terminal cleavage product and high Mr gp2 were affinity purified. Cross-reactivity between EHV-1 and EHV-4 was observed for the high Mr gp2 using...
Iqbal J, Purewal AS, Edington N.The aim of this study was to investigate the role of immediate early gene (gene63) in the pathogenesis of equine herpesvirus 1 (EHV-1) acute and latent infections in equine and murine models. EHV-1 gene63 mutant virus (g63mut) along with EHV-1 (Ab4) was used for intracerebral and intranasal infection of 3 and 17-day-old mice. Both viruses were recovered at the same frequency from tissues after infection. Two Welsh ponies were infected via the intranasal route with each of the viruses. Acute infection was monitored by virus isolation from nasal swabs and peripheral blood leukocytes. Six weeks p...
Palombo EA.Rotaviruses are the major cause of severe gastroenteritis in young children and animals. The rotavirus genome is composed of eleven segments of double-stranded RNA and can undergo genetic reassortment during mixed infections, leading to progeny viruses with novel or atypical phenotypes. There are numerous descriptions of rotavirus strains isolated from human and animals that share genetic and antigenic features of viruses from heterologous species. In many cases, genetic analysis by hybridization has clearly demonstrated the genetic relatedness of gene segments to those from viruses isolated f...
Franklin RP, Kinde H, Jay MT, Kramer LD, Green EG, Chiles RE, Ostlund E, Husted S, Smith J, Parker MD.A yearling quarter horse, which was raised in southern California, received routine vaccinations for prevention of infection by Eastern equine encephalomyelitis virus (EEEV). One week later, severe neurologic signs developed, and the horse was humanely destroyed. A vaccine-related encephalomyelitis was later suspected. A final diagnosis of EEEV infection was established on the basis of acute onset of the neurologic signs, histopathologic and serologic testing, and isolation and molecular characterization of EEEV from brain tissue. The vaccine was extensively tested for viral inactivation. Nucl...
Kaaden OR, Eichhorn W, Essbauer S.There is continual variation in viral epidemics regarding clinical symptoms, duration and disappearance, and the emergence of new diseases. This can be observed in both human and animal diseases. This evolution of virus diseases is mainly related to three factors: aetiological agent, host and environment. As far as genetic alterations of the virus are concerned, two major mechanisms are involved: mutations such as recombination and reassortment; and selection for resistance or susceptibility. This review focuses on the epidemiology of newly emerged virus diseases in man and animals, such as ac...
Stierstorfer B, Eichhorn W, Schmahl W, Brandmüller C, Kaaden OR, Neubauer A.An outbreak of neurological disease occurred in a well-managed riding school. Ataxia and paresis were observed in several horses, five of which became recumbent and were euthanized. Post-mortem analysis revealed scattered haemorrhages along the spinal cord, that were reflected by multiple haemorrhagic foci on formalin-fixed sections, with the thoracic and lumbar segments being the most affected. Pathohistologically, perivascular mononuclear cuffing and axonal swelling, especially in the white matter, were evident. Parallel to the course of disease, alterations in myelin sheets and activation o...
Rudolph J, O'Callaghan DJ, Osterrieder N.The genome of equine herpesvirus type 1 (EHV-1) strain RacL11, a highly virulent isolate obtained from an aborted foal, and that of the modified live vaccine strain KyA, were cloned as bacterial artificial chromosomes (BAC) in Eseherichia coli. Mini F plasmid sequences were inserted into the viral genomes by homologous recombination instead of the gene 71 (EUS4) open reading frame after co-transfection of viral DNA and recombinant plasmid pdelta71-pHA2 into RK13 cells. After isolation of recombinant viruses by three rounds of plaque purification, viral DNA was isolated from RK13 cells infected...
