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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.
Immunoprophylaxis against important virus disease of horses, farm animals and birds. 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...
Herpesviruses in respiratory liquids of horses: putative implication in airway inflammation and association with cytological features. 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...
In vivo evolution of the gp90 gene and consistently low plasma viral load during transient immune suppression demonstrate the safety of an attenuated equine infectious anemia virus (EIAV) vaccine. 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...
Experimental infection of potential reservoir hosts with Venezuelan equine encephalitis virus, Mexico. 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...
[Equine Infectious Anemia (EIA)]. Equine Infectious Anemia (EIA) is a reportable, eradicable epizootic disease caused by the equine lentivirus of the retrovirus family which affects equids only and occurs worldwide. The virus is transmitted by blood, mainly by sanguivorous insects. The main symptoms of the disease are pyrexia, apathy, loss of body condition and weight, anemia, edema and petechia. However, infected horses can also be inapparent carriers without any overt signs. The disease is diagnosed by serological tests like the Coggins test and ELISA tests. Presently, Switzerland is offi cially free from EIA. However, Switz...
Novel approach for detection of enteric viruses to enable syndrome surveillance of acute viral gastroenteritis. Acute gastroenteritis is one of the most common diseases worldwide, with viruses, particularly noroviruses, being the leading cause in developed countries. In The Netherlands, systematic surveillance of gastroenteritis outbreaks of suspected viral etiology was established by the National Institute for Public Health and the Environment in 1994. Since 2002, the total number of outbreaks reported has been increasing, and with that comes the need for sensitive assays that can be performed quickly. In addition, the diagnostic demand changed so that now the proportion of samples from hospitals is hi...
Influenza A viruses with truncated NS1 as modified live virus vaccines: pilot studies of safety and efficacy in horses. Three previously described NS1 mutant equine influenza viruses encoding carboxy-terminally truncated NS1 proteins are impaired in their ability to inhibit type I IFN production in vitro and are replication attenuated, and thus are candidates for use as a modified live influenza virus vaccine in the horse. Objective: One or more of these mutant viruses is safe when administered to horses, and recipient horses when challenged with wild-type influenza have reduced physiological and virological correlates of disease. Methods: Vaccination and challenge studies were done in horses, with measurement ...
Aggregation-associated loss of antigenicity observed for denatured virion protein 1 of Equine rhinitis A virus in an enzyme-linked immunosorbent assay. Equine rhinitis A virus (ERAV) is a picornavirus which causes an acute respiratory infection in horses worldwide, and virus neutralization (VN) has been the standard method for the detection of ERAV antibody in horse serum. Previous studies have identified recombinant virion protein VP1 (rVP1) purified under native conditions to be of high potential for the development of a diagnostic ERAV enzyme-linked immunosorbent assay (ELISA). This study presents an optimized protocol for the expression and purification of native full-length rVP1. Furthermore, we demonstrate that, upon denaturation, rVP1 ...
Field evaluation of a multiplex real-time reverse transcription polymerase chain reaction assay for detection of Vesicular stomatitis virus. Sporadic outbreaks of vesicular stomatitis (VS) in the United States result in significant economic losses for the U.S. livestock industries because VS is a reportable disease that clinically mimics foot-and-mouth disease. Rapid and accurate differentiation of these 2 diseases is critical because their consequences and control strategies differ radically. The objective of the current study was to field validate a 1-tube multiplexed real-time reverse transcription polymerase chain reaction (real-time RT-PCR) assay for the rapid detection of Vesicular stomatitis New Jersey virus and Vesicular st...
The continuous spread of West Nile virus (WNV): seroprevalence in asymptomatic horses. West Nile virus (WNV) was probably introduced in southern and northern Mexico from the USA in two independent events. Since then, WNV activity has been reported in several Mexican states bordering the USA and the Gulf of Mexico, but disease manifestations seen there in humans and equids are quite different to those observed in the USA. We have analysed WNV seroprevalence in asymptomatic, unvaccinated equids from two Mexican states where no data had been previously recorded. WNV IgG antibodies were detected in 31.6% (91/288) of equine sera from Chiapas and Puebla states (53.3% and 8.0%, respect...
Equine herpesvirus 1: characterisation of the first strain isolated in Colombia. This paper describes the isolation and characterisation of equine herpesvirus 1 (EHV-1) in Colombia. The virus was isolated from a nasal swab and an aborted foetus of a pregnant mare imported from Argentina, with clinical signs of rhinopneumonitis. The new strain was characterised through culture and morphological, serological and immunocytochemical studies. Polymerase chain reaction and DNA restriction maps revealed an EHV-1 1P genome. This is the first report on the isolation and characterisation of EHV-1 in Colombia.
Antigenic and genetic variations in European and North American equine influenza virus strains (H3N8) isolated from 2006 to 2007. Equine influenza virus (EIV) surveillance is important in the management of equine influenza. It provides data on circulating and newly emerging strains for vaccine strain selection. To this end, antigenic characterisation by haemaggluttination inhibition (HI) assay and phylogenetic analysis was carried out on 28 EIV strains isolated in North America and Europe during 2006 and 2007. In the UK, 20 viruses were isolated from 28 nasopharyngeal swabs that tested positive by enzyme-linked immunosorbent assay. All except two of the UK viruses were characterised as members of the Florida sublineage w...
