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.
Gao X, Jiang CG, Han XE, Zhao LP, Shen RX, Xiang WH, Zhou JH.To elucidate the function of the S2 gene in equine infectious anemia virus (EIAV) and its role in the attenuation of the Chinese attenuated EIAV vaccine strains, the S2 in the EIAV vaccine strain EIAV (FDDV) was reverse-mutated and the in vitro replication character of the resultant virus was evaluated. Based on the sequence variation of the S2 gene between the EIAV virulent strains and vaccine strains, all the four vaccine-specific sites in the S2 of an EIAV(FDDV) infectious clone, pFDDV3-8, were reverse-mutated to the sequences of the virulent strain EIAV(DV115). The reverse-mutated molecula...
Attoui H, Mendez-Lopez MR, Rao S, Hurtado-Alendes A, Lizaraso-Caparo F, Mohd Jaafar F, Samuel AR, Belhouchet M, Pritchard LI, Melville L, Weir RP....During 1997, two new viruses were isolated from outbreaks of disease that occurred in horses, donkeys, cattle and sheep in Peru. Genome characterization showed that the virus isolated from horses (with neurological disorders, 78% fatality) belongs to a new species the Peruvian horse sickness virus (PHSV), within the genus Orbivirus, family Reoviridae. This represents the first isolation of PHSV, which was subsequently also isolated during 1999, from diseased horses in the Northern Territory of Australia (Elsey virus, ELSV). Serological and molecular studies showed that PHSV and ELSV are very s...
Fortier G, van Erck E, Pronost S, Lekeux P, Thiry E.Equine gammaherpesviruses (γEHV) have been widely studied over the past 45 years and many isolates have been characterised. Despite this, the diagnosis of γEHV infection remains difficult to establish as its clinical manifestations lack specificity, ranging from mild respiratory signs in a small number of animals to outbreaks in large groups of young horses. This review focuses on the epidemiology, pathogenesis, clinical manifestations and diagnosis of equine herpesvirus (EHV)-2 and -5 infections, as well as on the genetic variation of these viruses. Study of these variations has resulted in...
Goehring LS, van Maanen C, Berendsen M, Cullinane A, de Groot RJ, Rottier PJ, Wesselingh JJ, Sloet van Oldruitenborgh-Oosterbaan MM.Equid herpesvirus type 1 (EHV-1)-associated myeloencephalopathy (EHM) may follow an infection with the virus in horses. This study tested three hypotheses: (1) a large inhaled dose of a neuropathogenic EHV-1 strain would induce a cell-associated viraemia in all infected horses; (2) neurological disease will only occur in viraemic horses, and (3) the cerebrospinal fluid (CSF) composition following EHV-1 viraemia will be an indicator for EHM. Four EHV-1 seronegative horses were inoculated with EHV-1 by inhalation. Three developed clinical signs of neurological disease, which were mild in two hor...
Hasebe R, Sasaki M, Sawa H, Wada R, Umemura T, Kimura T.We investigated the mechanism by which equine herpesvirus-1 (EHV-1) enters primary cultured equine brain microvascular endothelial cells (EBMECs) and equine dermis (E. Derm) cells. EHV-1 colocalized with caveolin in EBMECs and the infection was greatly reduced by the expression of a dominant negative form of equine caveolin-1 (ecavY14F), suggesting that EHV-1 enters EBMECs via caveolar endocytosis. EHV-1 entry into E. Derm cells was significantly reduced by ATP depletion and treatments with lysosomotropic agents. Enveloped virions were detected from E. Derm cells by infectious virus recovery a...
Smith KL, Allen GP, Branscum AJ, Frank Cook R, Vickers ML, Timoney PJ, Balasuriya UB.A panel of 426 archived EHV-1 isolates collected (1951-2006) from equine abortions was analyzed using a real-time Taq-Man((R)) allelic discrimination PCR assay. Based on previous findings, isolates possessing adenine at nucleotide position 2254 (A(2254)) in ORF30 were classified as having a non-neuropathogenic genotype and those with guanine at 2254 (G(2254)) were designated as the neuropathogenic genotype. The resultant data demonstrated that viruses with the neuropathogenic genotype existed in the 1950s and isolates with this genotype increased from 3.3% in the 1960s to 14.4% in the 1990s. T...