Yilmaz H, Helps CR, Turan N, Uysal A, Harbour DA.The nucleoprotein of Borna disease virus (BDV-p40) was produced in a Baculovirus expression system using sf9 cells. The purity and specificity of the recombinant p40 was confirmed by SDS-PAGE and immunoblotting. The recombinant p40 was used in an ELISA to screen horse sera in Turkey. For this, 323 horses from selected cities in the Marmara region of Turkey were examined clinically and serum was collected from each. All horses were clinically healthy except for a few with wounds on the skin. Antibodies to BDV were detected in the sera of 82 (25%) of 323 horse sera. Six sera were selected that h...
van der Meulen KM, Nauwynck HJ, Pensaert MB.Equine herpesvirus-1 (EHV-1) is an important pathogen of horses, causing abortion and nervous system disorders, even in vaccinated animals. During the cell-associated viremia, EHV-1 is carried by peripheral blood mononuclear cells (PBMC), mainly lymphocytes. In vitro, monocytes are the most important fraction of PBMC in which EHV-1 replicates, however, mitogen stimulation prior to EHV-1 infection increases the percentage of infected lymphocytes. The role of the cell cycle in viral replication and the role of cluster formation in cell-to-cell transmission of the virus were examined in mitogen-s...
Bossart KN, Wang LF, Eaton BT, Broder CC.Hendra virus (HeV) is an emerging paramyxovirus first isolated from cases of severe respiratory disease that fatally affected both horses and humans. Understanding the mechanisms of host cell infection and cross-species transmission is an important step in addressing the risk posed by such emerging pathogens. We have initiated studies to characterize the biological properties of the HeV envelope glycoproteins. Recombinant vaccinia viruses encoding the HeV F and G open reading frames were generated and glycoprotein expression was verified by metabolic labeling and detection using specific antis...
Brindley MA, Zhang B, Montelaro RC, Maury W.Wild-type strains of equine infectious anemia virus (EIAV) prevent superinfection of previously infected cells. A variant strain of virus that spontaneously arose during passage, EIAV(vMA-1c), can circumvent this mechanism in some cells, such as equine dermis (ED) cells, but not in others, such as equine endothelial cells. EIAV(vMA-1c) superinfection of ED cells results in a buildup of unintegrated viral DNA and rapid killing of the cell monolayer. Here, we examined the mechanism of resistance that is used by EIAV to prevent superinfection and explored the means by which EIAV(vMA-1c) overcomes...
Durán-Ferrer M, Villalba R, Fernández-Pacheco P, Tena-Tomás C, Jiménez-Clavero MÁ, Bouzada JA, Ruano MJ, Fernández-Pinero J, Arias M....This study described the clinical, virological, and serological responses of immunologically naïve and vaccinated horses to African horse sickness virus (AHSV) serotype 9. Naïve horses developed a clinical picture resembling the cardiac form of African horse sickness. This was characterized by inappetence, reduced activity, and hyperthermia leading to lethargy and immobility-recumbency by days 9-10 post-infection, an end-point criteria for euthanasia. After challenge, unvaccinated horses were viremic from days 3 or 4 post-infection till euthanasia, as detected by serogroup-specific (GS) real...
Virmani N, Bera BC, Shanumugasundaram K, Singh BK, Gulati BR, Singh RK, Vaid RK.India faced an epizootic of equine influenza in 2008-2009. The isolated viruses were typed as H3N8 and grouped with the clade 2 viruses of Florida sublineage on the basis of haemagglutinin (HA) gene sequence analysis. This report describes the genetic analysis and selection pressure of matrix (M) and non-structural 1 (NS1) genes of the Indian isolates. All isolates shared 98.41% and 99.54% homology with other clade 2 viruses of Asian origin for M1 and M2 amino acid (aa) sequences, respectively. There were 3 and 4 unique aa residue changes respectively in M1 and M2 proteins in all Asian isolate...
Covaleda L, Gno BT, Fuller FJ, Payne SL.The macrophage-tropic lentivirus, equine infectious anemia virus (EIAV), encodes the small auxiliary protein S2 from a short open reading frame that overlaps the amino terminus of env EIAV S2 is dispensable for virus replication in cultured cells but is required for disease production. S2 is approximately 7 kDa and has no overall amino acid sequence homology to other cellular or viral proteins. Therefore it is likely that S2 plays a role as an adaptor protein. To further investigate S2 function we performed a yeast-2-hybrid screen to identify cellular proteins that interact with EIAV S2. The s...
