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.
Ghanem YM, Ibrahim el-SM, Yamada S, Matsumura T, Osterrieder N, Yamaguchi T, Fukushi H.The pathogenicities of RacL11 and Kentucky D strains of equine herpesvirus 1 in the hamster infection model are different from those of Ab4p and the Japanese isolates. Virus genome restriction fragment length polymorphism analysis and sequence comparison of an intergenic region, glycoproteins and tegument genes showed higher conservation but with some strain-specific differences. These results indicate that point nucleotide differences in RacL11 and Kentucky D might be responsible for their pathogenicity in rodent models.
Zerpa H, Berhane Y, Elliott J, Bailey SR.The vasculature of the equine digit fulfils an important role in thermoregulation. In other species, it has been found that cooling may enhance the response of cutaneous vessels to 5-hydroxytryptamine (5-HT) and alpha(2)-adrenoceptor agonists. Translocation of alpha(2)-adrenoceptors to the smooth muscle cell membrane, mediated by Rho kinase, is thought to be involved in the cooling-enhanced response in mouse tail arteries. However, little is known about the effect of cooling on 5-HT receptor function. The present investigation compared the response of 5-bromo-6-(2-imidazolin-2-ylamino) quinoxa...
Zhou T, Yuan XF, Hou SH, Tu YB, Peng JM, Wen JX, Qiu HJ, Wu DL, Chen HC, Wang XJ, Tong GZ.In the early 1970s, the Chinese Equine Infectious Anemia Virus (EIAV) vaccine, EIAV(DLA), was developed through successive passages of a wild-type virulent virus (EIAV(L)) in donkeys in vivo and then in donkey macrophages in vitro. EIAV attenuation and cell tropism adaptation are associated with changes in both envelope and long terminal repeat (LTR). However, specific LTR changes during Chinese EIAV attenuation have not been demonstrated. In this study, we compared LTR sequences from both virulent and attenuated EIAV strains and documented the diversities of LTR sequence from in vivo and in v...
Quinlivan M, Cook RF, Cullinane A.In 2006, an outbreak of equine infectious anaemia (EIA) occurred in Ireland. The initial source of the outbreak is believed to have been contaminated plasma imported from Italy. This paper presents the nucleotide sequence of the gag gene of the virus identified in Ireland (EIAV(Ire)), the first for a European strain of EIAV. Comparison of the gag gene with North American and Asian strains of the virus showed that the gag gene is less well conserved than previously believed, and that EIAV strains can have similar phenotypes despite considerable variations in genotype. On the basis of the deduce...
Kang J, Lee MS, Watowich SJ, Gorenstein DG.A phosphorothioate RNA aptamer (thioaptamer) targeting the capsid protein of Venezuelan equine encephalitis virus (VEEV) was isolated by in vitro combinatorial selection. The selected thioaptamer had a strong binding affinity (approximately 7nM) and high specificity for the target protein. For the binding to the protein, the overall tertiary structure of the thioaptamer is required. We introduce two theoretical methods to examine the effect of phosphorothioate modification on the enhancement of binding affinity and one experimental method to examine the nature of the multiple bands of thioapta...
Bowen RA, Nemeth NM.West Nile virus emerged recently in North America as a serious human and animal pathogen. This review summarizes the use of experimental infections with West Nile virus in diverse vertebrate species that have been used to answer fundamental questions about the host response, pathogenesis of West Nile virus infection and virus evolution. Results: West Nile virus has an extremely broad vertebrate host range. Infection of common species of birds has defined those with high vs. low potential to serve as amplifying hosts for the virus. In general, mammals (primates, horses, companion animals) are d...
Hebia I, Fiéni F, Duchamp G, Destrumelle S, Pellerin JL, Zientara S, Vautherot JF, Bruyas JF.The objective of this study was to determine whether the 10 wash cycles proposed by the International Embryo Transfer Society (IETS) for bovine embryos efficiently decontaminated equine embryos exposed to equine herpes virus 1 (EHV-1) in vitro. Donor mares and stallions were individually screened and shown to be negative for the virus by PCR detection of EHV-1 DNA in blood leukocytes, semen, and uterine lavages in which embryos were recovered. Twenty embryos were recovered and randomly assigned to one of two groups: 10 embryos were exposed for 24h to infectious EHV-1 at 10(6)TCID(50)/ml, and 1...