Frampton AR, Uchida H, von Einem J, Goins WF, Grandi P, Cohen JB, Osterrieder N, Glorioso JC.To initiate infection, equine herpesvirus type 1 (EHV-1) attaches to heparan sulfate on cell surfaces and then interacts with a putative glycoprotein D receptor(s). After attachment, virus entry occurs either by direct fusion of the virus envelope with the plasma membrane or via endocytosis followed by fusion between the virus envelope and an endosomal membrane. Upon fusion, de-enveloped virus particles are deposited into the cytoplasm and travel to the nucleus for viral replication. In this report, we examined the mechanism of EHV-1 intracellular trafficking and investigated the ability of EH...
Shirafuji H, Kanehira K, Kamio T, Kubo M, Shibahara T, Konishi M, Murakami K, Nakamura Y, Yamanaka T, Kondo T, Matsumura T, Muranaka M, Katayama Y.A group of horses immunized with inactivated Japanese encephalitis (JE) vaccine (JE-Immune Group) and a group of non-immunized horses (Non-Immune Group) were infected with West Nile virus (WNV). After WNV infection, neutralizing (Nt) antibody (Ab) titers to WNV were higher than those to JE virus (JEV) in the Non-Immune Group, but the NtAb titers to JEV were higher than those to WNV during most of the post-challenge observation period in the JE-Immune Group. Immunoglobulin M (IgM) Abs to WNV tested positive in the Non-Immune Group but negative in the JE-Immune Group, except for in one horse. Th...
Zoonoses and public healthJuly 30, 2009
Volume 57, Issue 7-8 476-486 doi: 10.1111/j.1863-2378.2009.01245.x
Monaco F, Lelli R, Teodori L, Pinoni C, Di Gennaro A, Polci A, Calistri P, Savini G.In August 2008, West Nile disease re-emerged in Italy. The infection is affecting the North Eastern regions and, as of November 2008, has caused 33 clinical cases and five fatalities in horses. Until now, no deaths have been reported in birds. Mosquitoes, blood, serum and tissue samples, from horses and birds, within and around the outbreak area, have been collected and tested by various methods both serologically and virologically. West Nile virus strains have been isolated from blood samples of one horse and one donkey and from pools of brain, kidneys, heart and spleen of a pigeon and three ...
Reperant LA, Rimmelzwaan GF, Kuiken T.Highly pathogenic avian influenza viruses of subtype H5N1 are remarkable because of their expanding non-avian host range and wide tissue tropism. They have caused severe or fatal respiratory and extra-respiratory disease in seven naturally infected species of carnivore. However, they are not unique in their ability to cross the species barrier, to cause clinical disease and mortality, or to replicate in extra-respiratory organs. Low pathogenic avian influenza viruses have crossed from birds to swine, horses, harbour seals, whales and mink; have resulted in severe respiratory disease and mortal...
Andoh K, Kai K, Matsumura T, Maeda K.Cell lines originating from horses are necessary for isolation and propagation of equine herpesviruses (EHV). Although we established an equine-derived cell line, FHK-Tcl3, propagation ceased after fewer than 40 passages. In this study, FHK-Tcl3 cell propagation continued beyond 40 passages, achieving over 100 passages. FHK-Tcl3 cells were then cloned by limiting dilution at the 100th passage. Cloned cells were termed FHK-Tcl3.1. FHK-Tcl3.1 cells grew well and were propagated every 3 to 4 days by splitting 1:5. In addition, EHV-1, -2 and -4 showed a clear cytopathic effect (CPE) in FHK-Tcl3.1 ...
Gobeil PA, Yuan Z, Gault EA, Morgan IM, Campo MS, Nasir L.Equine sarcoids are skin tumours of horses caused by infection with BPV-1 or 2. Maintenance and replication of the viral genome depend upon the viral proteins E1 and E2. We examined the effects of an E2 specific siRNA on E2 and E1 viral gene expression, viral load and cell growth in BPV-1 transformed sarcoid-derived cells. Transfection with E2-siRNA caused a reduction in E2 and E1 mRNA expression as well as viral load, growth inhibition and decreased anchorage-independent growth. siRNA treated cells showed significantly higher apoptosis rates than control cells. Thus sequence specific targetin...
Docherty DE, Samuel MD, Egstad KF, Griffin KM, Nolden CA, Karwal L, Ip HS.After the 2001 occurrence of West Nile virus (WNV) in Wisconsin (WI), we collected sera, during 2003-2006, from south-central WI mesopredators. We tested these sera to determine WNV antibody prevalence and geometric mean antibody titer (GMAT). Four-fold higher antibody prevalence and 2-fold higher GMAT in 2003-2004 indicated greater exposure of mesopredators to WNV during the apparent epizootic phase. The period 2005-2006 was likely the enzootic phase because WNV antibody prevalence fell to a level similar to other flaviviruses. Our results suggest that, in mesopredators, vector-borne transmis...