Stone-Marschat M, Carville A, Skowronek A, Laegreid WW.Reverse transcription-PCR (RT-PCR) was used to detect African horse sickness virus (AHSV). A single primer pair which amplified a 423-bp fragment of the S8 gene which encodes the NS2 protein of AHSV was identified. Amplification of this fragment from all nine serotypes of AHSV was achieved with these primers. Between 10(1) and 10(2) copies of AHSV genomic double-stranded RNA could be detected by RT-PCR followed by agarose gel electrophoresis and ethidium bromide staining. Application of RT-PCR to blood samples from AHSV-infected horses resulted in earlier detection of viremia than virus isolat...
Allen LJ, Schwartz EJ.Equine infectious anemia virus (EIAV) is a lentivirus in the retrovirus family that infects horses and ponies. Two strains, referred to as the sensitive strain and the resistant strain, have been isolated from an experimentally-infected pony. The sensitive strain is vulnerable to neutralization by antibodies whereas the resistant strain is neutralization-insensitive. The sensitive strain mutates to the resistant strain. EIAV may infect healthy target cells via free virus or alternatively, directly from an infected target cell through cell-to-cell transfer. The proportion of transmission from f...
Dutta SK, Campbell DL.Equine macrophages from the mammary glands of a yearling filly and an 18-year-old barren nonlactatind mare formed cell monolayers in continuous cultures. There was absence of viral cytopathic effect (CPE) in early cell culture passages. The cells from the early cell culture passages having no CPE failed to show evidence of virus or viral antigen by electron microscopic and immunofluorescence studies. Foci of CPE first appeared in the monolayer cell cultures from the filly and the mare in the 3rd and the 4th serial passages respectively, and the CPE increased on subsequent serial passages. Equi...
Chambers TM, Reedy SE.Serologic tests for equine influenza virus (EIV) antibodies are used for many purposes, including retrospective diagnosis, subtyping of virus isolates, antigenic comparison of different virus strains, and measurement of immune responses to EIV vaccines. The hemagglutination-inhibition (HI), single radial hemolysis (SRH), and serum micro-neutralization tests are the most widely used for these purposes and are described here. The presence of inhibitors of hemagglutination in equine serum complicates interpretation of HI assay results, and there are alternative protocols (receptor-destroying enzy...
Nemoto M, Niwa H, Murakami S, Miki R, Higuchi T, Bannai H, Tsujimura K, Kokado H.Equine group A rotaviruses (RVAs) cause diarrhoea in foals. We investigated the G genotypes of 360 RVA-positive samples obtained from diarrhoeic foals between 2012 and 2018 in the Hidaka district of Hokkaido, Japan, through sequence analysis of VP7. All samples were classified into genotypes G3A, G3B and G14. G3B RVAs were detected until 2016, and G3A RVAs were detected from 2016 to 2018. G14 RVAs were detected from 2012 to 2018. Although G3B RVAs had been circulating in Japan for a long time, G3A RVAs suddenly emerged in 2016, and have replaced G3B RVAs since 2017. Molecular analyses of VP7 a...
Evermann JF.Retroviral infections of livestock have become of increasing importance due to their usefulness as comparative models for human retroviral infections and their effects upon animal health and marketability of animals and animal products nationally and internationally. This paper presents a perspective on the retroviruses of economic concern in veterinary medicine with emphasis on the importance of understanding the modes of virus transmission and the species specificity of the viruses. The retroviruses reviewed include the oncovirus, bovine leukosis virus, and the lentiviruses, equine infectiou...
Zhang J, Miszczak F, Pronost S, Fortier C, Balasuriya UB, Zientara S, Fortier G, Timoney PJ.Genetic variation and phylogenetic relationships among 22 French isolates of equine arteritis virus (EAV) obtained over four breeding seasons (2001-2004) were determined by sequencing open reading frames (ORFs) 2a-7. The ORFs 2a-7 of 22 isolates differed from the prototype virulent Bucyrus strain of EAV by between 14 (99.5% identity) and 328 (88.7% identity) nucleotides, and differed from each other by between 0 (100% identity) and 346 (88.1% identity) nucleotides, confirming genetic diversity among EAV strains circulating in France. Phylogenetic analysis based on the partial ORF5 sequences (n...
