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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.
Regulation of equine herpesvirus type 1 gene expression: characterization of immediate early, early, and late transcription. The regulation of equine herpesvirus type 1 (EHV-1) transcription was examined in infected rabbit kidney cells using metabolic inhibitors. In order to map EHV-1 immediate early, early, and late transcripts, viral RNA was 32P-labeled in vivo and hybridized to EHV-1 DNA restriction fragments immobilized on nitrocellulose filters. Immediate early viral RNA was mapped to one region of the viral genome within the inverted repeat DNA sequences (map units 0.78-0.83 and 0.95-1.0). Northern blot hybridization analysis using a 32P-labeled cloned DNA probe from this region identified a single immediate e...
Genomic heterogeneity of equine betaherpesviruses. The genomes of 51 isolates of slowly cytopathic equine herpesviruses were examined by digestion with restriction endonucleases. Forty-seven of the isolates showed considerable fragment pattern heterogeneity although common fragments were evident, especially when any two isolates were compared or when they were digested with SalI. Fifteen of the 47 viruses, selected for their diverse fragment patterns, showed a high degree of homology in Southern blot hybridization. In contrast, four viruses, representing three epidemiologically distinct isolations, shared few, if any, comigrating fragments wit...
Course and extent of variation of equine infectious anemia virus during parallel persistent infections. Comparisons of peptide and oligonucleotide maps of glycoproteins and RNA from nine isolates of equine infectious anemia virus (EIAV) that were generated during parallel infections of two Shetland ponies revealed that each isolate was structurally unique. Each EIAV isolate contained a unique subset of variant peptides, oligonucleotides, or both, indicating that structural variation in EIAV is a random and noncumulative process and that a large spectrum of possible EIAV variants can be generated in infected animals.
Comparison of naturally occurring poliovirus-reactive immunoglobulins in bovine and equine sera. Bovine and equine sera were screened for poliovirus-reactive immunoglobulins (PRIgs) by means of neutralization and precipitation reactions with type 1 poliovirus. Bovine serum B1826 and B36 were found to contain such PRIgs from their reactivity to various PRIgs-resistant mutants of type 1 poliovirus origin. Neutralization and precipitation reactions with six mono-specific antibodies obtained by absorbing antiserum with each of the six different PRIgs-resistant virus mutants revealed that three antibodies were active in precipitation reaction while the others were substantially ineffective. On...
Characterization of equine infectious anemia virus long terminal repeat. The long terminal repeats (LTRs) of equine infectious anemia virus (EIAV) were examined with respect to their ability to function as transcriptional promoters in various cellular environments. Nucleotide sequence analyses of the LTRs derived from two unique proviral clones revealed the requisite consensus transcription and processing signals. One of the proviruses possessed a duplication of a 16-base-pair sequence in the CCAAT box region of the LTR which was absent in the other provirus. To assess its functional activity, each LTR was coupled to the bacterial chloramphenicol acetyltransferase ...
Infection of a poikilothermic cell line (XL-2) with eastern equine encephalitis and western equine encephalitis viruses. Eastern Equine Encephalitis (EEE) was in Cuba before the 1940s; the virus has been isolated from horses, birds, and rodents during epizootic as well as interepizootic periods. The only isolation of Western Equine Encephalitis (WEE) virus was from a sick pigeon found in the vicinity of Havana University. Both viruses can cause human disease; the isolation of WEE virus from the centre of an urban area emphasises the need for the prompt isolation and rapid identification of these agents. The object of this work was to compare the sensitivity of a continuous cell line (XL-2) from the toad, Xenopus...
Hybridoma cell lines secreting monoclonal antibodies against equine infectious anemia virus. A monoclonal anti-equine infectious anemia virus (anti-EIAV) antibody (1B15) has been generated by fusion of X63 Ag 8.653 myeloma cells and spleen cells from mice hypersensitized with viral antigen p29. Ouchterlony double-diffusion analysis indicated that antibody 1B15 is of the IgG class. The specificity of the immune reaction for p29 was confirmed by cross-over immunoelectrophoresis and disc-gel electrophoresis. MAb 1B15 was used to devise a solid-phase 'capture' RIA for EIAV-p29 antigen. The antigen, bound by 1B15 adsorbed onto wells of flexible microtitre plates, was detected using a rabbi...
The experimental infection of horses with Murray Valley encephalitis and Ross River viruses. Eleven weanling horses were inoculated with Murray Valley encephalitis and Ross River viruses either by intravenous injection or by the bite of Culex annulirostris or Aedes vigilax mosquitoes infected orally. Five of the 11 horses circulated trace amounts of MVE virus for 1 to 5d and they infected 7/408 Cx annulirostris which subsequently fed on them. Haemagglutination-inhibiting antibody persisted at detectable levels for the 24-week observation period. With Ross River virus, only one of 11 horses inoculated developed a viraemia detectable by inoculation of suckling mice but 5 horses containe...
