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Topic:Virus
The study of viral infections that affect equine species assesses the relationship between viruses and horses. Infections can lead to a range of clinical symptoms and may impact the health and performance of horses. Common equine viruses include Equine Influenza Virus, Equine Herpesvirus, and West Nile Virus, among others. Understanding the mechanisms of viral transmission, pathogenesis, and host immune responses is essential for developing effective prevention and treatment strategies. This page compiles peer-reviewed research studies and scholarly articles that explore the epidemiology, molecular biology, and clinical management of viral infections in horses.
Isolation and partial sequencing of Equid herpesvirus 5 from a horse in Iceland. Horses are hosts to 2 types of gammaherpesviruses, Equid herpesvirus 2 and 5 (EHV-2 and EHV-5, respectively). Both EHV-2 and EHV-5 are common in horses in Iceland. An Icelandic EHV-5 isolate was recovered by sequential culture in primary fetal horse kidney and rabbit kidney cells. Glycoprotein B, glycoprotein H, and DNA terminase genes of the isolate were fully sequenced, and the DNA polymerase gene was partly sequenced. To date, the glycoprotein B gene of EHV-5 was the only gene that has been reported to be completely sequenced in addition to small parts of the glycoprotein H, DNA polymerase,...
Intra- and interhost evolutionary dynamics of equine influenza virus. Determining the evolutionary basis of cross-species transmission and immune evasion is key to understanding the mechanisms that control the emergence of either new viruses or novel antigenic variants with pandemic potential. The hemagglutinin glycoprotein of influenza A viruses is a critical host range determinant and a major target of neutralizing antibodies. Equine influenza virus (EIV) is a significant pathogen of the horse that causes periodical outbreaks of disease even in populations with high vaccination coverage. EIV has also jumped the species barrier and emerged as a novel respirator...
Molecular epidemiology and genetic characterization of equine arteritis virus isolates associated with the 2006-2007 multi-state disease occurrence in the USA. In 2006-2007, equine viral arteritis (EVA) was confirmed for the first time in Quarter Horses in multiple states in the USA. The entire genome of an equine arteritis virus (EAV) isolate from the index premises in New Mexico was 12 731 nt in length and possessed a previously unrecorded unique 15 nt insertion in the nsp2-coding region in ORF1a and a 12 nt insertion in ORF3. Sequence analysis of additional isolates made during this disease occurrence revealed that all isolates from New Mexico, Utah, Kansas, Oklahoma and Idaho had 98.6-100.0 % (nsp2) and 97.8-100 % (ORF3) nucleotide identity and c...
Identification of cellular proteins interacting with equine infectious anemia virus S2 protein. 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...
West Nile virus circulation in Emilia-Romagna, Italy: the integrated surveillance system 2009. Following a large West Nile virus (WNV) epidemic in northeastern Italy in 2008, human and animal surveillance activities were implemented in Emilia Romagna. Human surveillance was performed by serology or genome detection on blood and cerebrospinal fluid for all suspected cases suffering from acute meningoencephalitis in the regional territory. Animal surveillance consisted of passive and active surveillance of horses and active surveillance of wild birds and mosquitoes. Between 15 June and 31 October 2009, nine of 78 possible cases of West Nile neuroinvasive disease were confirmed (three fata...
Selection of a rare neutralization-resistant variant following passive transfer of convalescent immune plasma in equine infectious anemia virus-challenged SCID horses. Vaccines preventing HIV-1 infection will likely elicit antibodies that neutralize diverse strains. However, the capacity for lentiviruses to escape broadly neutralizing antibodies (NAbs) is not completely understood, nor is it known whether NAbs alone can control heterologous infection. Here, we determined that convalescent immune plasma from a horse persistently infected with equine infectious anemia virus (EIAV) neutralized homologous virus and several envelope variants containing heterologous principal neutralizing domains (PND). Plasma was infused into young horses (foals) affected with se...
Development and usage of eXtension’s HorseQuest: an online resource. eXtension (pronounced e-extension) is an online resource transforming how faculty can collaborate and deliver equine education. As the first Community of Practice launched from eXtension, HorseQuest (HQ) offers free, interactive, peer-reviewed, online resources on a variety of equine-related topics at http://www.extension.org. This group has adapted traditional educational content to the online environment to maximize search engine optimization, to be more discoverable and relevant in the online world. This means that HQ resources are consistently being found on the first page of search result...
