Omneity® Pellets
All-In-One Vitamin & Mineral Pellet
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.
Posttranscriptional effector domains in the Rev proteins of feline immunodeficiency virus and equine infectious anemia virus. By systematically dissecting the Rev proteins of feline immunodeficiency virus (FIV) and equine infectious anemia virus (EIAV), we have identified within each a short peptide that is functionally interchangeable with the effector domains found in Rev-like proteins from other retroviruses. The active sequences from FIV and EIAV differ in several respects from other known effectors and may represent a distinct class of effector domain.
Lentivirus cross-reactive determinants present in the capsid protein of equine infectious anaemia virus. In this study we used immune sera from equine infectious anaemia virus (EIAV)-infected horses which uniquely display broad reactivity with different lentivirus capsid proteins (CA) to characterize the cross-reactive determinants of lentivirus CA proteins. In particular, the role of the major homology region (MHR) of lentivirus CA proteins in this serological cross-reactivity was evaluated using both equine immune serum and murine monoclonal antibodies (MAbs) directed against the MHR segment of different lentiviruses. The results of our studies indicate that about 80% of sera from long-term exp...
Experimental transmission of eastern equine encephalitis virus by strains of Aedes albopictus and A. taeniorhynchus (Diptera: Culicidae). The vector competence of Aedes taeniorhynchus (Wiedemann) and four strains of Aedes albopictus (Skuse) was assessed for eastern equine encephalitis (EEE) virus isolated from Ae. albopictus collected in Polk County, Florida. Both species became infected with and transmitted EEE virus by bite after feeding on 1-d-old chicks that had been inoculated with EEE virus (viremia = 10(10.1) plaque-forming units [PFU] per ml of blood). However, when fed on an older chick with a lower viremia (viremia = 10(6.1) PFU per ml of blood), Ae. albopictus was significantly more susceptible to infection (90%, n = ...
Detection of African horse sickness virus by reverse transcription-PCR. Reverse transcription-PCR (RT-PCR) was used to detect African horse sickness virus (AHSV). A single primer pair which amplified a 423-bp fragment of the S8 gene which encodes the NS2 protein of AHSV was identified. Amplification of this fragment from all nine serotypes of AHSV was achieved with these primers. Between 10(1) and 10(2) copies of AHSV genomic double-stranded RNA could be detected by RT-PCR followed by agarose gel electrophoresis and ethidium bromide staining. Application of RT-PCR to blood samples from AHSV-infected horses resulted in earlier detection of viremia than virus isolat...
Enhancement of EIAV replication and disease by immunization with a baculovirus-expressed recombinant envelope surface glycoprotein. The potential for antibody-dependent enhancement of replication of macrophage/monocyte tropic viruses has posed a significant problem in the development of vaccines for several animal and human viruses and has raised significant concern in the design of potential AIDS vaccines. Using the previously described equine infectious anemia virus/Shetland pony system as a model for HIV-1 vaccine development, we have evaluated the efficacy of a recombinant subunit vaccine containing a baculovirus-expressed envelope surface glycoprotein (gp90) of EIAV. The results of these trials demonstrate not only th...
Natural vertical transmission of western equine encephalomyelitis virus in mosquitoes. The mechanism by which western equine encephalomyelitis (WEE) virus and other mosquito-borne alphaviruses (Togaviridae) survive during periods of vector inactivity is unknown. Recently, three strains of WEE virus were isolated from adult Aedes dorsalis collected as larvae from a salt marsh in a coastal region of California. This provides evidence of vertical transmission of WEE virus in mosquitoes in nature. Vertical transmission in Ae. dorsalis and closely related mosquito species may be an important mechanism for the maintenance of WEE virus in temperate regions in North America where horizo...
