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Viruses2021; 13(3); doi: 10.3390/v13030398

Epidemiology and Genomic Analysis of Equine Encephalosis Virus Detected in Horses with Clinical Signs in South Africa, 2010-2017.

Abstract: Equine encephalosis virus (EEV) is a neglected virus endemic to South Africa and is considered to generally result in mild disease in equines. Specimens were analyzed from live horses that presented with undefined neurological, febrile, or respiratory signs, or sudden and unexpected death. Between 2010 and 2017, 111 of 1523 (7.3%) horse samples tested positive for EEV using a nested real-time reverse transcriptase polymerase chain reaction (rRT-PCR). Clinical signs were reported in 106 (7.2%) EEV positive and 1360 negative horses and included pyrexia (77/106, 72.6%), icterus (20/106, 18.9%) and dyspnea (12/106, 11.3%). Neurological signs were inversely associated with EEV infection (OR < 1, p < 0.05) relative to EEV negative cases despite a high percentage of animals presenting with neurological abnormalities (51/106, 48.1%). Seventeen of the EEV positive horses also had coinfections with either West Nile (5/106, 4.7%), Middelburg (4/106, 3.8%) or African Horse sickness virus (8/106, 7.6%). To investigate a possible genetic link between EEV strains causing the observed clinical signs in horses, the full genomes of six isolates were compared to the reference strains. Based on the outer capsid protein (VP2), serotype 1 and 4 were identified as the predominant serotypes with widespread reassortment between the seven different serotypes.
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Publication Date: 2021-03-02 PubMed ID: 33801457PubMed Central: PMC8001977DOI: 10.3390/v13030398Google 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.

This research focuses on the spread and genomic features of Equine Encephalosis Virus in South Africa between 2010 and 2017. The virus, typically causing mild symptoms in horses, has been found in a substantial number of symptomatic horses, leading to an analysis of the viral strains and their potential impact on the animals’ health.

Research Context and Methodology

  • The study analysed Equine Encephalosis Virus (EEV), a virus endemic to South Africa that primarily affects horses. Even though EEV generally causes mild disease, the study looked at horses presenting more severe symptoms like unexplained neurological, febrile, or respiratory signs, or sudden death.
  • From 2010 to 2017, the researchers collected and examined samples from live horses. They used a nested real-time reverse transcriptase polymerase chain reaction (rRT-PCR) to test for EEV.

Key Findings

  • Of the 1523 horse samples, 111 (7.3%) tested positive for EEV. 106 EEV-positive and 1360 EEV-negative horses displayed clinical symptoms. The prevalent symptoms among EEV-positive horses were fever (in 72.6%), icterus or jaundice (18.9%), and dyspnea or difficulty in breathing (11.3%).
  • Despite nearly half of the EEV-positive horses presenting signs of neurological disorders, an inverse association was found between neurological signs and EEV infection, meaning the instances of neurological signs were lesser in EEV-positive horses compared to EEV-negative ones.
  • A significant number of EEV-positive horses also had coinfections with other viruses like West Nile virus, Middelburg virus, and African Horse sickness virus.
  • The researchers compared the full genomes of six isolates with the reference EEV strains to try to identify a possible genetic link between the strains of EEV causing severe symptoms. The outer capsid protein (VP2) of the virus revealed serotype 1 and 4 as the predominant serotypes (distinct variations within a species), pointing to widespread genetic reassortment across the seven known serotypes of EEV.

Cite This Article

APA
Snyman J, Koekemoer O, van Schalkwyk A, Jansen van Vuren P, Snyman L, Williams J, Venter M. (2021). Epidemiology and Genomic Analysis of Equine Encephalosis Virus Detected in Horses with Clinical Signs in South Africa, 2010-2017. Viruses, 13(3). https://doi.org/10.3390/v13030398

Publication

Viruses
ISSN: 1999-4915
NlmUniqueID: 101509722
Country: Switzerland
Language: English
Volume: 13
Issue: 3

Researcher Affiliations

Snyman, Jumari
  • Centre for Viral Zoonoses, Department Medical Virology, University of Pretoria, Pretoria 0001, South Africa.
Koekemoer, Otto
  • Agricultural Research Council, Onderstepoort Veterinary Research, Onderstepoort 0110, South Africa.
van Schalkwyk, Antoinette
  • Agricultural Research Council, Onderstepoort Veterinary Research, Onderstepoort 0110, South Africa.
Jansen van Vuren, Petrus
  • Centre for Viral Zoonoses, Department Medical Virology, University of Pretoria, Pretoria 0001, South Africa.
  • National Health Laboratory Service, Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg 2131, South Africa.
Snyman, Louwtjie
  • Faculty of Veterinary Science, Department Veterinary Tropical Disease, University of Pretoria, Onderstepoort 0110, South Africa.
Williams, June
  • Department of Paraclinical Science, Section Pathology, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa.
Venter, Marietjie
  • Centre for Viral Zoonoses, Department Medical Virology, University of Pretoria, Pretoria 0001, South Africa.

MeSH Terms

  • Animals
  • Genome, Viral
  • Horse Diseases / epidemiology
  • Horse Diseases / virology
  • Horses
  • Orbivirus / genetics
  • Prevalence
  • Reoviridae Infections / epidemiology
  • Reoviridae Infections / veterinary
  • Serogroup
  • South Africa / epidemiology

Conflict of Interest Statement

The authors declare no conflict of interest.

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Citations

This article has been cited 5 times.
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