Enzyme-linked immunosorbent assay using glycoprotein and monoclonal antibody for detecting antibodies to vesicular stomatitis virus serotype New Jersey. In this study, an enzyme-linked immunosorbent assay (ELISA) using glycoprotein and a monoclonal antibody (MAb) was developed for the detection of antibodies to vesicular stomatitis virus (VSV) serotype New Jersey (NJ). The glycoprotein to be used as a diagnostic antigen was extracted from partially purified VSV-NJ, and a neutralizing MAb specific to VSV-NJ was incorporated to compete with antibodies in a blocking ELISA using glycoprotein (GP ELISA). The cutoff of the GP ELISA was set at 40% inhibition, which corresponded to a virus neutralization test (VNT) titer of 32. With this threshold, th...
Evaluation of the presence of equine viral herpesvirus 1 (EHV-1) and equine viral herpesvirus 4 (EHV-4) DNA in stallion semen using polymerase chain reaction (PCR). In the horse, the risk of excretion of two major equine pathogens (equine herpesvirus types 1 (EHV-1) and 4 (EHV-4)) in semen is unknown. The objective of our study was to assess the possible risks for the horizontal transmission of equine rhinopneumonitis herpesviruses via the semen and the effect of the viruses on stallion fertility. Samples of stallion semen (n=390) were gathered from several different sources. Examination of the semen involved the detection of viral DNA using specific PCR. The mean fertility of the stallions whose sperm tested positive for viral DNA and the mean fertility ...
PCR detection of African horse sickness virus serogroup based on genome segment three sequence analysis. A nested reverse transcriptase (RT) polymerase chain reaction (RT-PCR), for rapid detection of African horse sickness virus (AHSV) double-stranded ribonucleic acid (dsRNA) in cell culture and tissue samples, was developed and evaluated. Using an outer pair of primers (P1 and P2), selected from genome segment three of AHSV serotype 6 (AHSV-6), the RT-PCR-based assay resulted in amplification of a 890 base pair (bp) primary PCR product. RNAs from the nine vaccine strains of AHSV, and a number of AHSV field isolates including the Central African isolates of AHSV-9 and AHSV-6, propagated in cell c...
[Comparison of proviral genomes between the Chinese EIAV donkey leukocyte-attenuated vaccine and its parental virulent strain]. The donkey leukocyte-attenuated vaccine of equine infectious anemia virus (EIAV) was the first lentiviral vaccine that induced solid protection from the infection of virulent strains. To elucidate the mechanism of increased immunogenicity and attenuated virulence of the vaccine, the proviral genomic DNA of an EIAV vaccine strain, EIAV(DLV121) was analyzed and compared with the genome of a parental virulent strain EIAV(DV117). Full length viral genomic DNAs were amplified as two segments by LA-PCR and were cloned. Because of the genomic diversity of retroviral quasispecies, 10 full-length seque...
Analysis of local spread of equine influenza in the Park Ridge region of Queensland. In 2007, an incursion of equine influenza (EI) occurred in Australia. Accurate maps of property boundaries were used to examine the pattern and mechanism of local spread of EI. This study focussed on a cluster of infected premises (IPs) at Park Ridge, a peri-urban suburb 26 km south of Brisbane, Queensland. The cluster recorded 437 IPs and 81% of these were not contiguous to a previously IP. The mean distance from each new IP to the closest previous IP was 0.85 +/- 1.50 km with a range of 0.01-12.94 km. Eighty-two percent of new IPs were within 1 km of a previous IP. The spatial mean for each ...
[Epidemiological investigation on natural infection to Borna disease virus (BDV) among horses in Yili, Xinjiang]. To investigate the epidemiological pattern of Borna disease virus (BDV) infection in horses and to analyze the phylogenetic tree of derived BDV in Yili, Xinjiang. Methods: We established a modified nested RT-PCR (nRT-PCR) to detect BDV p24 segment in peripheral blood mononuclear cells (PBMCs) and brain tissues of 120 horses in Yili, Xinjiang. Positive products were analyzed by sequencing and homology analysis. Results: The positive rate of BDV infection was 2.5% in both PMBCs and brain tissues at the same time. The gene sequence revealed in positive PCR samples was more than 93%, identical to ...
Glycoprofile of the different cell types present in the mucosa of the horse guttural pouches. Histochemical characterization of the equine guttural pouches was performed using lectins combined with sialidase digestion and deglycosylation pre-treatments. The goblet cells contained O- and N-linked oligosaccharides with alpha-Fuc, GlcNAc moieties whereas beta-GalNAc, beta-Gal-(1-3)-GalNAc, beta-Gal-(1-4)-GlcNAc and alpha-Gal residues belonged only to O-linked glycoproteins. The acinar and ductal cells expressed alpha-Man/alpha-Glc in N-linked oligosaccharides, GlcNAc in both O- and N-glycoproteins and beta-GalNAc, beta-Gal-(1-3)-GalNAc, beta-Gal-(1-4)-GlcNAc and alpha-Gal residues include...