Cell entry of the aphthovirus equine rhinitis A virus is dependent on endosome acidification. Equine rhinitis A virus (ERAV) is genetically closely related to foot-and-mouth disease virus (FMDV), and both are now classified within the genus Aphthovirus of the family Picornaviridae. For disease security reasons, FMDV can be handled only in high-containment facilities, but these constraints do not apply to ERAV, making it an attractive alternative for the study of aphthovirus biology. Here, we show, using immunofluorescence, pharmacological agents, and dominant negative inhibitors, that ERAV entry occurs (as for FMDV) via clathrin-mediated endocytosis and acidification of early endosomes...
[African horse sickness and equine encephalosis: must Switzerland get prepared]. African horse sickness (AHS) of equines is partly transmitted by the same culicoides species as Bluetongue (BT) disease in even-toed ungulates. Horses normally get seriously sick, with a high case fatality rate. Equine Encephalosis is another, but less-known viral disease of equines, caused by viruses of the same genus as BT and AHS. Like BT of serotype 8 in 2006, both diseases could theoretically be introduced to Europe anytime and spread rapidly then. After the lessons learnt from the most recent bluetongue outbreaks in Europe, the regulations and AHS-contingency plans in force must be updat...
Influenza virus transmission from horses to dogs, Australia. During the 2007 equine influenza outbreak in Australia, respiratory disease in dogs in close contact with infected horses was noted; influenza (H3N8) virus infection was confirmed. Nucleotide sequence of the virus from dogs was identical to that from horses. No evidence of dog-to-dog transmission or virus persistence in dogs was found.
Immunochromatographic lateral flow test for detection of antibodies to Equine infectious anemia virus. The purpose of this study was to develop and evaluate a simple immunochromatographic lateral flow (ICLF) test for specific detection of Equine infectious anemia virus (EIAV) antibodies in equine sera. Viral recombinant p26 capsid protein (rp26) was used as the capture protein in the test line and as the detector reagent conjugated to colloidal gold. The performance of rp26-ICLF was evaluated, and the results obtained were compared with a commercially available agar gel immunodiffusion (AGID) test used as a standard of comparison according to international guidelines. The values obtained for co...
Opposite effects of two different strains of equine herpesvirus 1 infection on cytoskeleton composition in equine dermal ED and African green monkey kidney Vero cell lines: application of scanning cytometry and confocal-microscopy-based image analysis in a quantitative study. Viruses can reorganize the cytoskeleton and restructure the host cell transport machinery. During infection viruses use different cellular cues and signals to enlist the cytoskeleton for their mission. However, each virus specifically affects the cytoskeleton structure. Thus, the aim of our study was to investigate the cytoskeletal changes in homologous equine dermal (ED) and heterologous Vero cell lines infected with either equine herpesvirus 1 (EHV-1) strain Rac-H or Jan-E. We found that Rac-H strain disrupted actin fibers and reduced F-actin level in ED cells, whereas the virus did not infl...
Efficacy of a whole inactivated EI vaccine against a recent EIV outbreak isolate and comparative detection of virus shedding. An outbreak of H3N8 Equine Influenza virus (EIV) that occurred in vaccinated horses in Japan was caused by a genetically divergent EIV isolate of the Florida clade 1 sub-lineage. This virus subsequently entered Australia where it infected thousands of immunologically naïve horses. The objective of this study was to evaluate the ability of a non-updated whole inactivated equine influenza (EI) vaccine to protect if used in the face of an outbreak induced by a virus similar to the ones circulating in Japan and Australia in 2007. Seven naïve Welsh mountain ponies were immunised twice with the co...
Development and optimisation of a duplex real-time reverse transcription quantitative PCR assay targeting the VP7 and NS2 genes of African horse sickness virus. Nucleotide sequences of 52 South African isolates of African horse sickness virus (AHSV) collected during 2004-2005 and including viruses of all nine AHSV serotypes, were used to design and develop a duplex real-time reverse transcription quantitative PCR (RT-PCR) assay targeting the VP7 (S8) and NS2 (S9) genes of AHSV. The assay was optimized for detection of AHSV in fresh and frozen blood of naturally infected horses. Assay performance was enhanced using random hexamers rather than gene-specific primers for RT, and with denaturation of double-stranded RNA in the presence of random hexamers. ...