Nishimoto KP, Laust AK, Wang K, Kamrud KI, Hubby B, Smith JF, Nelson EL.Dendritic cells (DCs) consist of heterogeneous phenotypic populations and have diverse immunostimulatory functions dependent on both lineage and functional phenotype, but as exceptionally potent antigen-presenting cells, they are targets for generating effective antigen-specific immune responses. A promising replicon particle vector derived from Venezuelan equine encephalitis virus (VEE) has been reported to transduce murine footpad DCs. However, the receptive DC subset, the degree of restriction for this tropism, and the extent of conservation between rodents and humans have not been well cha...
Wensman JJ, Thorén P, Hakhverdyan M, Belák S, Berg M.Borna disease virus (BDV) is a non-segmented, negative-stranded RNA virus, which infects cells of the central nervous system (CNS) in many different species. BDV is the causative agent of the neurological disorders in horses and sheep termed classical Borna disease (BD), as well as staggering disease in cats. At present, the diagnosis staggering disease or feline BD is made by histopathology or immunohistochemistry of the CNS. In order to obtain a better clinical diagnostic tool, a duplex real-time RT-PCR assay (rRT-PCR) was developed. TaqMan probes and primers specific for the BDV P and BDV L...
Craig MI, Barrandeguy ME, Fernández FM.Equine herpesvirus 2 (EHV-2) was isolated from healthy animals; therefore, the association between EHV-2 infection and respiratory disease raises the question of the role of this agent in this pathology. To date, there are no reports that relate viral excretion to health, this study then analysed 153 nasal swabs from horses in different age groups (older and younger than 1 year old) and state of health (clinically healthy and with respiratory symptoms). Results showed that the percentage of horses with viral excretion was higher within the clinically healthy group, being significative (p < 0.0...
Venter GJ, Koekemoer JJ, Paweska JT.Confirmed outbreaks of African horse sickness (AHS) occurred in the surveillance zone of the Western Cape in 1999 and 2004, both of which led to a two-year suspension on the export of horses. Light trap surveys in the outbreak areas showed that known vector competent Culicoides species, notably C. imicola, were abundant and present in numbers equal to those in the traditional AHS endemic areas. Isolations of AHS virus serotypes 1 and 7, equine encephalosis virus, and bluetongue virus from field-collected C. imicola in the surveillance zone demonstrated that this species was highly competent an...
Johnson S.West Nile virus affects many animals, but the highest prevalence of morbidity and mortality is observed in birds, horses, and humans. The purpose of this study was to determine a protocol in birds of prey and corvids, using a vaccine developed for horses. The birds were assigned to five groups. Groups 1-4 received 0.25 ml, 0.5 ml, 0.75 ml, and 1.0 ml, respectively, and group 5 served as a control group. The greatest percentage of seroconversion (58.3%) was observed in the vaccine group that received a dose of 1.0 ml administered thrice, 3 wk apart. This report demonstrates that a vaccine devel...
Balasuriya UBR, Snijder EJ, Heidner HW, Zhang J, Zevenhoven-Dobbe JC, Boone JD, McCollum WH, Timoney PJ, MacLachlan NJ.Strains of Equine arteritis virus (EAV) differ in the severity of the disease that they induce in horses. Infectious cDNA clones are potentially useful for identification of genetic determinants of EAV virulence; to date, two clones have been derived from a cell culture-adapted variant of the original (Bucyrus) isolate of EAV, and it has previously been shown that recombinant virus derived from one of these (rEAV030) is attenuated in horses. A complete cDNA copy of the genome of the virulent Bucyrus strain of EAV has now been assembled into a plasmid vector. In contrast to rEAV030, recombinant...
Sponseller BA, Sparks WO, Wannemuehler Y, Li Y, Antons AK, Oaks JL, Carpenter S.The principal neutralizing domain (PND) of equine infectious anemia virus (EIAV) is located in the V3 region of SU. Genetic variation in the PND is considered to play an important role in immune escape and EIAV persistence; however, few studies have characterized genetic variation in SU during the inapparent stage of disease. To better understand the mechanisms of virus persistence, we undertook a longitudinal study of SU variation in a pony experimentally inoculated with the virulent EIAV(Wyo). Viral RNA isolated from the inoculum and from sequential sera samples was amplified by RT-PCR, clon...