Yamanaka T, Bannai H, Nemoto M, Tsujimura K, Kondo T, Matsumura T.In 2010, the World Organisation for Animal Health recommended the inclusion of a Florida sublineage clade2 strain of equine influenza virus (H3N8), which is represented by A/equine/Richmond/1/07 (Richmond07), in equine influenza vaccines. Here, we evaluate the antigenic differences between Japanese vaccine strains and Richmond07 by performing hemagglutination inhibition (HI) assays. Ferret antiserum raised to A/equine/La Plata/93 (La Plata93), which is a Japanese vaccine strain, reacted with Richmond07 at a similar titer to La Plata93. Moreover, two hundred racehorses exhibited similar geometr...
Ji Y, Guo W, Zhao L, Li H, Lu G, Wang Z, Wang G, Liu C, Xiang W.An antigen-capture enzyme-linked immunosorbent assay (AC-ELISA) was developed for the detection of the equine influenza virus (EIV), employing monoclonal and polyclonal antibodies against the A/equine/Xingjiang/2007 (H3N8) nucleoprotein (NP). Immunoglobulin G antibodies were purified and used as capture or detector antibodies. The specificity of the optimized AC-ELISA was evaluated using EIV, equine herpesvirus 1 (EHV-1), equine herpesvirus 4 (EHV-4), equine arteritis virus (EAV) and Japanese encephalitis virus (JEV), resulting in only EIV specimens yielding a strong signal. A minimal concentr...
Piyasena TBH, Setoh YX, Hobson-Peters J, Prow NA, Bielefeldt-Ohmann H, Khromykh AA, Perera D, Cardosa MJ, Kirkland PD, Hall RA.In Australia, infection of horses with the West Nile virus (WNV) or Murray Valley encephalitis virus (MVEV) occasionally results in severe neurological disease that cannot be clinically differentiated. Confirmatory serological tests to detect antibody specific for MVEV or WNV in horses are often hampered by cross-reactive antibodies induced to conserved epitopes on the envelope (E) protein. This study utilized bacterially expressed recombinant antigens derived from domain III of the E protein (rE-DIII) of MVEV and WNV, respectively, to determine whether these subunit antigens provided specific...
Mankoc S, Hostnik P, Grom J, Toplak I, Klobucar I, Kosec M, Barlic-Maganja D.In the present study, a new one-step real-time reverse transcription-polymerase chain reaction (RT-PCR) strategy with minor-groove-binder (MGB) technology for the detection of EAV from 40 semen samples of Slovenian carrier stallions was tested. A novel MGB probe (EAVMGBpr) and a reverse primer (EAV-R) based on the multiple sequence alignment of 49 different EAV strain sequences of the highly conserved ORF7 (nucleocapsid gene) were designed. The performance of the assay was compared with different molecular detection methods. Three different primer pairs targeting the ORF1b and ORF7 were used, ...
Ghanem YM, Fukushi H, Ibrahim ES, Ohya K, Yamaguchi T, Kennedy M.Viruses related to equine herpesvirus type 1 (EHV-1) were isolated from an aborted fetus of an onager (Equus hemionus) in 1984, an aborted fetus of Grevy's zebra (Equus grevyi) in 1984 and a Thomson's gazelle (Gazella thomsoni) with nonsuppurative encephalitis in 1996, all in the USA. The mother of the onager fetus and the gazelle were kept near plains zebras (Equus burchelli). In phylogenetic trees based on the nucleotide sequences of the genes for glycoproteins B (gB), I (gI), and E (gE), and teguments including ORF8 (UL51), ORF15 (UL45), and ORF68 (US2), the onager, Grevy's zebra and gazell...
Hasebe R, Kimura T, Nakamura K, Ochiai K, Okazaki K, Wada R, Umemura T.Equine herpesvirus 1 (EHV-1) shows endotheliotropism in the central nervous system (CNS) of infected horses. However, infection of endothelial cells has not been observed in the CNS of infected mice. To explore the basis for this difference in endotheliotropism, we compared the susceptibility of equine brain microvascular endothelial cells (EBMECs) and mouse brain microvascular endothelial cells (MBMECs) to EHV-1 infection. The kinetics of viral growth in EBMECs was typical of a fully productive infection whereas viral infection in MBMECs seemed to be nonproductive. Immunofluorescence microsco...