Yamanaka T, Nemoto M, Tsujimura K, Kondo T, Matsumura T.In horse populations, influenza A virus subtype H3N8 (equine influenza virus, EIV) is a very important pathogen that leads to acute respiratory disease. Recently, EIV has emerged in dogs, and has become widespread among the canine population in the United States. The interspecies transmission route had thus far remained unclear. Here, we tested whether the interspecies transmission of EIV to dogs could occur as a result of close contact with experimentally EIV-infected horses. Three pairs consisting of an EIV-infected horse and a healthy dog were kept together in individual stalls for 15 conse...
Vissani MA, Becerra ML, Olguín Perglione C, Tordoya MS, Miño S, Barrandeguy M.Infection with Equid Herpesvirus type 1 (EHV-1) leads to respiratory disease, abortion, and neurological disorders in horses. Molecular epidemiology studies have demonstrated that a single nucleotide polymorphism (A(2254)/G(2254)) in the genome region of the open reading frame 30 (ORF30), which results in an amino acid variation (N(752)/D(752)) of the EHV-1 DNA polymerase, is significantly associated with the neuropathogenic potential of naturally occurring strains. In order to estimate the prevalence of the EHV-1 neuropathogenic genotype in our country, we analyzed the ORF30 genome region of ...
Venter M, Human S, Zaayman D, Gerdes GH, Williams J, Steyl J, Leman PA, Paweska JT, Setzkorn H, Rous G, Murray S, Parker R, Donnellan C, Swanepoel R.Serologic evidence suggests that West Nile virus (WNV) is widely distributed in horses in southern Africa. However, because few neurologic cases have been reported, endemic lineage 2 strains were postulated to be nonpathogenic in horses. Recent evidence suggests that highly neuroinvasive lineage 2 strains exist in humans and mice. To determine whether neurologic cases are being missed in South Africa, we tested 80 serum or brain specimens from horses with unexplained fever (n = 48) and/or neurologic signs (n = 32) for WNV. From March 2007 through June 2008, using reverse transcription-PCR (RT-...
Guthrie AJ, Quan M, Lourens CW, Audonnet JC, Minke JM, Yao J, He L, Nordgren R, Gardner IA, Maclachlan NJ.We describe the development and preliminary characterization of a recombinant canarypox virus vectored (ALVAC) vaccine for protective immunization of equids against African horse sickness virus (AHSV) infection. Horses (n=8) immunized with either of two concentrations of recombinant canarypox virus vector (ALVAC-AHSV) co-expressing synthetic genes encoding the outer capsid proteins (VP2 and VP5) of AHSV serotype 4 (AHSV-4) developed variable titres (<10-80) of virus-specific neutralizing antibodies and were completely resistant to challenge infection with a virulent strain of AHSV-4. In contra...
Gregg K, Polejaeva I.Prevention and regulation of equine infectious anemia virus (EIAV) disease transmission solely depend on identification, isolation, and elimination of infected animals because of lack of an effective vaccine. Embryo production via the somatic cell nuclear transfer (SCNT) technology uses oocytes collected mainly from untested animals, which creates a potential risk of EIAV transmission through infected embryos. The current review examines the risk of EIAV disease transmission through SCNT embryo production and transfer. Equine infectious anemia virus is a lentivirus from the family Retroviridae...
Dzieciatkowski T, Chmielewska A, Turowska A, Tucholska A, Bańbura MW.In previous experiments, we have demonstrated that the presence of equine herpesvirus 2 (EHV-2) enhanced plaque formation in cell cultures infected with equine herpesvirus type 1. To determine whether a specific region of the EHV-2 genome is responsible for this effect, we have constructed a library of Bam HI fragments of the EHV-2 genome ligated into pcDNA plasmid. Equine dermal (ED) cell cultures were subsequently transfected with the constructs, passaged 5 times, tested for the presence of the plasmids and infected with EHV-1 at MOI = 0.01. Only in cultures transfected with the pcDNA/Bam HI...
Van de Walle GR, Goupil R, Wishon C, Damiani A, Perkins GA, Osterrieder N.Epidemiological studies have shown that a single-nucleotide polymorphism in the equid herpesvirus type 1 DNA polymerase gene is associated with outbreaks of highly lethal neurological disease in horses. Reverse genetics experiments further demonstrated that a G(2254) A(2254) nucleotide mutation introduced in neurovirulent strain Ab4, which resulted in an asparagine for aspartic acid substitution (D(752) N(752)), rendered the virus nonneurovirulent in the equine. Here, we report that the nonneurovirulent strain equid herpesvirus type 1 strain NY03 caused lethal neurological disease in horses af...