Dynon K, Black WD, Ficorilli N, Hartley CA, Studdert MJ.To examine the association of viruses with acute febrile respiratory disease in horses. Design Nasal swab and serum samples were collected from 20 horses with acute febrile upper respiratory disease that was clinically assessed to have a viral origin. Methods: Each of the samples was inoculated onto equine fetal kidney, RK13 and Vero cell cultures, and viral nucleic acid was extracted for polymerase chain reaction (PCR) or reverse transcription PCR. PCR primers were designed to amplify nucleic acid from viruses known to cause or be associated with acute febrile respiratory disease in horses in...
Echeverría MG, Díaz S, Metz GE, Serena MS, Panei CJ, Nosetto E.We report the nucleotide sequence and genetic diversity of four Equine Arteritis Virus (EAV) ORF 5 and 6 from Argentina isolates, obtained from asymptomatic virus-shedding stallions. Nucleic acid recovered from the isolates were amplified by RT-PCR and sequenced. Nucleotide and deduced amino acid sequences from the Argentine isolates were compared with 17 sequences available from the GenBank. Phylogenetic analysis revealed that the Argentine isolates grouped together in a definite cluster near European strains. Despite the greater genetic variability among ORF 5 from different isolates and str...
Diallo IS, Hewitson G, Wright LL, Kelly MA, Rodwell BJ, Corney BG.A multiplex real-time PCR was designed to detect and differentiate equid herpesvirus 1 (EHV-1) and equid herpesvirus 4 (EHV-4). The PCR targets the glycoprotein B gene of EHV-1 and EHV-4. Primers and probes were specific to each equine herpesvirus type and can be used in monoplex or multiplex PCRs, allowing the differentiation of these two closely related members of the Alphaherpesvirinae. The two probes were minor-groove binding probes (MGB) labelled with 6-carboxy-fluorescein (FAM) and VIC for detection of EHV-1 and EHV-4, respectively. Ten EHV-1 isolates, six EHV-1 positive clinical samples...
Minke JM, Toulemonde CE, Coupier H, Guigal PM, Dinic S, Sindle T, Jessett D, Black L, Bublot M, Pardo MC, Audonnet JC.To determine onset and duration of immunity provided by a 2- or 3-dose series of a new canarypox-vectored recombinant vaccine for equine influenza virus (rCP-EIV vaccine) expressing the hemagglutinin genes of influenza H3N8 virus strains A/eq/Kentucky/94 and A/eq/Newmarket/2/93 in ponies. Methods: Forty-nine 1- to 3-year-old male Welsh Mountain Ponies that were seronegative for equine influenza virus. Methods: Vaccinated and control ponies were challenged with aerosolized influenza virus A/eq/Sussex/89 (H3N8), representative of the Eurasian lineage of circulating influenza viruses. In trial 1,...
Aguilar PV, Weaver SC, Basler CF.Eastern equine encephalitis virus (EEEV) causes sporadic but often severe cases of human and equine neurological disease in North America. To determine how EEEV may evade innate immune responses, we screened individual EEEV proteins for the ability to rescue the growth of a Newcastle disease virus expressing green fluorescent protein (NDV-GFP) from the antiviral effects of interferon (IFN). Only expression of the EEEV capsid facilitated NDV-GFP replication. Inhibition of the antiviral effects of IFN by the capsid appears to occur through a general inhibition of cellular gene expression. For ex...
Rosas CT, Tischer BK, Perkins GA, Wagner B, Goodman LB, Osterrieder N.The immunogenicity in horses of a recombinant equine herpesvirus type 1 (EHV-1) vaccine expressing West Nile virus (WNV) prM and E proteins was studied. To construct the recombinant EHV-1, two-step en passant mutagenesis was employed for manipulation of a bacterial artificial chromosome (BAC) of vaccine strain RacH. Recombinant EHV-1 stably expressed the WNV prM and E proteins as demonstrated by indirect immunofluorescence and Western blotting. In addition, growth properties in vitro of the EHV-1/WNV recombinant were found to not be significantly different from those of the parental virus. To ...
