FREE SHIPPING over $40
OVER 9000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Home / Equine Research Bank / Viruses / First Molecular Evidence of Equine Herpesvirus Type 1 (EHV-1...
Viruses2025; 17(6); 862; doi: 10.3390/v17060862

First Molecular Evidence of Equine Herpesvirus Type 1 (EHV-1) in Ocular Swabs of Clinically Affected Horses.

Abstract: Equine Herpesvirus Type 1 (EHV-1) is a significant pathogen within the subfamily, causing respiratory disease, abortions, and, in severe cases, equine herpesvirus myeloencephalopathy (EHM). While nasal swabs and blood samples are commonly used for real-time polymerase chain reaction (RT-PCR) diagnosis, variability in viral shedding necessitates exploring additional sample types. This study reports the first molecular detection of EHV-1 in ocular swabs from naturally infected horses during an outbreak in the Valencian Community in 2023. Nasal and ocular swabs were collected from ten symptomatic horses and analyzed via RT-PCR. EHV-1 was detected in all cases, with higher viral loads in nasal samples. Although nasal swabs remain the most reliable sample for EHV-1 detection, the presence of viral DNA in tear fluid suggests a previously unrecognized route of viral shedding. These findings support further investigation into the role of ocular secretions in the pathogenesis and epidemiology of EHV-1. Additional studies are needed to determine the clinical relevance and potential utility of ocular swabs in specific outbreak scenarios.
Get Full Text
Publication Date: 2025-06-18 PubMed ID: 40573453PubMed Central: PMC12197432DOI: 10.3390/v17060862Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This research article presents the first molecular detection of Equine Herpesvirus Type 1 (EHV-1) in ocular swabs from horses showing clinical symptoms during an outbreak.
  • The study emphasizes the importance of exploring ocular secretions as a potential new sample type for detecting EHV-1, which traditionally uses nasal swabs and blood samples.

Background on Equine Herpesvirus Type 1 (EHV-1)

  • EHV-1 is a virus within the Herpesviridae subfamily that affects horses and can cause a range of health issues including:
    • Respiratory disease
    • Abortions in pregnant mares
    • Equine Herpesvirus Myeloencephalopathy (EHM), a severe neurological disorder
  • Common diagnostic practices for EHV-1 infection involve collecting nasal swabs or blood samples to detect the virus using real-time polymerase chain reaction (RT-PCR).
  • Despite being standard, variability in viral shedding through these common sample types poses challenges in consistent virus detection.

Aim and Significance of the Study

  • The study aimed to investigate whether ocular swabs (samples collected from the surface of the eye) could be used to detect EHV-1 DNA.
  • This is significant because it could reveal a new route of virus shedding and expand diagnostic methods, particularly since ocular secretions have not been previously considered a source for molecular evidence of the virus.

Methods

  • The researchers collected both nasal and ocular swabs from ten horses exhibiting clinical signs consistent with EHV-1 infection during a natural outbreak in the Valencian Community in 2023.
  • All samples underwent RT-PCR testing, a molecular technique that amplifies viral genetic material to confirm the presence of EHV-1.

Findings

  • EHV-1 viral DNA was detected in every sampled horse, confirming active infection in the study population.
  • The viral load, which indicates the amount of virus present, was consistently higher in nasal swabs compared to ocular swabs.
  • Despite lower viral loads, the presence of EHV-1 DNA in ocular swabs demonstrates that the virus can also be shed in tear fluid, a novel discovery.

Implications and Future Directions

  • This discovery suggests the eye may serve as an additional reservoir or shedding route for EHV-1, which has implications for understanding the pathogenesis—the development and progression—of the disease.
  • Ocular swabs could potentially augment diagnostic practices, especially in settings where nasal swabbing is challenging or in early detection contexts.
  • Additional research is necessary to:
    • Determine how frequently ocular shedding occurs across various outbreak situations.
    • Assess whether ocular shedding influences transmission dynamics of EHV-1 between horses.
    • Explore the clinical significance of detecting EHV-1 in tear fluid, particularly if viral shedding there correlates with specific symptoms or disease severity.

Conclusion

  • The study provides the first molecular evidence of EHV-1 presence in ocular secretions, expanding the understanding of viral shedding beyond traditional respiratory and blood samples.
  • Though nasal swabs remain the most reliable for diagnostic detection, ocular swabs represent a promising complementary tool for research and potentially diagnosis in equine herpesvirus outbreaks.