Zielonka J, Bravo IG, Marino D, Conrad E, Perković M, Battenberg M, Cichutek K, Münk C.The mammalian APOBEC3 (A3) proteins comprise a multigene family of cytidine deaminases that act as potent inhibitors of retroviruses and retrotransposons. The A3 locus on the chromosome 28 of the horse genome contains multiple A3 genes: two copies of A3Z1, five copies of A3Z2, and a single copy of A3Z3, indicating a complex evolution of multiple gene duplications. We have cloned and analyzed for expression the different equine A3 genes and examined as well the subcellular distribution of the corresponding proteins. Additionally, we have tested the functional antiretroviral activity of the equi...
Heerkens TM.Equine herpesvirus 1 (EHV-1) causes rhinopneumonitis, abortion, and rarely, myeloencephalopathy. The neurovirulence of this virus is due to a point mutation in the DNA polymerase gene. Diagnosis by virus isolation has been replaced by real-time polymerase chain reaction (RT-PCR) assays that can detect strains, viral loads, and states; this may aid in control and management of the disease. L’herpèsvirus équin de type-1 (EHV-1) cause la rhinopneumonie, l’avortement et rarement la myéloencéphalopathie. La neurovirulence de ce virus est attribuable à une mutation ponctuelle à l’intér...
Patel JR, Heldens JG.Since the refinement of tissue culture techniques for virus isolation and propagation from the mid 1960s onwards, veterinary virology has received much academic and industrial interest, and has now become a major global industry largely centred on vaccine development against economically important virus diseases of food animals. Bio-tech approaches have been widely used for improved vaccines development. While many viral diseases are controlled through vaccination, many still lack safe and efficacious vaccines. Additional challenges faced by academia, industry and governments are likely to com...
Fortier G, van Erck E, Fortier C, Richard E, Pottier D, Pronost S, Miszczak F, Thiry E, Lekeux P.The objectives of this study were to estimate the prevalence and the potential role of equine herpesviruses (EHVs) detection in both bronchoalveolar lavage (BAL) and tracheal wash (TW). The population included a control group (CTL; 37 TW and 25 BAL) and a pathological group (PAT; 259 TW and 387 BAL), including horses either suffering from respiratory diseases including syndrome of tracheal inflammation, inflammatory airway disease, recurrent airway obstruction, or submitted to respiratory investigation because of exercise intolerance or poor performance. Each respiratory liquid was submitted t...
Ma J, Jiang C, Lin Y, Wang X, Zhao L, Xiang W, Shao Y, Shen R, Kong X, Zhou J.To study the in vivo evolution of the attenuated Chinese equine infectious anemia virus (EIAV) vaccine, viral gp90 gene variation and virus replication in immunosuppressed hosts were investigated. The results showed that after vaccination, the gp90 gene followed an evolutionary trend of declining diversity. The trend coincided with the maturation of immunity to EIAV, and eventually, the gp90 gene became highly homologous. The sequences of these predominant quasispecies were consistently detected up to 18 months after vaccination. Furthermore, after transient immune suppression with dexamethaso...
Deardorff ER, Forrester NL, Travassos-da-Rosa AP, Estrada-Franco JG, Navarro-Lopez R, Tesh RB, Weaver SC.In 1993, an outbreak of encephalitis among 125 affected equids in coastal Chiapas, Mexico, resulted in a 50% case-fatality rate. The outbreak was attributed to Venezuelan equine encephalitis virus (VEEV) subtype IE, not previously associated with equine disease and death. To better understand the ecology of this VEEV strain in Chiapas, we experimentally infected 5 species of wild rodents and evaluated their competence as reservoir and amplifying hosts. Rodents from 1 species (Baiomys musculus) showed signs of disease and died by day 8 postinoculation. Rodents from the 4 other species (Liomys s...
Nemoto M, Tsujimura K, Yamanaka T, Kondo T, Matsumura T.Loop-mediated isothermal amplification (LAMP) is a novel method for the rapid and sensitive detection of DNA without the need for expensive equipment. In the present study, LAMP assays were developed for the specific detection of Equid herpesvirus 1 and 4 (EHV-1 and EHV-4, respectively) and for the differentiation of glycoprotein E (gE)-deleted EHV-1 (DeltagE) strain, a candidate strain for a live vaccine, from field EHV-1 strains. Specific primer sets were designed for the gC and gE genes of EHV-1 and for the gC gene of EHV-4. The analytical sensitivities of the LAMP assays were compared with...