Characterization of A/eq-1 virus isolated during the equine influenza epidemic in India. The equine influenza virus, Ludhiana/5/87, isolated from the clinical material during the epidemic of equine influenza in India in 1987 was inhibited in haemagglutination-inhibition test by the antiserum against the prototype A/eq/Prague/1/56 (H7N7) virus and by post-epidemic horse sera. In haemagglutinin and neuraminidase analysis, the A/eq/Ludhiana/5/87 isolate appeared similar to the prototype A/eq/Prague/1/56 virus and was characterized as the H7N7 subtype.
The equine herpesvirus type 1 glycoprotein homologous to herpes simplex virus type 1 glycoprotein M is a major constituent of the virus particle. Glycoprotein 45 is a major envelope glycoprotein of equine herpesvirus type 1. The gene encoding this protein is located between map units 0.615 and 0.636 on the virus genome and evidence has suggested that it is encoded by gene 52, one of four genes within this region. Using PCR we have amplified gene 52 and subsequently cloned it into a mammalian expression vector under the control of the human cytomegalovirus immediate early gene promoter. The gene was expressed in COS-7 cells and its product was detected by immunofluorescence and Western blotting. The results indicate that glycoprotein 45 ...
Diagnosis of the African horse sickness virus serotype 4 by a one-tube, one manipulation RT-PCR reaction from infected organs. A single tube reverse transcription-polymerase chain reaction (RT-PCR) method for detection of African horse sickness virus (AHSV) in splenic tissues from infected horses is described. Double stranded RNA was extracted from infected organs of horses and used to produce complementary DNA (cDNA) with the two primers selected for the PCR. The 1179 bp amplified product (the segment 7 which encodes for VP 7), detected by electrophoresis on agarose gel and ethidium bromide staining, was hydrolysed with eight restriction endonucleases for characterization of the AHSV. The sensitivity of this method i...
[An outbreak of equine arteritis virus infection in a riding school]. A major part of the residing horses and ponies of a riding school in Noord-Holland became affected by a febrile disorder that included anorexia, depression, conjunctivitis, urticaria, edema of the legs and laborious locomotion. All remaining horses fell ill within one week. Based on the clinical symptoms the disorder was diagnosed as vasculitis. With serology the causative agent of the disorder appeared to be equine arteritis virus.
Evolution of alphaviruses in the eastern equine encephalomyelitis complex. Evolution of viruses in the eastern equine encephalomyelitis (EEE) complex was studied by analyzing RNA sequences and oligonucleotide fingerprints from isolates representing the North and South American antigenic varieties. By using homologous sequences of Venezuelan equine encephalomyelitis virus as an outgroup, phylogenetic trees revealed three main EEE virus monophyletic groups. A North American variety group included all isolates from North America and the Caribbean. One South American variety group included isolates from the Amazon basin in Brazil and Peru, while the other included strain...
Diagnosis of equine influenza by the polymerase chain reaction. Influenza A is a common respiratory infection of horses, and rapid diagnosis is important for its detection and control. Sensitive detection of influenza currently requires viral culture and is not always feasible. The polymerase chain reaction (PCR) was used to detect DNA produced by reverse transcription of equine influenza in stored nasal secretions, vaccines, and allantoic fluids. Primers directed at a target of 212 bp on conserved segment 7 (matrix gene) of human influenza A/Bangkok/1/79(H3N2) produced amplification products of appropriate size with influenza A/Equine/Prague/1/56 (H7N7), ...
Diagnosis of eastern equine encephalomyelitis virus infection in horses by immunoglobulin M and G capture enzyme-linked immunosorbent assay. Immunoglobulin M (IgM) and G (IgG) capture enzyme-linked immunosorbent assays (ELISAs) were used as possible adjuncts to hemagglutination inhibition (HI) and virus neutralization (VN) tests to differentiate between reaction to recent exposure to eastern equine encephalomyelitis (EEE) virus and those due to prior vaccination. Serum samples were evaluated by the IgM-capture ELISA, and the results were compared with those of HI and VN tests. Of 381 serum samples, 51% (195 samples) were positive by HI test (> or = 1:40) and 54% (205 samples) were positive by VN test (> or = 1:10), but only 3...