MacLachlan NJ, Balasuriya UB, Davis NL, Collier M, Johnston RE, Ferraro GL, Guthrie AJ.Viral diseases constitute an ever growing threat to the horse industry worldwide because of the rapid movement of large numbers of horses for competition and breeding. A number of different types of vaccines are available for protective immunization of horses against viral diseases. Traditional inactivated and live-attenuated (modified live virus, MLV) virus vaccines remain popular and efficacious but recombinant vaccines are increasingly being developed and used, in part because of the perceived deficiencies of some existing products. New generation vaccines include MLVs with deletions and/or...
Garré B, van der Meulen K, Nugent J, Neyts J, Croubels S, De Backer P, Nauwynck H.Equine herpesvirus 1 (EHV-1) is an important equine pathogen that causes respiratory disease, abortion, neonatal death and paralysis. Although vaccines are available, they are not fully protective and outbreaks of disease may occur in vaccinated herds. Therefore, there is an urgent need for effective antiviral treatment. For three abortigenic (94P247, 97P70 and 99P96) and three neuropathogenic isolates (97P82, 99P136 and 03P37), the effect of acyclovir, ganciclovir, cidofovir, adefovir, 9-(2-phosphonylmethoxyethyl)-2,6-diaminopurine (PMEDAP) and foscarnet on plaque number was studied. Addition...
Postey RC, Appleyard GD, Kidney BA.Immunohistochemical (IHC) testing and electron microscopy have implicated Papillomavirus (PV) as the etiologic agent for equine papillomas and aural plaques, but Equine papillomavirus (EPV) DNA has yet to be demonstrated in these lesions by polymerase chain reaction (PCR). The purpose of this study was to evaluate formalin-fixed, paraffin-embedded tissues from naturally occurring cases of equine papillomas, aural plaques, and sarcoids for the presence of EPV DNA by means of PCR and for the presence of PV antigen by means of IHC testing. We used EPV-specific primers that amplified a region of 3...
Dauphin G, Zientara S.West Nile virus (WNV) is a mosquito-borne flavivirus, native to Africa, Europe, and Western Asia. In many respects, WNV is an outstanding example of a zoonotic pathogen that has leaped geographical barriers and can cause severe disease in human and horse. Before the emergence of WNV in the USA, only few methods of diagnosis were available. Recently, many changes in the fields of WN diagnosis and prevention have happened. This paper will review all these new tools. After a description of the main concerns in WNV and West Nile (WN) disease in humans and animals, this review will present the main...
Morales MA, Barrandeguy M, Fabbri C, Garcia JB, Vissani A, Trono K, Gutierrez G, Pigretti S, Menchaca H, Garrido N, Taylor N, Fernandez F, Levis S....West Nile virus (WNV) was isolated from the brains of 3 horses that died from encephalitis in February 2006. The horses were from different farms in central Argentina and had not traveled outside the country. This is the first isolation of WNV in South America.
Whalley JM, Ruitenberg KM, Sullivan K, Seshadri L, Hansen K, Birch D, Gilkerson JR, Wellington JE.Equine herpesviruses 1 and 4 (EHV-1 and EHV-4) cause equine respiratory disease worldwide. However, only EHV-1 is a cause of abortion and neurological disease, despite the two viruses having all 76 genes in common. In addition EHV-1 has a broader host range in cell culture than EHV-4, as exemplified by the rabbit kidney (RK) cell line that is permissive for EHV-1, but not for EHV-4. Here we describe that when EHV-4 produced in equine cells was inoculated onto RK cells expressing glycoprotein D of EHV-1 (RKgD1), infection developed as clusters of rounded cells, and this infectivity could be pas...
Poulet H, Minke J, Pardo MC, Juillard V, Nordgren B, Audonnet JC.The canarypox vaccine vector (ALVAC) technology has been used to develop and license several vaccines for companion animals and horses in the European Union and USA. ALVAC is a ubiquitous vector with high biosafety since it is non-replicative in mammalians, is genetically and physically stable, and able to induce both humoral and cell-mediated immune responses against the expressed transgene product. Specific rules apply for the development and registration of recombinant vector vaccines. The biology of the vector as well as the recombinant virus must be thoroughly documented to allow the risk...