Glycoprotein C of equine herpesvirus 4 plays a role in viral binding to cell surface heparan sulfate. Heparan sulfate moieties of cell surface proteoglycans serve as receptors for several herpesviruses. For herpes simplex virus 1, pseudorabies virus and equine herpesvirus 1, glycoprotein C (gC) homologues have been shown to mediate the binding to cell surface heparan sulfate. However, the role of gC in equine herpesvirus 4 (EHV-4) infection has not yet been analyzed. Using pull-down assay, we first determined that EHV-4 gC as well as gB are heparin-binding glycoproteins. To study the role of gC in EHV-4 infection, we constructed a gC-deletion mutant, WA79DeltagC, where the kanamycin resistant ...
[Receptors for animal retroviruses]. Diseases caused by animal retroviruses have been recognized since 19th century in veterinary field. Most livestock and companion animals have own retroviruses. To disclose the receptors for these retroviruses will be useful for understanding retroviral pathogenesis, developments of anti-retroviral drugs and vectors for human and animal gene therapies. Of retroviruses in veterinary field, receptors for the following viruses have been identified; equine infectious anemia virus, feline immunodeficiency virus, feline leukemia virus subgroups A, B, C, and T, Jaagsiekte sheep retrovirus, enzootic na...
Complex interactions between the major and minor envelope proteins of equine arteritis virus determine its tropism for equine CD3+ T lymphocytes and CD14+ monocytes. Extensive cell culture passage of the virulent Bucyrus (VB) strain of equine arteritis virus (EAV) to produce the modified live virus (MLV) vaccine strain has altered its tropism for equine CD3(+) T lymphocytes and CD14(+) monocytes. The VB strain primarily infects CD14(+) monocytes and a small subpopulation of CD3(+) T lymphocytes (predominantly CD4(+) T lymphocytes), as determined by dual-color flow cytometry. In contrast, the MLV vaccine strain has a significantly reduced ability to infect CD14(+) monocytes and has lost its capability to infect CD3(+) T lymphocytes. Using a panel of five re...
Molecular and biological characterization of equine infectious anemia virus Rev. Equine infectious anemia virus (EIAV) is one of the most divergent members of the lentivirus subfamily of retroviruses and is considered a useful comparative model for molecular studies of lentivirus replication. The Rev protein of EIAV is functionally homologous with other lentiviral Revs and facilitates export of incompletely spliced viral mRNAs through a Crm1-dependent pathway. The trans- and cis-acting elements that mediate EIAV Rev function are similar to, but distinct from, the well-characterized elements in human immunodeficiency virus (HIV-1), the prototypical Rev protein. In addition,...
Virulence determinants of equine infectious anemia virus. Equine infectious anemia virus (EIAV) is a macrophage-tropic lentivirus that rapidly Induces disease in experimentally infected horses. Because EIAV infection and replication is centered on the monocyte/macrophage and has a pronounced acute disease stage, it is a useful model system for understanding the contribution of monocyte/macrophages to other lentivirus-induced diseases. Genetic mapping studies utilizing chimeric proviruses in which parental viruses are acutely virulent or avirulent have allowed the identification of important regions that influence acute virulence. U3 regions in the vi...
Curing of HeLa cells persistently infected with equine arteritis virus by a peptide-conjugated morpholino oligomer. A significant consequence of equine arteritis virus (EAV) infection of horses is persistence of the virus in a variable percentage of infected stallions. We recently established an in vitro model of EAV persistence in cell culture for the purpose of furthering our understanding of EAV biology in general and viral persistence in the stallion in particular. In this study we investigated whether persistently infected HeLa cells could be cured of EAV infection by treatment with an antisense peptide-conjugated phosphorodiamidate morpholino oligomer (PPMO) designed to target the 5'-terminal region o...
Residue 752 in DNA polymerase of equine herpesvirus type 1 is non-essential for virus growth in vitro. A single amino acid variation in the equine herpesvirus type 1 (EHV-1) DNA polymerase (Pol) (D752/N752) determines its neuropathogenic potential. Here, an EHV-1 strain RacL11 mutant with a deletion of Pol residue 752 was constructed. The deletion virus was then repaired to encode D752 or N752, respectively. The Delta752 mutant virus replicated with kinetics indistinguishable from those of D752 and N752 viruses. In addition, we could demonstrate that the deletion mutant was significantly more resistant to aphidicolin, a drug targeting Pol, compared with the N752 but not the D752 variant. In equ...