Cite This Article

APA
Musoles-Cuenca B, Padilla-Blanco M, Vitale V, Lorenzo-Bermejo T, de la Cuesta-Torrado M, Ballester B, Maiques E, Rubio-Guerri C, Velloso Alvarez A. (2025). First Molecular Evidence of Equine Herpesvirus Type 1 (EHV-1) in Ocular Swabs of Clinically Affected Horses. Viruses, 17(6), 862. https://doi.org/10.3390/v17060862

Publication

Viruses
ISSN: 1999-4915
NlmUniqueID: 101509722
Country: Switzerland
Language: English
Volume: 17
Issue: 6
PII: 862

Researcher Affiliations

Musoles-Cuenca, Beatriz
  • Department of Biomedical Sciences, Faculty of Health Sciences, Universidad Cardenal Herrera-CEU, CEU Universities, 46115 Valencia, Spain.
Padilla-Blanco, Miguel
  • Department of Pharmacy, Faculty of Health Sciences, Universidad Cardenal Herrera-CEU, CEU Universities, 46115 Valencia, Spain.
  • Viral Immunology Laboratory, Molecular Biomedicine Department, Margarita Salas Center for Biological Research (CIB-CSIC), 28040 Madrid, Spain.
Vitale, Valentina
  • Department of Animal Medicine and Surgery, University Cardenal Herrera-CEU, CEU Universities, 46115 Valencia, Spain.
Lorenzo-Bermejo, Teresa
  • Department of Biomedical Sciences, Faculty of Health Sciences, Universidad Cardenal Herrera-CEU, CEU Universities, 46115 Valencia, Spain.
de la Cuesta-Torrado, María
  • Department of Animal Medicine and Surgery, University Cardenal Herrera-CEU, CEU Universities, 46115 Valencia, Spain.
Ballester, Beatriz
  • Department of Biomedical Sciences, Faculty of Health Sciences, Universidad Cardenal Herrera-CEU, CEU Universities, 46115 Valencia, Spain.
Maiques, Elisa
  • Department of Biomedical Sciences, Faculty of Health Sciences, Universidad Cardenal Herrera-CEU, CEU Universities, 46115 Valencia, Spain.
Rubio-Guerri, Consuelo
  • Department of Pharmacy, Faculty of Health Sciences, Universidad Cardenal Herrera-CEU, CEU Universities, 46115 Valencia, Spain.
Velloso Alvarez, Ana
  • Department of Animal Medicine and Surgery, University Cardenal Herrera-CEU, CEU Universities, 46115 Valencia, Spain.

MeSH Terms

  • Animals
  • Horses
  • Herpesvirus 1, Equid / genetics
  • Herpesvirus 1, Equid / isolation & purification
  • Horse Diseases / virology
  • Horse Diseases / epidemiology
  • Horse Diseases / diagnosis
  • Herpesviridae Infections / veterinary
  • Herpesviridae Infections / virology
  • Herpesviridae Infections / epidemiology
  • Herpesviridae Infections / diagnosis
  • Disease Outbreaks / veterinary
  • Eye / virology
  • Virus Shedding
  • DNA, Viral / genetics
  • Viral Load

Conflict of Interest Statement

The authors declare no conflicts of interest.