Olsen CW, McGregor MW, Dybdahl-Sissoko N, Schram BR, Nelson KM, Lunn DP, Macklin MD, Swain WF, Hinshaw VS.Two fundamentally different approaches to vaccination of BALB/c mice with the hemagglutinin (HA) of A/Equine/Kentucky/1/81 (H3N8) (Eq/KY) were evaluated, that is, administration of HA protein vs administration of HA-encoding DNA. Each vaccine was tested for its immunogenicity and ability to provide protection from homologous virus challenge. HA protein was synthesized in vitro by infection of Sf21 insect cells with a recombinant baculovirus. Intranasal administration of this vaccine induced virus-specific antibodies, as measured by enzyme-linked immunosorbent assay (ELISA), but did not induce ...
Ranz AI, Miguet JG, Anaya C, Venteo A, Cortés E, Vela C, Sanz A.A panel of 32 hybridoma cell lines secreting monoclonal antibodies (MAbs) reactive with African horsesickness virus serotype 4 (AHSV-4) has been developed. Four of the MAbs recognized the major core antigen VP7, twenty recognized the outer capsid protein VP2 and eight reacted with the non-structural protein NS1. With the VP7-specific MAbs a rapid and sensitive double antibody sandwich immunoassay has been developed to detect viral antigen in infected Vero cells and in spleen tissue from AHSV-infected horses. The sensitivity of the assay is 10 ng viral antigen per 100 microliters. The NS1-speci...
Larson EM, Wagner B.Horses have many naturally occurring diseases that mimic similar conditions in humans. The ability to conduct environmentally controlled experiments and induced disease studies in a genetically diverse host makes the horse a valuable intermediate model between mouse studies and human clinical trials. This review highlights important similarities in the immune landscape between horses and humans using current research on two equine diseases as examples. First, equine herpesvirus type 1 (EHV-1) infection initiates a series of innate inflammatory signals at its mucosal entry site in the upper res...
Sun C, Zhang B, Jin J, Montelaro RC.The identification and characterization of a functional cellular receptor for equine infectious anemia virus (EIAV), designated equine lentivirus receptor-1 (ELR1), a member of the tumour necrosis factor receptor protein family, has been reported previously [Zhang, B. et al. (2005). Proc Natl Acad Sci U S A, 102 , 9918-9923]. The finding of a single receptor for EIAV is distinct from feline, simian and human immunodeficiency viruses, which typically utilize two co-receptors for infection, but is similar to avian and murine oncoviruses, which use single receptors. This study sought to determine...
Dam Van P, Desmecht D, Garigliany MM, Bui Tran Anh D, Van Laere AS.Type I/III interferons provide powerful and universal innate intracellular defense mechanisms against viruses. Among the antiviral effectors induced, Mx proteins of some species appear as key components of defense against influenza A viruses. It is expected that such an antiviral protein must display a platform dedicated to the recognition of said viruses. In an attempt to identify such platform in human MxA, an evolution-guided approach capitalizing on the antagonistic arms race between MxA and its viral targets and the genomic signature it left on primate genomes revealed that the surface-ex...
Mendes Junior AAV, Filgueira CPB, Miranda LFC, de Almeida AB, Cantanhêde LM, Fagundes A, Pereira SA, Menezes RC, Cupolillo E.Epidemiological data related to leishmaniases or Leishmania infection in horses are scarce. However, studies carried out in different regions in the world showed equids parasitised by Leishmania braziliensis, L. infantum and L. martiniquensis. Objective: Identify the Leishmania species causing cutaneous leishmaniasis in a mare, living in Rio de Janeiro State (Brazil), and search the presence of Leishmania viruses in the isolated parasite. Methods: Isoenzymes and polymerase chain reaction (PCR) targeting ITSrDNA region followed by sequencing were conducted for typing the isolated parasite. A se...
Dutta SK, Myrup AC, Thaker SR.Interference between equine herpesvirus types 1 (EHV-1) and 2 (EHV-2) was studied in equine dermis (ED) monolayer cell cultures and equine lymphocyte cultures. Cell cultures were infected with EHV-2, and after a short incubation period, the cultures were superinfected with EHV-1. At various intervals, different measurements of EHV-1 expression in dually infected cultures, compared with those in cultures infected with EHV-1 alone, were studied. In dually infected ED cell cultures, the EHV-1 cytopathic effect, EHV-1 titer, and EHV-1 enzyme-linked immunosorbent assay antigen titer were maximally ...
