Prevalence of latent alpha-herpesviruses in Thoroughbred racing horses.
Abstract: The objective of this study was to detect and characterize latent equine herpes virus (EHV)-1 and -4 from the submandibular (SMLN) and bronchial lymph (BLN) nodes, as well as from the trigeminal ganglia (TG) of 70 racing Thoroughbred horses submitted for necropsy following sustaining serious musculoskeletal injuries while racing. A combination of nucleic acid precipitation and pre-amplification steps was used to increase analytical sensitivity. Tissues were deemed positive for latent EHV-1 and/or -4 infection when found PCR positive for the corresponding glycoprotein B (gB) gene in the absence of detectable late structural protein gene (gB gene) mRNA. The EHV-1 genotype was also determined using a discriminatory real-time PCR assay targeting the DNA polymerase gene (ORF 30). Eighteen (25.7%) and 58 (82.8%) horses were PCR positive for the gB gene of EHV-1 and -4, respectively, in at least one of the three tissues sampled. Twelve horses were dually infected with EHV-1 and -4, two carried a latent neurotropic strain of EHV-1, six carried a non-neurotropic genotype of EHV-1 and 10 were dually infected with neurotropic and non-neurotropic EHV-1. The distribution of latent EHV-1 and -4 infection varied in the samples, with the TG found to be most commonly infected. Overall, non-neurotropic strains were more frequently detected than neurotropic strains, supporting the general consensus that non-neurotropic strains are more prevalent in horse populations, and hence the uncommon occurrence of equine herpes myeloencephalopathy.
Copyright © 2012 Elsevier Ltd. All rights reserved.
Publication Date: 2012-03-10 PubMed ID: 22405721DOI: 10.1016/j.tvjl.2012.01.030Google Scholar: Lookup
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- Journal Article
Summary
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This study investigated the prevalence of latent equine herpes virus (EHV)-1 and EHV-4 in Thoroughbred racing horses and found that a vast majority were infected, though the non-neurotropic strains of these viruses were most common, explaining the rarity of equine herpes myeloencephalopathy.
Objective and Methodology
- The objective of the study was to detect and characterize latent infection of two alpha-herpesvirus, namely EHV-1 and EHV-4, in Thoroughbred racing horses.
- The researchers obtained samples from submandibular (SMLN) and bronchial lymph nodes (BLN), as well as the trigeminal ganglia (TG) of 70 horses that were subjected to necropsy.
- To increase the sensitivity of detection, nucleic acid precipitation and pre-amplification steps were used.
- Positive infection was confirmed if tissues tested PCR positive for the glycoprotein B (gB) gene of either virus, without detectable mRNA for the same gene. This indicated a dormant infection as the gB gene is a late-expressed gene in the viral lifecycle.
- The study also differentiated between different genotypes of EHV-1, determining if they were neurotropic (capable of infecting nerve cells) or non-neurotropic (not able to infect nerve cells).
Findings
- 18 of the 70 horses (25.7%) were found to be infected with EHV-1 and 58 (82.8%) with EHV-4 based on detection of the gB gene in at least one of the three tissues sampled.
- 12 horses were found to be co-infected with both EHV-1 and EHV-4, and two of these had the neurotropic strain of EHV-1.
- Six horses carried the non-neurotropic EHV-1 strain, while 10 horses had dual infection with both neurotropic and non-neurotropic EHV-1.
- The distribution of infection varied across the three tissues sampled, with the TG being the most commonly infected site.
Conclusions
- The study concluded that non-neurotropic strains of the equine herpes viruses were more prevalent, which supports the general consensus in scientific communities. This may explain the reason why equine herpes myeloencephalopathy, a condition caused by neurotropic strains of the virus, is a rare occurrence.
- The findings of this research contribute to the understanding of herpes virus prevalence and infection pattern in Thoroughbred racing horses and may influence the development of preventative and control strategies in the future.
Cite This Article
APA
Pusterla N, Mapes S, David Wilson W.
(2012).
Prevalence of latent alpha-herpesviruses in Thoroughbred racing horses.