[New observations in the diagnosis of EHV (equine herpes virus) abortions]. Over the last years the percentage of foals lost by EHV at term or close to term seems to be higher than in former years. Furthermore, the pathological findings seem to shift from liver to lung. So far there has been no explanation for this phenomenon.
Susceptibility of various cell culture systems to pseudorabies virus. A comparative study was carried out to determine the susceptibility of five different cell lines to pseudorabies virus (PRV), a herpes virus of pigs. The cell systems tested were swine testicle (ST), mink lung (ML), equine dermal (ED), porcine kidney (PK15), and bovine turbinate (BT) cells. Virus titers obtained were 10(4.88), 10(4.38), 10(3.75), 10(2.63), and 10(0.25) for ML, ST, PK15, BT and ED cells, respectively indicating that ML, ST, and PK15 are optimal cell lines for the growth of PRV whereas BT and ED are not very sensitive.
The carrier state in equine arteritis virus infection in the stallion with specific emphasis on the venereal mode of virus transmission. The carrier state has been confirmed virologically in Thoroughbred and non-Thoroughbred stallions naturally infected with equine arteritis virus (EAV). Short-term or convalescent and long-term carriers occur. The frequency rate of the long-term carrier state in Thoroughbreds was high, averaging 33.9% among the three groups of stallions under study. While the convalescent carrier state only lasted a few weeks after clinical recovery, the long-term carrier state could persist for years. There was evidence, however, that not all such carriers might remain persistently infected for life. Carrier s...
Complement-mediated hemolysis of horse erythrocytes treated with equine infectious anemia virus. Horse erythrocytes treated with equine infectious anemia virus hemagglutinin were found to be lysed after incubation with fresh horse serum at 37 degrees C. Fresh guinea pig serum induced more efficient hemolysis than horse serum. Direct immunofluorescence test revealed the adsorption of complement factors on the surface of the erythrocytes. Calcium and magnesium ions were necessary for the hemolysis to take place. Antibody against equine infectious anemia virus enhanced the virus-induced complement-mediated hemolysis. These observations indicated that the classical pathway of complement activ...
Epizootic vesicular stomatitis in Colorado, 1982: epidemiologic studies along the northern Colorado front range. Epidemiologic evaluations were made of farm personnel on vesicular stomatitis-affected premises along the front range of the Rocky Mountains in Colorado during the 1982 epizootic. A similar antibody prevalence was noted to that of veterinarians and research and regulatory personnel who were involved with the same epizootic. Risk of infection resulted from intimate physical contact with infected horses or cows. Incidence and infection rates in horses were 45%; rates in cows were much lower, only 5%. Some epidemiologic clues were gained by a detailed study of an equine ranch. The pasture was inc...
The proteins of equid herpesvirus 1 (EHV 1) recognised by equine antisera and their ability to promote antibody-dependent cell-mediated cytotoxicity. Equine sera were used to immunoprecipitate radiolabelled virus-infected cell proteins; subsequent resolution with polyacrylamide gel electrophoresis identified the EHV-1 polypeptides VP 2, 10a, 11, 13, 14, 15, 16, 20, 21 and 23a. The humoral support of ADCC by these sera was examined in vitro. Cytotoxicity could be demonstrated against both subtypes irrespective of the immunising isolate. The implications of these results are discussed.
Plasma concentrations of progestagens, oestrone sulphate and prolactin in pregnant mares subjected to natural challenge with equid herpesvirus-1. Multiparous pregnant mares, on two studfarms, were studied following natural challenge with equid herpesvirus-1 (EHV-1). They were divided into three groups according to serum complement fixation titres: Group A (N = 11) were not challenged and delivered normal foals; Group B (N = 13) were challenged but delivered normal foals; Group C (N = 23) were challenged and delivered infected foals which were stillborn or lived for less than 31 h. In Groups A and B mean (+/- s.d.) gestational age at delivery was 343 (+/- 8) and 339 (+/- 8) days respectively, whereas in Group C it was significantly (P le...
A newly recognized vesiculovirus, Calchaqui virus, and subtypes of Melao and Maguari viruses from Argentina, with serologic evidence for infections of humans and horses. In 1983, 17 virus strains were isolated from mosquitoes collected during an outbreak of western equine encephalitis in Santa Fe Province, Argentina. Strains of western equine encephalitis, Venezuelan equine encephalitis, St. Louis encephalitis, and Antequera viruses were isolated, as were several bunyaviruses of the California and Bunyamwera serogroups and a new vesiculovirus. Complement fixation and neutralization tests were used to identify the California serogroup virus as a subtype of Melao virus, the Bunyamwera serogroup virus as a subtype of both Maguari and Playas viruses, and the vesic...