Immune response against equine gammaherpesvirus in Icelandic horses. Horses are hosts to two types of gammaherpesviruses, equine herpes virus (EHV) 2 and 5. While EHV-2 is ubiquitous in adult horses, EHV-5 has been less frequently described. Due to strong serological cross-reactivity, EHV-2 and -5 cannot be discriminated in broad spectrum antibody tests and are thus commonly referred to as gamma-EHV. Total IgG and IgG subclass response against gamma-EHV were determined in serum from 41 healthy Icelandic horses, thereof 20 adults, 10 foals aged 10 months, and 11 foals aged 1-4 months. Additionally, in 10 of the adult horses, interferon (IFN)-gamma and interleuki...
Structural model of the Rev regulatory protein from equine infectious anemia virus. Rev is an essential regulatory protein in the equine infectious anemia virus (EIAV) and other lentiviruses, including HIV-1. It binds incompletely spliced viral mRNAs and shuttles them from the nucleus to the cytoplasm, a critical prerequisite for the production of viral structural proteins and genomic RNA. Despite its important role in production of infectious virus, the development of antiviral therapies directed against Rev has been hampered by the lack of an experimentally-determined structure of the full length protein. We have used a combined computational and biochemical approach to gen...
A highly sensitive method for the detection and genotyping of West Nile virus by real-time PCR. In recent years, West Nile virus has been responsible for outbreaks in regions where it has not previously been found. Five genetic lineages with specific geographic distributions exist. Recent outbreaks of WNV associated with the introduction of lineage 1 strains into the western hemisphere, together with the emergence of lineage 2 WNV in Central Europe, has highlighted the potential for spread of pathogenic WNV strains beyond their expected geographical boundaries. Therefore, genotyping of WNV strains may have important applications in surveillance and epidemiology. We report here the develo...
Effective treatment of respiratory alphaherpesvirus infection using RNA interference. Equine herpesvirus type 1 (EHV-1), a member of the Alphaherpesvirinae, is spread via nasal secretions and causes respiratory disease, neurological disorders and abortions. The virus is a significant equine pathogen, but current EHV-1 vaccines are only partially protective and effective metaphylactic and therapeutic agents are not available. Small interfering RNAs (siRNA's), delivered intranasally, could prove a valuable alternative for infection control. siRNA's against two essential EHV-1 genes, encoding the viral helicase (Ori) and glycoprotein B, were evaluated for their potential to decrea...
Isolation and characterization of the equine influenza virus causing the 2006 outbreak in Chile. The equine influenza virus is the causal agent of influenza in horses. In July 2006, horses from various regions of Chile presented fever, serious nasal discharge, dry cough, anorexia and depression. Here we describe the isolation and characterization of the virus responsible for this outbreak. The virus was identified as equine influenza virus H3N8, since haemagglutination was inhibited by an anti-A/equi/1/H3N8 serum, but not by an anti-A/equi/1/H7N7 serum. The isolate was named A/equi/2/Lonquén/06 (H3N8). In addition, we describe the isolation and sequencing of the haemagglutinin, neuramini...
Virion associated proteins of equine rhinitis B virus 1 (ERBV1): the non-structural protein 3C(pro) co-purifies with virions. Equine rhinitis B virus (ERBV), genus Erbovirus, is most closely related to the Cardiovirus genus in the family Picornaviridae. The structural proteins (VP1-4) of erboviruses are not well described, but are predicted by sequence to be 35, 29, 26 and 7 kDa. Methods for the purification of cardioviruses (polyethylene glycol, trypsin treatment) were used to characterise the structural proteins of ERBV1. Only one of the virus proteins detected was an expected molecular mass, and this 26 kDa protein was identified as VP3 by N-terminal amino acid sequencing. N-terminal sequencing of the 56 and a 29 ...
Real-time RT-PCR for detection of equine influenza and evaluation using samples from horses infected with A/equine/Sydney/2007 (H3N8). Equine influenza (EI) virus (H3N8) was identified in the Australian horse population for the first time in August 2007. The principal molecular diagnostic tool used for detection was a TaqMan real-time reverse transcription-polymerase chain reactions (RT-PCR) assay specific for the matrix (MA) gene of influenza virus type A (IVA). As this assay is not specific for EI, we developed a new EI H3-specific TaqMan assay targeting the haemagglutinin (HA) gene of all recent EI H3 strains. The IVA and the EI H3 TaqMan assays were assessed using in vitro transcribed RNA template, virus culture, diagnost...
Serosurveillance for Japanese encephalitis, Akabane, and Aino viruses for Thoroughbred horses in Korea. Recent global warming trends may have a significant impact on vector-borne viral diseases, possibly affecting vector population dynamics and disease transmission. This study measured levels of hemagglutination-inhibition (HI) antibodies against Japanese encephalitis virus (JEV) and neutralizing antibodies against Akabane virus (AKAV) and Aino virus (AINV) for Thoroughbred horses in Korea. Blood samples were collected from 989 racehorses in several provinces, between October 2005 and March 2007. Sera were tested using either an HI assay or a virus neutralization test. Approximately half (49.7%;...