Vet J, 193(2), 579-582.
https://doi.org/10.1016/j.tvjl.2012.01.030 Publication
Researcher Affiliations
- Department of Veterinary Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA. npusterla@ucdavis.edu
MeSH Terms
- Animals
- Bronchi / virology
- California / epidemiology
- DNA, Viral / genetics
- Female
- Herpesviridae Infections / epidemiology
- Herpesviridae Infections / veterinary
- Herpesviridae Infections / virology
- Herpesvirus 1, Equid / isolation & purification
- Herpesvirus 1, Equid / physiology
- Herpesvirus 4, Equid / isolation & purification
- Herpesvirus 4, Equid / physiology
- Horse Diseases / epidemiology
- Horse Diseases / virology
- Horses
- Lymph Nodes / virology
- Male
- Mandible / virology
- Pedigree
- Prevalence
- Real-Time Polymerase Chain Reaction / veterinary
- Trigeminal Ganglion / virology
- Virus Latency
Citations
This article has been cited 12 times.- Nielsen SS, Alvarez J, Bicout DJ, Calistri P, Canali E, Drewe JA, Garin-Bastuji B, Gonzales Rojas JL, Gortázar C, Herskin M, Michel V, Miranda Chueca MÁ, Roberts HC, Padalino B, Pasquali P, Spoolder H, Ståhl K, Calvo AV, Viltrop A, Winckler C, Carvelli A, Paillot R, Broglia A, Kohnle L, Baldinelli F, Van der Stede Y. Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU) No 2016/429): infection with Equine Herpesvirus-1. EFSA J 2022 Jan;20(1):e07036.
- Samoilowa S, Giessler KS, Torres CEM, Hussey GS, Allum A, Fux R, Jerke C, Kiupel M, Matiasek K, Sledge DG, Goehring LS. Equid herpesvirus-1 Distribution in Equine Lymphoid and Neural Tissues 70 Days Post Infection. Pathogens 2021 Jun 5;10(6).
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- Lechmann J, Schoster A, Ernstberger M, Fouché N, Fraefel C, Bachofen C. A novel PCR protocol for detection and differentiation of neuropathogenic and non-neuropathogenic equid alphaherpesvirus 1. J Vet Diagn Invest 2019 Sep;31(5):696-703.
- Wimer CL, Schnabel CL, Perkins G, Babasyan S, Freer H, Stout AE, Rollins A, Osterrieder N, Goodman LB, Glaser A, Wagner B. The deletion of the ORF1 and ORF71 genes reduces virulence of the neuropathogenic EHV-1 strain Ab4 without compromising host immunity in horses. PLoS One 2018;13(11):e0206679.
- Schnabel CL, Wimer CL, Perkins G, Babasyan S, Freer H, Watts C, Rollins A, Osterrieder N, Wagner B. Deletion of the ORF2 gene of the neuropathogenic equine herpesvirus type 1 strain Ab4 reduces virulence while maintaining strong immunogenicity. BMC Vet Res 2018 Aug 22;14(1):245.
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- Tallmadge RL, Laverack M, Lejeune M, Crossley B, Diel DG. A multiplex real-time PCR assay for detection of equid herpesvirus 1 and 4. Sci Rep 2025 Oct 31;15(1):38201.
- Ryt-Hansen P, Johansen VK, Cuicani MM, Larsen LE, Hansen S. Outbreak of equine herpesvirus 4 (EHV-4) in Denmark: tracing patient zero and viral characterization. BMC Vet Res 2024 Jul 3;20(1):287.
- Öhrmalm J, Cholleti H, Theelke AK, Berg M, Gröndahl G. Divergent strains of EHV-1 in Swedish outbreaks during 2012 to 2021. BMC Vet Res 2024 Jun 22;20(1):270.
- Normand C, Thieulent CJ, Fortier C, Sutton G, Senamaud-Beaufort C, Jourdren L, Blugeon C, Vidalain PO, Pronost S, Hue ES. A Screening Study Identified Decitabine as an Inhibitor of Equid Herpesvirus 4 That Enhances the Innate Antiviral Response. Viruses 2024 May 8;16(5).
- Lunn DP, Burgess BA, Dorman DC, Goehring LS, Gross P, Osterrieder K, Pusterla N, Soboll Hussey G. Updated ACVIM consensus statement on equine herpesvirus-1. J Vet Intern Med 2024 May-Jun;38(3):1290-1299.
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