Yuan Z, Gallagher A, Gault EA, Campo MS, Nasir L.Bovine papillomavirus (BPV) type 2 is involved in carcinogenesis of the urinary bladder in cattle, while BPV-1 is commonly associated with equine sarcoid tumours. In both cases the early viral proteins are expressed, but virion is not produced. Given the similarities in BPV biology between the tumours in cattle and horses, bovine bladder cancers and equine sarcoids were compared with respect to physical status, load of viral DNA and variability of the E5 open reading frame (ORF). Rolling circle amplification demonstrated that BPV-1 and BPV-2 genomes exist as double stranded, episomal, circular...
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...
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 ...
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...
Maury W, Thompson RJ, Jones Q, Bradley S, Denke T, Baccam P, Smazik M, Oaks JL.Equine infectious anemia virus (EIAV) is a lentivirus with in vivo cell tropism primarily for tissue macrophages; however, in vitro the virus can be adapted to fibroblasts and other cell types. Tropism adaptation is associated with both envelope and long terminal repeat (LTR) changes, and findings strongly suggest that these regions of the genome influence cell tropism and virulence. Furthermore, high levels of genetic variation have been well documented in both of these genomic regions. However, specific EIAV nucleotide or amino acid changes that are responsible for cell tropism changes have ...
Ibrahim el SM, Pagmajav O, Yamaguchi T, Matsumura T, Fukushi H.Nucleotide sequences of the intergenic region between ORF 62 and ORF 63 of equine herpesvirus 1 (EHV-1) isolates were analyzed. The sequences of this region consisted of variable and conserved domains among EHV-1 isolates. An EHV-1 mutant, Ab4-GFP, was constructed by inserting a green fluorescent protein (GFP) expression cassette flanked by lox P at both ends into the intergenic region between ORF 62 and ORF 63. Another mutant, Ab4-loxP, which contains one lox P site, was constructed by excision of the GFP cassette from the Ab4-GFP virus genome by cre enzyme. The recombinant Ab4-GFP formed sma...
Capomaccio S, Willand ZA, Cook SJ, Issel CJ, Santos EM, Reis JK, Cook RF.The genetically distinct wild horse herds inhabiting Shackleford Banks, North Carolina are probably the direct descendents of Spanish stock abandoned after failed attempts to settle mid-Atlantic coastal regions of North America in the Sixteenth Century. In a 1996 island survey, 41% of the gathered horses were discovered seropositive for Equine Infectious Anemia Virus (EIAV) with additional cases identified in 1997 and 1998. As a result of their unique genetic heritage, EIAV seropositive individuals identified in the two latter surveys were transferred to a quarantine facility on the mainland. ...
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 ...
Smith KC, Whitwell KE, Mumford JA, Hannant D, Blunden AS, Tearle JP.The V592 strain of equid herpesvirus-1 (EHV-1), which was originally isolated from a fetus during an abortion epizootic, has proved to be of low virulence in infection studies. Five Welsh Mountain pony mares and one foal were challenged intranasally or by aerosol with this isolate, and monitored clinically and virologically. All six animals shed virus in nasopharyngeal mucus, and viraemia was recorded from day 7 post-infection (PI). Pathological investigations revealed mild rhinitis and bronchiolitis in the mares, with viral antigen expression in degenerating epithelial cells of the nasal muco...
Hamblin C, Salt JS, Mellor PS, Graham SD, Smith PR, Wohlsein P.Investigations have been carried out to elucidate the possible role of the donkey in the epidemiology of African horse sickness (AHS). These studies have shown that despite the absence of pyrexia or other observable clinical signs, donkeys become infected with virulent AHS virus serotype 4 (AHSV 4) and that they develop a viraemia which can persist for at least 12 days, albeit at a comparatively lower titre than that recorded for similarly infected ponies. AHSV 4 showed a similar tissue tropism in the pony and donkey but the virus appeared to replicate less efficiently in donkey tissues. The o...
Harry TO, McCollum WH.The Bucyrus strain of equine arteritis virus, previously modified to avirulence and vaccinal virus by 131 serial passages in primary cell cultures of horse kidney followed by 111 passages in primary cell cultures of rabbit kidney, was further passaged in cultures of the E. Derm (NBL-6) cell line, a continuous diploid cell line. Pools of the 16th and 25th passages of the virus in this last equine dermal cell line were lyophilized and stored in lots at 37 C, 23 to 28 C, 4C, and -20 C. The viability of the vaccinal virus deteriorated rapidly during storage at 37 C and at 23 to 28 C, but was relat...