Altan E, Hui A, Li Y, Pesavento P, Asín J, Crossley B, Deng X, Uzal FA, Delwart E.Six foals with interstitial pneumonia of undetermined etiology from Southern California were analyzed by viral metagenomics. Spleen, lung, and colon content samples obtained during necropsy from each animal were pooled, and nucleic acids from virus-like particles enriched for deep sequencing. The recently described equine copiparvovirus named eqcopivirus, as well as three previously uncharacterized viruses, were identified. The complete ORFs genomes of two closely related protoparvoviruses, and of a bocaparvovirus, plus the partial genome of a picornavirus were assembled. The parvoviruses were...
Evans KS, Carpenter SL, Sevoian M.The enzyme-linked immunosorbent assay (ELISA) antigen-positive and agar-gel immunodiffusion test (AGID)-negative horses do not have infective equine infectious anemia (EIA) virus. The ELISA testing of horse leukocyte culture (HLC) supernatants did detect EIA virus in a HLC that was infected with the Wyoming strain of EIA virus and in HLC derived from horses in febrile, acute, or subacute stages of EIA infection. In supernatants of HLC derived from chronic and inapparent carrier horses, EIA virus was not detected with ELISA. Direct fluorescent antibody tests detected EIA virus in HLC infected w...
Rossi SL, Russell-Lodrigue KE, Plante KS, Bergren NA, Gorchakov R, Roy CJ, Weaver SC.Venezuelan equine encephalitis virus (VEEV) is a re-emerging virus of human, agriculture, and bioweapon threat importance. No FDA-approved treatment is available to combat Venezuelan equine encephalitis in humans, prompting the need to create a vaccine that is safe, efficacious, and cannot be replicated in the mosquito vector. Here we describe the use of a serotype ID VEEV (ZPC-738) vaccine with an internal ribosome entry site (IRES) to alter gene expression patterns. This ZPC/IRES vaccine was genetically engineered in two ways based on the position of the IRES insertion to create a vaccine th...
Proft A, Spiesschaert B, Izume S, Taferner S, Lehmann MJ, Azab W.The serine-threonine protein kinase encoded by gene (pUS3) of alphaherpesviruses was shown to modulate actin reorganization, cell-to-cell spread, and virus egress in a number of virus species. However, the role of the US3 orthologues of equine herpesvirus type 1 and 4 (EHV-1 and EHV-4) has not yet been studied. Here, we show that is not essential for virus replication in vitro. However, growth rates and plaque diameters of a -deleted EHV-1 and a mutant in which the catalytic active site was destroyed were significantly reduced when compared with parental and revertant viruses or a virus in w...
Ushimi C, Henson JB, Gorham JR.Primary horse leukocyte cultures were inoculated with 2 or 10 50% tissue culture infective doses (TCID(50)) of equine infectious anemia (EIA) virus per cell, and the titer of cell-associated and fluid-phase virus was determined from 1 to 72 hr postinoculation (PI). Cover slips were collected from 4 to 72 hr PI and stained for EIA viral antigen by the indirect immunofluorescent (FA) technique. Viral replication was detected after a latent period of approximately 18 to 24 hr and reached peak titers of approximately 10(4.5) to 10(6) TCID(50)/0.5 ml from 48 to 72 hr PI. The fluid phase contained 1...
Burgueño A, Spinsanti L, Díaz LA, Rivarola ME, Arbiza J, Contigiani M, Delfraro A.St. Louis encephalitis virus (SLEV) and West Nile virus (WNV) belong to the Japanese encephalitis antigenic complex (Flavivirus genus, Flaviviridae family). They show antigenic close relationships and share many similarities in their ecology. Both are responsible for serious human diseases. The aim of this study was to investigate the presence of neutralizing antibodies to these viruses in horses from Uruguay. To do this, 425 horse sera were collected in 2007 and analyzed by plaque reduction neutralization tests. As a result, 205 sera (48.2%) were found positive for SLEV, with titers ranging b...
Chung C, Mealey RH, McGuire TC.Cytotoxic T lymphocytes (CTL) are critical for lentivirus control including EIAV. Since CTL from most EIAV carrier horses recognize Gag epitope clusters (EC), the hypothesis that carrier horses would have high functional avidity CTL to optimal epitopes in Gag EC was tested. Twenty-two optimal EC epitopes were identified; two in EC1, six in EC2, and seven each in EC3 and 4. However, only five of nine horses had high functional avidity CTL (<or=11 nM) recognizing six epitopes in EC; four in relatively conserved EC3; and one each in EC1 and 2. Horses with high functional avidity CTL had signif...