References

This article includes 35 references
  1. Pusterla N., Lawton K., Barnum S., Ross K., Purcell K. Investigation of an Outbreak of Equine Herpesvirus-1 Myeloencephalopathy in a Population of Aged Working Equids. Viruses. 2024;16:1693. doi: 10.3390/v16121963.
    doi: 10.3390/v16121963pmc: PMC11728824pubmed: 39772269google scholar: lookup
  2. Couroucé A., Normand C., Tessier C., Pomares R., Thévenot J., Marcillaud-Pitel C., Legrand L., Pitel P.-H., Pronost S., Lupo C. Equine Herpesvirus-1 Outbreak During a Show-Jumping Competition: A Clinical and Epidemiological Study. J. Equine Vet. Sci. 2023;128:104869. doi: 10.1016/j.jevs.2023.104869.
    doi: 10.1016/j.jevs.2023.104869pubmed: 37339699google scholar: lookup
  3. Davison A.J., Eberle R., Ehlers B., Hayward G.S., McGeoch D.J., Minson A.C., Pellett P.E., Roizman B., Studdert M.J., Thiry E. The order Herpesvirales. Arch. Virol. 2009;154:171–177. doi: 10.1007/s00705-008-0278-4.
    doi: 10.1007/s00705-008-0278-4pmc: PMC3552636pubmed: 19066710google scholar: lookup
  4. Laval K., Poelaert K.C.K., Van Cleemput J., Zhao J., Vandekerckhove A.P., Gryspeerdt A.C., Garré B., van der Meulen K., Baghi H.B., Dubale H.N., et al. The Pathogenesis and Immune Evasive Mechanisms of Equine Herpesvirus Type 1. Front. Microbiol. 2021;12:662686. doi: 10.3389/fmicb.2021.662686.
    doi: 10.3389/fmicb.2021.662686pmc: PMC7970122pubmed: 33746936google scholar: lookup
  5. Roizmann B., Desrosiers R.C., Fleckenstein B., Lopez C., Minson A.C., Studdert M.J. The Family Herpesviridae: An Update. Arch. Virol. 1992;123:425–449. doi: 10.1007/BF01317276.
    doi: 10.1007/BF01317276pubmed: 1562239google scholar: lookup
  6. Pusterla N., Hussey G.S. Equine Herpesvirus 1 Myeloencephalopathy. Vet. Clin. N. Am. Equine Pract. 2014;30:489–506. doi: 10.1016/j.cveq.2014.08.006.
    doi: 10.1016/j.cveq.2014.08.006pubmed: 25300635google scholar: lookup
  7. Hussey G.S. Key Determinants in the Pathogenesis of Equine Herpesvirus 1 and 4 Infections. Vet. Pathol. 2019;56:656–659. doi: 10.1177/0300985819849498.
    doi: 10.1177/0300985819849498pubmed: 31394999google scholar: lookup
  8. Khusro A., Aarti C., Rivas-Caceres R.R., Barbabosa-Pliego A. Equine Herpesvirus-I Infection in Horses: Recent Updates on Its Pathogenicity, Vaccination, and Preventive Management Strategies. J. Equine Vet. Sci. 2020;87:102923. doi: 10.1016/j.jevs.2020.102923.
    doi: 10.1016/j.jevs.2020.102923pubmed: 32172913google scholar: lookup
  9. Allen G.P., Kydd J.H., Slater J.D., Smith K.C. Equid Herpesvirus-1 (EHV-1) and -4 (EHV-4) Infections. In: Coetzer J.A.W., Tustin R.C., editors. Infectious Diseases of Livestock. 2nd ed. Oxford Press; Cape Town, South Africa: 2004. pp. 829–859.
  10. Gonzalez-Medina S., Newton J.R. Equine Herpesvirus-1: Dealing Practically but Effectively with an Ever Present Threat. Equine Vet. J. 2015;47:142–144. doi: 10.1111/evj.12416.
    doi: 10.1111/evj.12416pubmed: 25644768google scholar: lookup
  11. Del Piero F., Wilkins P.A. Pulmonary vasculotropic EHV-1 infection in equids. Vet. Pathol. 2001;38:474. doi: 10.1354/vp.38-4-474.
    doi: 10.1354/vp.38-4-474pubmed: 11467487google scholar: lookup
  12. Hussey G.S., Goehring L.S., Lunn D.P., Hussey S.B., Huang T., Osterrieder N., Powell C., Hand J., Holz C., Slater J. Experimental infection with equine herpesvirus type 1 (EHV-1) induces chorioretinal lesions. Vet. Res. 2013;44:118. doi: 10.1186/1297-9716-44-118.
    doi: 10.1186/1297-9716-44-118pmc: PMC4028784pubmed: 24308772google scholar: lookup
  13. McCartan C.G., Russel M.M., Wood J.L.N., Mumford J.A. Clinical, serological and virological characteristics of an outbreak of paresis and neonatal foal disease due to equine herpesvirus-1 on a stud farm. Vet. Rec. 1995;136:7–12. doi: 10.1136/vr.136.1.7.
    doi: 10.1136/vr.136.1.7pubmed: 7900264google scholar: lookup