Animal models of CNS viral disease: examples from borna disease virus models. Borna disease (BD), caused by the neurotropic RNA virus, Borna Disease virus, is an affliction ranging from asymptomatic to fatal meningoencephalitis across naturally and experimentally infected warmblooded (mammalian and bird) species. More than 100 years after the first clinical descriptions of Borna disease in horses and studies beginning in the 1980's linking Borna disease virus to human neuropsychiatric diseases, experimentally infected rodents have been used as models for examining behavioral, neuropharmacological, and neurochemical responses to viral challenge at different stages of lif...
Real-time RT-PCR for the detection and quantitative analysis of equine rhinitis viruses. Equine rhinitis viruses (ERV) cause respiratory disease and loss of performance in horses. It has been suggested that the economic significance of these viruses may have been underestimated due to insensitive methods of detection. Objective: To develop a sensitive, rapid, real-time RT-PCR (rRT-PCR) assay suitable for the routine diagnosis and epidemiological surveillance of the A and B variants of ERV. Methods: TaqMan primer probe sets for ERAV and ERBV were designed from conserved regions of the 5' UTR of the ERV genome. Over 400 samples from both clinically affected and asymptomatic horses w...
Dynamics of influenza virus infection and pathology. A key question in pandemic influenza is the relative roles of innate immunity and target cell depletion in limiting primary infection and modulating pathology. Here, we model these interactions using detailed data from equine influenza virus infection, combining viral and immune (type I interferon) kinetics with estimates of cell depletion. The resulting dynamics indicate a powerful role for innate immunity in controlling the rapid peak in virus shedding. As a corollary, cells are much less depleted than suggested by a model of human influenza based only on virus-shedding data. We then explore...
An inactivated Vero cell-grown Japanese encephalitis vaccine formulated with Advax, a novel inulin-based adjuvant, induces protective neutralizing antibody against homologous and heterologous flaviviruses. Advax is a polysaccharide-based adjuvant that potently stimulates vaccine immunogenicity without the increased reactogenicity seen with other adjuvants. This study investigated the immunogenicity of a novel Advax-adjuvanted Vero cell culture candidate vaccine against Japanese encephalitis virus (JEV) in mice and horses. The results showed that, in mice, a two-immunization, low-dose (50 ng JEV antigen) regimen with adjuvanted vaccine produced solid neutralizing immunity comparable to that elicited with live ChimeriVax-JE immunization and superior to that elicited with tenfold higher doses of a ...
Isolation and genetic characterization of H3N8 equine influenza virus from donkeys in China. During the 2007 outbreak of equine influenza (EIV) in China, an influenza virus designated A/donkey/Xinjiang/5/2007 (donkey/Xinjiang/2007) was isolated from a symptomatic donkey in Xinjiang Uygur Autonomous Region, China. To analyze the genetic evolution of the new isolate, the hemagglutinin (HA) gene of donkey/Xinjiang/2007 was amplified and sequenced. Sequence alignment, prediction of glycosylation sites and phylogenetic analysis of the HA1 protein of donkey/Xinjiang/2007 showed most similarity to the Florida sublineage clade 2 of the American lineage of equine influenza viruses. The HA1 seq...
Re-emergence of bluetongue, African horse sickness, and other orbivirus diseases. Arthropod-transmitted viruses (Arboviruses) are important causes of disease in humans and animals, and it is proposed that climate change will increase the distribution and severity of arboviral diseases. Orbiviruses are the cause of important and apparently emerging arboviral diseases of livestock, including bluetongue virus (BTV), African horse sickness virus (AHSV), equine encephalosis virus (EEV), and epizootic hemorrhagic disease virus (EHDV) that are all transmitted by haematophagous Culicoides insects. Recent changes in the global distribution and nature of BTV infection have been espec...
Loop-mediated isothermal amplification assays for detection of Equid herpesvirus 1 and 4 and differentiating a gene-deleted candidate vaccine strain from wild-type Equid herpesvirus 1 strains. 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...