Venter GJ, Groenewald D, Venter E, Hermanides KG, Howell PG.Equine encephalosis virus (EEV) is widespread and prevalent in southern Africa. In this study, the oral susceptibility of Culicoides (Avaritia) imicola Kieffer (Diptera: Ceratopogonidae) to EEV was confirmed. In addition, C. (A.) bolitinos Meiswinkel, collected in the high-lying eastern Free State, South Africa, was systemically infected with the Bryanston serotype of EEV after feeding through a membrane on artificially infected equine blood containing 4.7 log10 PFU/mL of EEV. The mean infectivity of Bryanston virus in C. bolitinos increased from 1.2 log10 PFU/midge, in midges assayed for viru...
Munday JS, Hardcastle MR, Sim M.A 10-year-old horse presented with two 3-cm diameter exophytic masses over the fetlock. Histology was consistent with a hyperplastic squamous papilloma and numerous cell changes consistent with papillomavirus (PV) infection were visible. Partial sequences of PV L1 and E1 ORFs were amplified using consensus PCR primers. The sequences were most similar to Equus caballus type 1 (EcPV1). However, as the sequences were only around 73% similar to EcPV1, they appear to be from a novel PV type that is likely to be within the genus. The papillomas were treated with topical imiquimod and resolved withi...
Rosas CT, Goodman LB, von Einem J, Osterrieder N.Infections of horses with equine herpesvirus type 1 (EHV-1) have garnered new attention over the last few years. Devastating outbreaks occurring worldwide, primarily of the neurologic form of the disease, have resulted in a reassessment of the control strategies, and particularly the prophylactic measures, that are necessary to keep the infection and spread of disease in check. Most of the available EHV-1 vaccines are based on preparations of inactivated virus, which are applied monovalently for prevention of EHV-1-caused abortion in pregnant mares or as part of multivalent vaccines to prevent...
Nam B, Mekuria Z, Carossino M, Li G, Zheng Y, Zhang J, Cook RF, Shuck KM, Campos JR, Squires EL, Troedsson MHT, Timoney PJ, Balasuriya UBR.Equine arteritis virus (EAV) is the causative agent of equine viral arteritis (EVA), a reproductive and respiratory disease of horses. Following natural infection, 10 to 70% of infected stallions can become carriers of EAV and continue to shed virus in the semen. In this study, sequential viruses isolated from nasal secretions, buffy coat cells, and semen of seven experimentally infected and two naturally infected EAV carrier stallions were deep sequenced to elucidate the intrahost microevolutionary process after a single transmission event. Analysis of variants from nasal secretions and buffy...
Müller I, Pinto E, Santibáñez MC, Celedón MO, Valenzuela PD.The equine influenza virus is the causal agent of influenza in horses. In July 2006, horses from various regions of Chile presented fever, serious nasal discharge, dry cough, anorexia and depression. Here we describe the isolation and characterization of the virus responsible for this outbreak. The virus was identified as equine influenza virus H3N8, since haemagglutination was inhibited by an anti-A/equi/1/H3N8 serum, but not by an anti-A/equi/1/H7N7 serum. The isolate was named A/equi/2/Lonquén/06 (H3N8). In addition, we describe the isolation and sequencing of the haemagglutinin, neuramini...
Tigre DM, Brandão CF, de Paula FL, Chinalia FA, Campos GS, Sardi SI.Equine infectious anemia is an important infectious disease that affects equids worldwide. Control of the disease is currently based on detection of anti-p26 EIAV by Agar Gel Immunodiffusion (AGID). In this work, 62 animals were examined by AGID and nested-PCR using primers for the gag gene. Fifty-three samples (85.5%) were positive by nested-PCR, whereas only 33 samples (53%) were positive for AGID. Fifteen amplicons obtained by nested-PCR were sequenced and the aligned results subjected to phylogenetic analysis. The analysis suggests that the Brazilian EIAV form a cluster with WSU5, EIAVUK a...