  14. de la Cuesta-Torrado M., Velloso Alvarez A., Neira-Egea P., Cuervo-Arango J. Long-term performance of show-jumping horses and relationship with severity of ataxia and complications associated with myeloencephalopathy caused by equine herpesvirus-1. J. Vet. Intern. Med. 2024;38:1799–1807. doi: 10.1111/jvim.17070.
    doi: 10.1111/jvim.17070pmc: PMC11099729pubmed: 38609161google scholar: lookup
  15. Patel J.R., Heldens J. Equine Herpesviruses 1 (EHV-1) and 4 (EHV-4)—Epidemiology, Disease and Immunoprophylaxis: A Brief Review. Vet. J. 2005;170:14–23. doi: 10.1016/j.tvjl.2004.04.018.
    doi: 10.1016/j.tvjl.2004.04.018pubmed: 15993786google scholar: lookup
  16. Velloso-Alvarez A., Jose-Cunilleras E., Dorrego-Rodriguez A., Santiago-Llorente I., de la Cuesta-Torrado M., Troya-Portillo L., Rivera B., Vitale V., de Juan L., Cruz-Lopez F. Detection of equine herpesvirus-1 (EHV-1) in urine samples during outbreaks of equine herpesvirus myeloencephalopathy. Equine Vet. J. 2024;56:456–463. doi: 10.1111/evj.14007.
    doi: 10.1111/evj.14007pubmed: 37699794google scholar: lookup
  17. Hussey S.B., Clark R., Lunn K.F., Breathnach C., Soboll G., Whalley J.M., Lunn D.P. Detection and Quantification of Equine Herpesvirus-1 Viremia and Nasal Shedding by Real-Time Polymerase Chain Reaction. J. Vet. Diagn. Investig. 2006;18:335–342. doi: 10.1177/104063870601800403.
    doi: 10.1177/104063870601800403pubmed: 16921871google scholar: lookup
  18. Pusterla N., Barnum S., Young A., Mendonsa E., Lee S., Hankin S., Brittner S., Finno C.J. Molecular Monitoring of EHV-1 in Silently Infected Performance Horses through Nasal and Environmental Sample Testing. Pathogens. 2022;11:720. doi: 10.3390/pathogens11070720.
    doi: 10.3390/pathogens11070720pmc: PMC9317758pubmed: 35889966google scholar: lookup
  19. Paillot R., Prowse L., Montesso F., Stewart B., Jordon L., Newton J.R. Duration of equine influenza virus shedding and infectivity in immunised horses after experimental infection with EIV A/eq2/Richmond/1/07. Vet. Microbiol. 2013;166:22–34. doi: 10.1016/j.vetmic.2013.04.027.
    doi: 10.1016/j.vetmic.2013.04.027pubmed: 23769636google scholar: lookup
  20. Vandenberghe E., Boshuizen B., Delesalle C.J.G., Goehring L.S., Groome K.A., van Maanen K., de Bruijn C.M. New insights into the management of an EHV-1 (Equine Hospital) outbreak. Viruses. 2021;13:1429. doi: 10.3390/v13081429.
    doi: 10.3390/v13081429pmc: PMC8402800pubmed: 34452295google scholar: lookup
  21. Pusterla N., Wilson W.D., Mapes S., Finno C., Isbell D., Arthur R.M., Ferraro G.L. Characterization of viral loads, strain and state of equine herpesvirus-1 using real-time PCR in horses following natural exposure at a racetrack in California. Vet. J. 2009;179:230–239. doi: 10.1016/j.tvjl.2007.09.018.
    doi: 10.1016/j.tvjl.2007.09.018pubmed: 18024200google scholar: lookup
  22. Pusterla N., Mapes S., Wilson W.D. Use of viral loads in blood and nasopharyngeal secretions for the diagnosis of EHV-1 infection in field cases. Vet. Rec. 2008;162:728–729. doi: 10.1136/vr.162.22.728.
    doi: 10.1136/vr.162.22.728pubmed: 18515763google scholar: lookup
  23. Pusterla N., Mapes S., Wademan C., White A., Estell K., Swain E. Investigation of the Role of Mules as Silent Shedders of EHV-1 during an Outbreak of EHV-1 Myeloencephalopathy in California. Vet. Rec. 2012;170:465. doi: 10.1136/vr.100598.
    doi: 10.1136/vr.100598pubmed: 22472540google scholar: lookup
  24. Sonis J.M., Goehring L.S. Nasal Shedding of Equid Herpesvirus Type 1 and Type 4 in Hospitalized, Febrile Horses. J. Equine Vet. Sci. 2013;33:756–759. doi: 10.1016/j.jevs.2012.11.002.
    doi: 10.1016/j.jevs.2012.11.002google scholar: lookup
  25. Wilcox A., Barnum S., Wademan C., Corbin R., Escobar E., Hodzic E., Schumacher S., Pusterla N. Frequency of Detection of Respiratory Pathogens in Clinically Healthy Show Horses Following a Multi-County Outbreak of Equine Herpesvirus-1 Myeloencephalopathy in California. Pathogens. 2022;11:1161. doi: 10.3390/pathogens11101161.