Reubel GH, Crabb BS, Studdert MJ.Nested polymerase chain reaction (PCR) assays were developed for the detection of equine herpesvirus 2 (EHV2) and equine herpesvirus 5 (EHV5) using the nucleotide sequences from the glycoprotein B (gB) gene of EHV2 and the thymidine kinase (TK) gene of EHV5. The simultaneous use of EHV2 specific and EHV5 specific primers in one nested amplification assay (multiplex PCR) enabled a rapid, specific and sensitive diagnosis for each virus. PCR was found to be 10(3) times more sensitive than virus isolation by cell culture for EHV2 and 10(6) for EHV5. In separate PCR assays, the routine detection li...
Dietz WH, Alvarez O, Martin DH, Walton TE, Ackerman LJ, Johnson KM.Forty-five horses were infected peripherally or intrathecally with enzootic or epizootic strains of Venezuelan equine encephalomyelitis (VEE) virus. Low titers of virus appeared in cerebrospinal fluid (CSF) after peripheral inoculation of enzootic or epizootic VEE virus strains. Intrathecal infection with either epizootic or enzootic VEE virus produced higher titers of virus in CSF than did peripheral infection. In contrast to peripheral infections with enzootic strains, intrathecal infections with these strains caused death. The animals that died had widespread histopathologic changes and lar...
Sarkar S, Balasuriya UB, Horohov DW, Chambers TM.Equine herpesvirus-1 (EHV-1) is a major respiratory viral pathogen of horses, causing upper respiratory tract disease, abortion, neonatal death, and neurological disease that may lead to paralysis and death. EHV-1 replicates initially in the respiratory epithelium and then spreads systemically to endothelial cells lining the small blood vessels in the uterus and spinal cord leading to abortion and EHM in horses. Like other herpesviruses, EHV-1 employs a variety of mechanisms for immune evasion including suppression of type-I interferon (IFN) production in equine endothelial cells (EECs). Previ...
Tang Z, Li X, Wang X, Zhang C, Zou L, Ren H, Liu W. () is one of the foremost pathogens responsible for diarrhea in foals. As antibiotic resistance increases, phages that specifically lyse bacteria are of great interest to us with regard to . In this study, a novel phage DCp1 was isolated from the sewage of a donkey farm. Phage DCp1 had a non-contractile short tail (40 nm in length) and a regular icosahedral head (46 nm in diameter). Whole-genome sequencing indicated that phage DCp1 had a linear double-stranded DNA genome with a total length of 18,555 bp and a G + C content of 28.2%. A total of 25 ORFs were identified in the genome, 6 of whic...
Melnick JL, Hampil B.This paper smmarizes the results of the third part of co-operative studies undertaken by the WHO International Reference Centre for Enteroviruses and a number of WHO Regional Virus Reference Centres and WHO Virus Collaborating Laboratories and other laboratories in a comprehensive testing programme of enterovirus equine antisera prepared for long-term use as reference antisera. The studies were designed to appraise the specificity of the immune serum of horses inoculated with prototype enteroviruses (coxsackie-viruses A1, A5, A6, A12 and A22 and echoviruses 5, 6, 13-16, 18-20, 22-26, 29 and 32...
Newman MJ, Issel CJ, Truax RE, Powell MD, Horohov DW, Montelaro RC.Suppression of the immune system is a common aspect of the disease pathogenesis associated with retroviral infections in both man and animals. We have measured transient suppression of the equine immune system as a loss or decrease in antigen-specific and polyclonal lymphocyte proliferation following experimental infection of ponies with three variants of equine infectious anemia virus (EIAV) with difference virulence characteristics. The transient suppression of proliferative responses was temporally associated with recurrent febrile episodes, which are the hallmark symptom of EIAV-induced di...
Pusterla N, Magdesian KG, Mapes SM, Zavodovskaya R, Kass PH.The ante mortem diagnosis of equine multinodular pulmonary fibrosis (EMPF) relies on histopathological results and polymerase chain reaction (PCR)-positive equine herpesvirus (EHV)-5 testing of lung tissue. Polymerase chain reaction detection of EHV-5 in bronchoalveolar lavage fluid (BALF) is commonly used to support a diagnosis of EMPF. However, the diagnostic power of EHV-5 testing on BALF and other biological samples such as blood and nasal secretions has yet to be shown to support a diagnosis of EMPF. Objective: To determine the frequency of detection and the viral loads of EHV-5 by quanti...