Inter- and intra-strain genomic variation in equine herpesvirus type 1 isolates. Restriction enzyme digests of DNA from 22 unselected isolates of EHV-1 were analysed by hybridization with cloned DNA fragments covering the genome. In addition to a small amount of inter-strain variation, heterogeneity within strains was observed, caused by loss of specific restriction endonuclease sites in the DNA of a proportion of the virus particles of any one stock. Fifteen strains demonstrated the same intra-strain variation involving loss of the BamHI L-M site which was shown to lie within coding sequence for the large subunit of ribonucleotide reductase. This particular mutation may t...
Equine herpesviruses 2 and 5: comparisons with other members of the subfamily gammaherpesvirinae. 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...
Identification of the activation domain of equine infectious anemia virus rev. Several members of the lentivirus family of complex retroviruses have been shown to encode proteins that are functionally equivalent to the Rev posttranscriptional regulatory protein of human immunodeficiency virus type 1 (HIV-1). Furthermore, the domain organization of HIV-1 Rev, featuring a highly basic N-terminal RNA binding domain and a leucin-rich C-terminal effector domain, has also been shown to be highly conserved among Rev proteins derived from not only the primate but also the ovine and caprine lentiviruses. Although it has therefore appeared highly probable that the lentivirus equin...
A rapid diagnostic assay for eastern equine encephalomyelitis viral RNA. Eastern equine encephalomyelitis virus (EEEV) has been a low-frequency, but serious human and veterinary health problem. Increased frequency of this mosquito-borne virus is anticipated as wetlands are maintained and re-established. Control of EEEV has depended on mosquito abatement in response to increasing frequency of EEEV in the environment. A coupled reverse transcription/polymerase chain reaction assay was designed to rapidly, sensitively, and specifically detect EEEV RNA. The assay successfully detected the viral RNA in a single-blind study of a set of field samples composed of either po...
The outbreak of equine influenza (H3N8) in the United Kingdom in 1989: diagnostic use of an antigen capture ELISA. In July 1989 influenza A/equine-2 (H3N8) was isolated from a nasopharyngeal swab taken from a non-thoroughbred horse exhibiting acute clinical respiratory disease. This was the first isolation of equine influenza virus in the United Kingdom since 1981. Subsequent investigations of acute respiratory disease in horses indicated that the infection was dispersed throughout the UK. However, unlike the previous epidemic of 1979, the first horses from which the virus was isolated had been vaccinated. This outbreak of influenza provided an opportunity to evaluate an antigen capture ELISA, directed aga...
The protective M proteins of the equine group C streptococci. The group C streptococci are the most commonly isolated bacteria from disease states in the horse. Important virulence factors of S. equi and S. zooepidemicus are the hyaluronic acid capsule and the antiphagocytic fibrillar M protein located on the surface of the cell wall and extending into and through the capsule. The hyaluronic acid capsule is non-antigenic and so is not involved in protective immunity. The M protein, a superantigen, elicits very strong B and T cell responses that may result in protective immunity mediated by opsonic antibodies in plasma and by locally synthesized IgG and I...
Local and systemic antibody production in horses affected with chronic obstructive pulmonary disease. An enzyme-linked immunosorbent assay (ELISA) was used to quantify isotype-specific antibody to Micropolyspora faeni and to Aspergillus fumigatus in the sera and bronchoalveolar lavage fluid (BALF) of normal horses, horses with chronic obstructive pulmonary disease (COPD) and horses with other chronic respiratory diseases. Elevated antibody levels were not detected in the sera of affected horses. However, both IgE and IgA antibody to both allergens was significantly elevated in BALF in COPD affected horses sampled both when symptomatic and asymptomatic. Elevated levels were also found in animal...