O'Rourke KI, Besola ML, McGuire TC.Proviral sequences in the peripheral blood mononuclear cells of 3 horses with acute equine infectious anemia virus were monitored using the polymerase chain reaction. Provirus was detected during the initial viremic episode in each horse and during each of 3 relapsing viremic cycles, although the appearance of provirus lagged behind the onset of viremia. Following each viremic episode, provirus levels in the peripheral monocytes decreased to less than 1 copy in 5 x 10(6) cells.
Agius CT, Studdert MJ.This chapter describes the molecular and biological properties of equine herpesviruses (EHV)2 and EHV5. It highlights advances in the study of EHV2 and EHV5. The reclassification of EHV2 and EHV5 as gammaherpesviruses rather than betaherpesviruses has profound implications for future approaches to the study of the two equine herpesviruses. The chapter places emphasis on a comparison between the properties of EHV2 and EHV5 and those of other gammaherpesviruses, especially Epstein-Barr virus (EBV), which is the causative agent of infectious mononucleosis/glandular fever in humans. Studies of the...
England JJ, Reed DE.Negative contrast electron microscopy (NCEM) was utilized as a routine tool in the diagnosis of viral infections of domestic and wild animals. Viruses identified by this technique were observed in infected culture systems or clinical specimens from several species including horses, cattle, sheep, dogs, cats, pigs, deer, Rocky Mountain bighorn sheep, antelope, and several avian species. Viruses were identified by NCEM based on their size, morphology, and symmetry and consisted of adenoviruses, herpesviruses, paramyxoviruses, myxoviruses, picornaviruses, parvoviruses, coronaviruses, reoviruses, ...
Afify AF, Hassanien RT, El Naggar RF, Rohaim MA, Munir M.Equid herpesviruses (EHVs) are a group of highly impactful viral pathogens that affect horses, presenting a substantial risk to the global equine industry. Among these, equid herpesvirus-1 (EHV-1) primarily causes respiratory infections. However, its ability to spread to distant organs can lead to severe consequences such as abortion and neurological diseases. These viruses can enter a dormant phase, with minimal activity, and later reactivate to trigger active infections at any time. Recently, there has been a notable rise in the prevalence of a particularly devastating strains of EHV-1 known...
Bruno L, Nappo MA, Frontoso R, Perrotta MG, Di Lecce R, Guarnieri C, Ferrari L, Corradi A.West Nile virus (WNV) is an important zoonotic pathogen belonging to the Flaviviridae family, which is endemic in some areas and emerging in others. WNV is transmitted by blood-sucking mosquitoes of the genus Culicoides, Aedes, and Anopheles, and the infection can cause different clinical symptoms. The most common and benign illness in humans is West Nile fever (WNF), but a lethal neurological disease (WNND), related to the neuro-invasiveness of WNV lineage 2, represents the highest health risk of WNV infection. The neuro-clinical form is recognized in mammals (land and cetaceans), particularl...
Diederich S, Babiuk S, Boshra H.Henipaviruses are single-stranded RNA viruses that have been shown to be virulent in several species, including humans, pigs, horses, and rodents. Isolated nearly 30 years ago, these viruses have been shown to be of particular concern to public health, as at least two members (Nipah and Hendra viruses) are highly virulent, as well as zoonotic, and are thus classified as BSL4 pathogens. Although only 5 members of this genus have been isolated and characterized, metagenomics analysis using animal fluids and tissues has demonstrated the existence of other novel henipaviruses, suggesting a far gre...
Gibbs EP.The most important neurotropic viral infections of the horse are the arthropod-borne encephalitides. These include Venezuelan encephalitis (VE), eastern encephalitis (EE) and western encephalitis (WE), which are found in the Americas, and Japanese B encephalitis which occurs in the Far East. All the viruses cause encephalitis in man. Between 1969 and 1972 an epidemic of VE occurred in Central America. In 1971 the disease was reported in Texas, where it was brought under control by the vaccination of susceptible horses with an attenuated live virus vaccine and by the reduction of the mosquito p...
