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Veterinary microbiology2009; 141(1-2); 5-11; doi: 10.1016/j.vetmic.2009.07.030

The increased prevalence of neuropathogenic strains of EHV-1 in equine abortions.

Abstract: A panel of 426 archived EHV-1 isolates collected (1951-2006) from equine abortions was analyzed using a real-time Taq-Man((R)) allelic discrimination PCR assay. Based on previous findings, isolates possessing adenine at nucleotide position 2254 (A(2254)) in ORF30 were classified as having a non-neuropathogenic genotype and those with guanine at 2254 (G(2254)) were designated as the neuropathogenic genotype. The resultant data demonstrated that viruses with the neuropathogenic genotype existed in the 1950s and isolates with this genotype increased from 3.3% in the 1960s to 14.4% in the 1990s. The incidence of EHV-1 isolates from 2000 to 2006 with G at position 2254 is 19.4%, suggesting that viruses with the neuropathogenic genotype are continuing to increase in prevalence within the latent reservoir of the virus, leading to greater risks for costly outbreaks of equine herpesvirus neurologic disease. Another highly significant finding was two isolates failed to react with either probe in the allelic discrimination assay. These isolates were found to possess an adenine to cytosine substitution at position 2258 (A(2258)-->C(2258)) in ORF30, in addition to A(2254)-->G(2254). Interestingly, the non-neuropathogenic RAC-H modified live vaccine strain of EHV-1 also contains both A(2254)-->G(2254) and A(2258)-->C(2258) substitutions. This finding clearly suggests that additional research is required before the genetic basis of the neuropathogenic phenotype in EHV-1 is fully understood.
Published by Elsevier B.V.
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Publication Date: 2009-08-08 PubMed ID: 19733451DOI: 10.1016/j.vetmic.2009.07.030Google Scholar: Lookup
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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.

The research examines an increase of neuropathogenic strains of EHV-1 (Equine Herpesvirus 1) found in equine abortions, over a period from 1951-2006, demonstrated through a PCR assay. The increase in neuropathogenic genotype among these viruses highlights an increased risk for outbreaks of equine herpesvirus neurological disease.

Methodology

  • The research team studied a collection of 426 archived EHV-1 isolates. These were obtained from equine abortions from 1951-2006.
  • The isolates were analyzed using a real-time Taq-Man® allelic discrimination PCR assay to determine their genotypes.
  • The genotype was determined by observing nucleotide position 2254 in ORF30 in each isolate.
  • If adenine was present at the position, the isolate was deemed to have a non-neuropathogenic genotype. If guanine was present, the isolate was classified as having a neuropathogenic genotype.

Findings

  • Data revealed that the neuropathogenic genotype of the virus was present as early as the 1950s.
  • The incidence of isolates with the neuropathogenic genotype increased from 3.3% in the 1960s to 14.4% in the 1990s.
  • Further, between 2000 and 2006, the incidence of EHV-1 isolates with guanine at position 2254 increased to 19.4%.
  • This continual increase in the presence of the neuropathogenic genotype suggests that this variant of the virus is growing within its latent reservoir, presenting an escalated risk of outbreaks of equine herpesvirus neurologic disease.

Additional Significant Findings

  • Two of the studied isolates did not react with either probe in the allelic discrimination assay. These particular isolates had a substitution of adenine to cytosine at position 2258 (A2258–>C2258), in addition to A2254–>G2254.
  • Interestingly, the non-neuropathogenic RAC-H modified live vaccine strain of EHV-1 also contained both these substitutions.

Implications of Findings

  • The presence of the adenine to cytosine substitution at position 2258 (A2258–>C2258) along with A2254–>G2254 in some of the tested strains suggests that our understanding of the neuropathogenic genotype might need to be revised.
  • The researchers suggest that there needs to be more intensive study into the genetic basis of the neuropathogenic phenotype in EHV-1, to fully understand its interactions and effects.

Cite This Article

APA
Smith KL, Allen GP, Branscum AJ, Frank Cook R, Vickers ML, Timoney PJ, Balasuriya UB. (2009). The increased prevalence of neuropathogenic strains of EHV-1 in equine abortions. Vet Microbiol, 141(1-2), 5-11. https://doi.org/10.1016/j.vetmic.2009.07.030

Publication

Veterinary microbiology
ISSN: 1873-2542
NlmUniqueID: 7705469
Country: Netherlands
Language: English
Volume: 141
Issue: 1-2
Pages: 5-11

Researcher Affiliations

Smith, Kathryn L
  • 108 Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY 40546, USA.
Allen, George P
    Branscum, Adam J
      Frank Cook, R
        Vickers, Mary L
          Timoney, Peter J
            Balasuriya, Udeni B R

              MeSH Terms

              • Abortion, Veterinary / epidemiology
              • Abortion, Veterinary / virology
              • Animals
              • DNA, Viral / genetics
              • Herpesvirus 1, Equid / genetics
              • Herpesvirus 1, Equid / isolation & purification
              • Horse Diseases / epidemiology
              • Horse Diseases / virology
              • Horses
              • Nervous System Diseases / epidemiology
              • Nervous System Diseases / veterinary
              • Nervous System Diseases / virology
              • Polymerase Chain Reaction
              • Prevalence

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