Mondal SP, Cook RF, Chelvarajan RL, Henney PJ, Timoney PJ, Balasuriya UB.Strains of equine arteritis virus (EAV) differ in their virulence phenotypes, causing anywhere from subclinical infections to severe disease in horses. Here, we describe the in silico design and de novo synthesis of a full-length infectious cDNA clone of the horse-adapted virulent Bucyrus strain (VBS) of EAV encoding mCherry along with in vitro characterization of the progeny virions (EAV sVBSmCherry) in terms of host-cell tropism, replicative capacity and stability of the mCherry coding sequences following sequential passage in cell culture. The relative stability of the mCherry sequence duri...
Lu G, Fu C, Huang J, Xu H, Wu P, Ping X, Li S.Equine pegivirus (EPgV) is a newly discovered equine virus, which is taxonomically classified in the Pegivirus genus of the Flaviviridae family. Until now, only the complete genome sequence of the first reported EPgV strain, from the USA (strain name: C0035) is available on online databases. Considering this, horse serum samples were collected from horses in China and screened for EPgV RNA by RT-PCR. One EPgV strain, LW/2016, was obtained and its near-complete genome sequence was acquired by standard PCR. Further analysis of its nucleotide sequence indicates LW/2016 is genetically divergent fr...
Read AJ, Arzey KE, Finlaison DS, Gu X, Davis RJ, Ritchie L, Kirkland PD.An outbreak of equine influenza (EI) occurred in Australia in 2007. During the laboratory support for this outbreak, real-time reverse transcriptase polymerase chain reaction (qRT-PCR) assays and a blocking enzyme linked immunosorbent assay (bELISA) were used as testing methods to detect infection with the virus. The qRT-PCR and bELISA tests had not been used for EI diagnosis before, so it was not known how soon after infection these tests would yield positive results, or for how long these results would remain positive. To answer these questions, nasal swabs and blood samples were collected d...
Porter MB, Long M, Gosche DG, Schott HM, Hines MT, Rossano M, Sellon DC.The West Nile (WN) virus, present in the United States since 1999, is a cause of encephalomyelitis in birds, alligators, humans, and horses. No data exist regarding detection of anti-WN virus immunoglobins in equine cerebrospinal fluid (CSF). The aims of this study were to evaluate the blood-brain barrier (BBB) in WN virus-infected (WNE) horses, to compare diagnostic testing in serum and CSF, and to describe the immunoglobulin M (IgM) response in serum and CSF of vaccinated horses. CSF was collected from the lumbosacral (LS) space (n = 13) or the allanto-occipital (AO) space (n = 14) of WNE ho...
Stoltz MA, van der Merwe CF, Coetzee J, Huismans H.The subcellular localization of the minor nonstructural protein NS3 of African horsesickness virus (AHSV) has been investigated by means of immunogold electron-microscopical analysis. NS3 was observed in perturbed regions of the plasma membrane of AHSV-infected VERO cells, and its presence appears to be associated with events of viral release. These events are budding, whereby released viruses acquire fragments from the host-cell membrane, as well as by the extrusion of nonenveloped particles through the cell membrane. The membrane association of NS3 was confirmed by its detection in the disru...
Nemoto M, Ryan E, Lyons P, Cullinane A.The molecular epidemiology of equine group A rotaviruses (RVAs) in Ireland from 2011 to 2015 was investigated. Of 438 diagnostic specimens submitted from foals with enteric disease, 102 (23.3%) were positive for RVA using an immunochromatographic assay. G genotypes were determined for 76 equine RVAs, of which 68 (89.5%) were G3 and eight (10.5%) were G14. Of 18 RVAs (12 G3 and six G14) characterised by P genotyping, all were P[12]. G3P[12] and G14P[12] were the most prevalent genotypes of RVA in foals in Ireland, similar to other countries and consistent with previous studies in Ireland from 1...
Cho HJ, Entz SC, Deregt D, Jordan LT, Timoney PJ, McCollum WH.A potent ELISA antigen was prepared from equine arteritis virus (EAV) by differential centrifugation of EAV-infected cell culture fluid, followed by solubilization of the preparation by Triton X-100 treatment. Using this antigen and a mouse monoclonal antibody against the G(L) protein of EAV, a reliable blocking ELISA (bELISA) was developed for the detection of EAV antibodies in equine sera. The bELISA was evaluated using a total of 837 test serum samples. The relative sensitivity (n = 320) of the bELISA compared to the serum neutralization (SN) test was 99.4%. The bELISA appears to be a highl...