Serological and virological investigations of an equid herpesvirus 1 (EHV-1) abortion storm on a stud farm in 1985. An extensive outbreak of EHV-1 abortions occurred on a stud farm in England in 1985. Of the 67 pregnant mares present on the stud farm, 31 were challenged with EHV-1, resulting in the loss of 22 fetuses or foals. Laboratory investigations revealed that the spread of the virus closely followed movement of apparently healthy mares (during the incubation period of the infection). During the outbreak mares were challenged 1-4 months before the expected foaling date. There was no relationship between the gestational age at the time of challenge and the subsequent outcome of infection in terms of ab...
Molecular pathogenesis of equine coital exanthema (ECE): temperature sensitivity (TS) and restriction endonuclease (RE) fragment profiles of several field isolates. Examination of six field isolates of equine herpesvirus 3, the causative agent of equine coital exanthema, indicates that all were temperature sensitive (ts) at the body temperature, 39 degrees C, of their host (Equine asinus and callabus) when grown in cell culture. The isolates were characterized by fingerprint analysis with the restriction endonucleases XbaI, EcoRI, BamHI and Hind III to establish possible epidemiologic relatedness. Three of the six isolates may be considered related. Variation in the mobility of the BamHI-A and Hind III-K fragments indicates that a small plaque isolate may...
Epidemiology of equine herpesvirus 2 (equine cytomegalovirus). The epidemiology of equine herpesvirus 2 was examined by using restriction endonuclease DNA fingerprints to distinguish viruses isolated from two groups of horses. The first group consisted of three yearlings isolated from other horses but in contact with each other for 418 days, whereas the second comprised seven mares and their foals, which were sampled at monthly intervals from parturition until the foals were about 180 days old. There was a complex pattern of transmission, with 15 different viruses isolated from both groups. Four distinguishable viruses were isolated from the three yearlin...
Phagocytosis of horse erythrocytes treated with equine infectious anemia virus by cultivated horse leukocytes. Horse erythrocytes treated with equine infectious anemia virus hemagglutinin were phagocytized by cultivated horse leukocytes (mainly macrophage-like cells and partly polymorphonuclear cells) after incubation with fresh horse serum but not with inactivated horse serum. The phagocytosis began as soon as the erythrocytes were added to the leukocyte cultures, and the majority of the reaction proceeded within 30 minutes. Addition of antiserum showed a slightly suppressing but no enhancing effect on the phagocytosis. Phagocytosis seemed to be caused by the recognition of the third complement compon...
Arbovirus isolations from mosquitoes collected during and after the 1982-1983 epizootic of western equine encephalitis in Argentina. Mosquitoes were collected in Santa Fe and Rio Negro provinces, Argentina, in 1982-1983 during a western equine encephalitis (WEE) epizootic. Totals of 153,084 mosquitoes from Santa Fe Province and 484 from Rio Negro Province were tested for virus in 2,351 pools. Seventeen virus strains were isolated, all from Santa Fe collections, as follows: 4 WEE, 6 Venezuelan equine encephalitis, 1 St. Louis encephalitis, 2 Antequera, 1 Maguari, 1 Melao, 1 new vesiculovirus (Calchaqui), and 1 Gamboa. The WEE virus isolates were from Aedes albifasciatus, Anopheles albitarsis, Mansonia species, and Psorophora...
[Differentiation of equine influenza viruses subtype 2 with monoclonal antibodies]. Infections and clinical diseases caused by equine 2 influenza A viruses are observed worldwide. The frequency of these outbreaks supports the hypothesis that antigenic variation of the surface proteins may play an important role. For the demonstration of these variations, monoclonal antibodies (Mabs) were prepared. They are directed against the hemagglutinin or the neuraminidase of the prototype strain a/eq/Miami/1/63. In hemagglutination-inhibition assays with Mabs two reaction patterns were observed: four Mabs inhibited 14 out of 17 strains tested. Another Mab recognized the hemagglutinin of...
Epizootic vesicular stomatitis in Colorado, 1982: infection in occupational risk groups. In 1982-1983, an epizootic of vesicular stomatitis occurred in the western United States. Veterinarians, research workers, and regulatory personnel who were exposed to vesicular stomatitis virus were examined for patterns of human infection and prevalence of vesicular stomatitis New Jersey serotype neutralizing antibody. Insight into the mechanism of transmission was sought by comparing activities of antibody-positive and antibody-negative persons. A statistically significant risk factor was a history of infected animals sneezing in the face of serosurvey participants. Elevated odds ratios wer...