Scherer WF, Anderson K, Pancake BA, Dickerman RW, Ordonez JV.Seventy-four strains of Venezuelan encephalitis (VE) virus recovered from sentinel hamsters or mosquitoes at enzootic habitats in Guatemala in the two years following the 1969 epidemic-equine epizootic were examined for ability to produce small plaques in Vero African green monkey kidney cell cultures, like isolates obtained during the epizootic. (a) One strain recovered from a sentinel hamster in late October 1969 at an enzootic habitat near the epicenter of the hemagglutination-inhibition (HI) and equine-virulence properties like epizootic virus; this strain retained its small plaque charact...
Zhang J, Go YY, MacLachlan NJ, Meade BJ, Timoney PJ, Balasuriya UB.Comparative sequence analysis of a series of strains of equine arteritis virus (EAV) of defined virulence for horses, ranging from the horse-adapted virulent Bucyrus (VB) strain to a fully attenuated vaccine strain derived from it, identified 13 amino acid substitutions associated with attenuation. These include 4 substitutions in the replicase proteins and 9 in the structural proteins. Using reverse genetic techniques, these amino acid substitutions were introduced into a virulent infectious cDNA clone pEAVrVBS derived from the VB strain of EAV. Inoculation of horses with the recombinant viru...
van Oirschot JT, Masurel N, Huffels AD, Anker WJ.Influenza virus A-equi 2(Heq2Neq2) caused an epizootic in the Netherlands in the winter of 1978-1979. Horses vaccinated with A/Equi/Praha/56 (HEq1Neq1) and A/Equi/Miami/63 (Heq2Neq2) were also infected and showed clinical signs. The virus involved showed a marked antigenic drift from the prototype and vaccine strain A/Equi/Miami/63 (Heq2Neq2). Infection of ferrets with the Dutch/79 isolates gave rise to high haemagglutination-inhibition antibody titres to a number of A-Equi 2-1963, 1968 and 1979 viruses. The incorporation of this virus into future influenza vaccines should be considered.
Mayo CE, Weyer CT, Carpenter MJ, Reed KJ, Rodgers CP, Lovett KM, Guthrie AJ, Mullens BA, Barker CM, Reisen WK, MacLachlan NJ.The availability of rapid, highly sensitive and specific molecular and serologic diagnostic assays, such as competitive enzyme-linked immunosorbent assay (cELISA), has expedited the diagnosis of emerging transboundary animal diseases, including bluetongue (BT) and African horse sickness (AHS), and facilitated more thorough characterisation of their epidemiology. The development of assays based on real-time, reverse-transcription polymerase chain reaction (RT-PCR) to detect and identify the numerous serotypes of BT virus (BTV) and AHS virus (AHSV) has aided in-depth studies of the epidemiology ...
Amat JAR, Patton V, Chauché C, Goldfarb D, Crispell J, Gu Q, Coburn AM, Gonzalez G, Mair D, Tong L, Martinez-Sobrido L, Marshall JF, Marchesi F....The mechanisms and consequences of genome evolution on viral fitness following host shifts are poorly understood. In addition, viral fitness -the ability of an organism to reproduce and survive- is multifactorial and thus difficult to quantify. Influenza A viruses (IAVs) circulate broadly among wild birds and have jumped into and become endemic in multiple mammalian hosts, including humans, pigs, dogs, seals, and horses. H3N8 equine influenza virus (EIV) is an endemic virus of horses that originated in birds and has been circulating uninterruptedly in equine populations since the early 1960s. ...
Tzipori S, Makin T, Smith M, Krautil F.Colostrum-deprived, colostrum-fed or suckling foals were orally inoculated with foal rotavirus and enterotoxigenic Escherichia coli derived from a calf. Neither agent given alone caused diarrhoea in foals aged 1 or 2 days, although with rotavirus, 2 of the 3 inoculated foals became depressed 3 days after inoculation and all 3 were excreting rotavirus in the faeces. Inoculation of both agents induced diarrhoea in colostrum-deprived, colostrum-fed or suckling foals aged up to 16 days. There was an apparent age-related resistance to diarrhoea which developed between 2 and 3 weeks of age. It was r...