The effect of EHV-1 infection upon circulating leucocyte populations in the natural equine host. It has been suggested that EHV-1 infection may perturb immune responsiveness in the natural equine host. The mechanism underlying this phenomenon is not clear, but disturbances of circulating leucocyte populations could contribute. In order to objectively assess the nature of the haematological changes provoked by EHV-1 infection, two groups of conventionally-maintained Welsh mountain ponies were challenge-infected intra-nasally with the Ab4 isolate of EHV-1. These groups were controlled by similarly-sized groups of non-infected ponies. All data generated was subjected to rigorous statistical ...
Pathological changes associated with equine arteritis virus infection of the reproductive tract in prepubertal and peripubertal colts. The nature and extent of changes associated with equine arteritis virus (EAV) infection of the reproductive tract was documented in 21 prepubertal and 15 peripubertal colts. This study was part of an investigation into the relationship between stage of reproductive tract maturity and susceptibility to the experimental establishment of persistent infection with EAV. After intranasal challenge with a field isolate of EAV, all colts developed clinical signs of equine viral arteritis (EVA) from which they recovered rapidly. Clinical signs during the acute phase consisted of fever, serous to mucopu...
Equine abortion and stillbirth in central Kentucky during 1988 and 1989 foaling seasons. Pathologic and microbiologic examinations were performed on 1,211 aborted equine fetuses, stillborn foals, and placentas from premature foals in central Kentucky during the 1988 and 1989 foaling seasons to determine the causes of reproductive loss in the mare. Placentitis (19.4%) and dystocia-perinatal asphyxia (19.5%) were the 2 most important causes of equine reproductive loss. The other causes (in decreasing order) were contracted foal syndrome and other congenital anomalies (8.5%), twinning (6.1%), improper separation of placenta (4.7%), torsion of umbilical cord (4.5%), placental edema (4...
Isolation and identification of African horse sickness virus during an outbreak in Lagos, Nigeria. An outbreak of African horse sickness involving two horse stables in Lagos, Nigeria, was investigated. Inoculation of blood from infected horses into suckling albino mice resulted in isolation of a virus which was identified as African horse sickness virus by the complement fixation test. The clinical, pathological and epizootiological findings (reported elsewhere) were consistent with African horse sickness. Potential threats of the epidemic to international horse trade are briefly highlighted.
The isolation and identification of Potchefstroom virus: a new member of the equine encephalosis group of orbiviruses. Virus was isolated from the blood of horses (n = 5) showing fever and jaundice and was identified as equine encephalosis virus. In cross neutralisation tests, the isolates were shown to belong to a new serotype related to Gamil, one of the 6 known serotypes of equine encephalosis virus. The name Potchefstroom has been proposed for this new serotype.
Structural and functional characterization of rev-like transcripts of equine infectious anemia virus. Three cDNA clones representing structurally distinct transcripts were isolated from a cDNA library prepared from cells infected with equine infectious anemia virus (EIAV) by using a probe representing the S3 open reading frame, which is thought to encode Rev. One species, designated p2/2, contained four exons and was identical to a previously described polycistronic mRNA that encodes Tat. This transcript was predicted to also direct the synthesis of a truncated form of the transmembrane protein and a putative Rev protein whose N-terminal 29 amino acids, derived from env, are linked to S3 seque...
[The immunogenic properties of a recombinant vaccinia virus with an incorporated DNA copy of the 26S RNA of the Venezuelan equine encephalomyelitis virus]. A recombinant strain of vaccinia virus (VR26) containing a DNA-copy of the subgenomic 26S RNA of Venezuelan equine encephalomyelitis virus (VEE) inserted into the coding region of thymidine kinase (TK) gene was produced. This subgenomic RNA contained the genes for all structural proteins of the VEE virus, the strain Trinidad donkey (TRD). VR26 effectively expressed VEE virus glycoproteins on the membranes of the infected cells. Blood sera of VR26-immunized animals were found to contain VEE virus-specific antibodies. VR26-immunized mice and rabbits showed a high level of resistance to subcutane...