    doi: 10.3390/pathogens11101161pmc: PMC9612363pubmed: 36297218google scholar: lookup
  26. Pusterla N., Barnum S., Miller J., Varnell S., Dallap-Schaer B., Aceto H., Simeone A. Investigation of an EHV-1 Outbreak in the United States Caused by a New H752 Genotype. Pathogens. 2021;10:747. doi: 10.3390/pathogens10060747.
    doi: 10.3390/pathogens10060747pmc: PMC8231618pubmed: 34199153google scholar: lookup
  27. Price D., Barnum S., Mize J., Pusterla N. Investigation of the Use of Non-Invasive Samples for the Molecular Detection of EHV-1 in Horses with and without Clinical Infection. Pathogens. 2022;11:574. doi: 10.3390/pathogens11050574.
    doi: 10.3390/pathogens11050574pmc: PMC9144909pubmed: 35631095google scholar: lookup
  28. Mayhew I.G., Graham M., Waller H. Congenital occipitoatlantoaxial malformations in the horse. Vet. Rec. 1978;103:125–128. doi: 10.1111/j.2042-3306.1978.tb02232.x.
    doi: 10.1111/j.2042-3306.1978.tb02232.xpubmed: 565704google scholar: lookup
  29. Vereecke N., Carnet F., Pronost S., Vanschandevijl K., Theuns S., Nauwynck H. Genome Sequences of Equine Herpesvirus 1 Strains from a European Outbreak of Neurological Disorders Linked to a Horse Gathering in Valencia, Spain, in 2021. Microbiol. Resour. Announc. 2021;10:e00333-21. doi: 10.1128/MRA.00333-21.
    doi: 10.1128/MRA.00333-21pmc: PMC8188346pubmed: 34016681google scholar: lookup
  30. Graham D.A. Bovine herpes virus-1 (BoHV-1) in cattle-a review with emphasis on reproductive impacts and the emergence of infection in Ireland and the United Kingdom. Ir. Vet. J. 2013;66:15. doi: 10.1186/2046-0481-66-15.
    doi: 10.1186/2046-0481-66-15pmc: PMC3750245pubmed: 23916092google scholar: lookup
  31. Lee Y., Maes R.K., Kruger J.M., Kiupel M., Giessler K.S., Soboll Hussey G. Safety and Efficacy of Felid Herpesvirus-1 Deletion Mutants in Cats. Viruses. 2021;13:163. doi: 10.3390/v13020163.
    doi: 10.3390/v13020163pmc: PMC7911815pubmed: 33499363google scholar: lookup
  32. Ledbetter E.C., da Silva E.C., Kim S.G., Dubovi E.J., Schwark W.S. Frequency of spontaneous canine herpesvirus-1 reactivation and ocular viral shedding in latently infected dogs and canine herpesvirus-1 reactivation and ocular viral shedding induced by topical administration of cyclosporine and systemic administration of corticosteroids. Am. J. Vet. Res. 2012;73:1079–1084. doi: 10.2460/ajvr.73.7.1079.
    doi: 10.2460/ajvr.73.7.1079pubmed: 22738061google scholar: lookup
  33. Goehring L.S., van Maanen C., Berendsen M., Cullinane A., de Groot R.J., Rottier P.J.M., Wesselingh J.J.C.M., van Oldruitenborh-Oosterbaan M.M.S. Experimental infection with neuropathogenic equid herpesvirus type 1 (EHV-1) in adult horses. Vet. J. 2010;186:180–187. doi: 10.1016/j.tvjl.2009.08.007.
    doi: 10.1016/j.tvjl.2009.08.007pubmed: 19726209google scholar: lookup
  34. Petano-Duque J.M., Urueña-Martinez E., Cabezas-Callejas L.L., Perilla-Amaya J., Rueda-García V., Rondón-Barragán I.S., Lopera-Vásquez R. Molecular and serological investigation of equine herpesvirus type 1 (EHV-1) and type 4 (EHV-4) in horses in Ibagué, Tolima. Vet. Med. Int. 2025;2025:1661949. doi: 10.1155/vmi/1661949.
    doi: 10.1155/vmi/1661949pmc: PMC11824386pubmed: 39949613google scholar: lookup
  35. Seeber P.A., Dayaram A., Sicks F., Osterrieder N., Franz M., Greenwood A.D. Noninvasive Detection of Equid Herpesviruses in Fecal Samples. Appl. Environ. Microbiol. 2019;85:e02234-18. doi: 10.1128/AEM.02234-18.
    doi: 10.1128/AEM.02234-18pmc: PMC6344631pubmed: 30446563google scholar: lookup

Citations

This article has been cited 0 times.
Subscribe to our newsletter
Join 99,002 horse owners like you who receive our email updates on horse health and nutrition.