Plummer G, Bowling CP, Goodheart CR.Four equine herpesviruses (equine abortion virus, equine herpesvirus types 2 and 3, and equine cytomegalovirus) were compared. The equine abortion virus did not cross-neutralize with any of the other viruses, but the other three did show varying degrees of cross-neutralization among themselves. Equine abortion virus grew more quickly in tissue cultures than did the others, and attained higher titers of infectivity in the culture fluid; it also formed plaques in a wider range of tissue culture species, although the other three were not specific for one tissue culture system only, in that they w...
Potgieter AC, Cloete M, Pretorius PJ, van Dijk AA.The outer capsid protein VP2 of African horsesickness virus (AHSV) is a major protective antigen. We have cloned full-length VP2 genes from the reference strains of each of the nine AHSV serotypes. Baculovirus recombinants expressing the cloned VP2 genes of serotypes 1, 2, 4, 6, 7 and 8 were constructed, confirming that they all have full open reading frames. This work completes the cloning and expression of the first full set of AHSV VP2 genes. The clones of VP2 genes of serotypes 1, 2, 5, 7 and 8 were sequenced and their amino acid sequences were deduced. Our sequencing data, together with t...
Date T, Sugiyama M, Lkhagvasuren D, Wakita T, Oyunsuren T, Mizokami M.Equine hepacivirus (EHV) belongs to the hepacivirus A and is related to hepatitis C virus (HCV). This virus shows hepatic tropism and is known to chronically infect horses. EHV has been reported from various countries, but the prevalence in Mongolia, where large horse populations are pastured, remains unknown. This study collected serum samples from horses in six areas across Mongolia, in order to investigate the status of infection. The possibility of human infection was also examined. The results showed an infection rate among horses of about 40 % in all regions. However, no evidence of EHV ...
Scherer WF, Cupp EW, Lok JB, Brenner RJ, Ordonez JV.The minimal intestinal dose of an enzootic strain of Venezuelan encephalitis (VE) virus for Culex (Melanoconion) taeniopus mosquitoes caught at a marsh habitat of VE virus in Guatemala was less than five plaque forming units (pfu) of virus. Ingestion of this dose of virus in blood of viremic hamsters resulted in transmission of virus to other hamsters. This low intestinal threshold of an enzootic strain of VE virus indicates that the natural Guatemalan population of Cu. (Mel.) taeniopus can acquire VE virus from vertebrates that have viremia levels as low as 1,000-5,000 pfu/ml of blood, provid...
Verwoerd DW.In the early colonial history of South Africa, horses played an important role, both in general transportation and in military operations. Frequent epidemics of African horsesickness (AHS) in the 18th century therefore severely affected the economy. The first scientific research on the disease was carried out by Alexander Edington (1892), the first government bacteriologist of the Cape Colony, who resolved the existing confusion that reigned and established its identity as a separate disease. Bluetongue (BT) was described for the first time by Duncan Hutcheon in 1880, although it was probably ...
Olguin-Perglione C, Barrandeguy ME.Equine influenza virus (EIV) is one of the most important respiratory pathogens of horses as outbreaks of the disease lead to significant economic losses worldwide. In this review, we summarize the information available on equine influenza (EI) in South America. In the region, the major events of EI occurred almost in the same period in the different countries, and the EIV isolated showed high genetic identity at the hemagglutinin gene level. It is highly likely that the continuous movement of horses, some of them subclinically infected, among South American countries, facilitated the spread o...
Abdel-Moneim AS, Shehab GM, Abu-Elsaad AA.Phylogenetic and evolutionary patterns of the six internal genes of an equine H5N1 influenza A virus isolated in Egypt on 2009 were analyzed using direct sequencing. All of the internal genes of the equine H5N1 strain showed a genetic pattern potentially related to Eurasian lineages. Variable dendrogram topologies revealed an absence of reassortment in the equine strain while confirming its close relatedness to other Egyptian H5N1 strains from human and avian species. The equine strain is characterized by a variety of amino acid substitutions in six internal proteins compared to the available ...
Compton JR, Mickey MJ, Hu X, Marugan JJ, Legler PM.The alphaviral nsP2 cysteine protease of the Venezuelan equine encephalitis virus (VEEV) is a validated antiviral drug target. Clan CN proteases contain a cysteine protease domain that is intimately packed with an S-adenosyl-l-methionine-dependent RNA methyltransferase (SAM MTase) domain. Within a cleft formed at the interface of these two domains, the peptide substrate is thought to bind. The nucleophilic cysteine can be found within a conserved motif, NVCWAK, which differs from that of papain (CGSCWAFS). Mutation of the motif residue, N475, to alanine unexpectedly produced a self-inhibited s...
