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Home / Equine Research Bank / Med Vet Entomol / Vector competence of Culicoides species and the seroprevalen...
Medical and veterinary entomology2005; 18(4); 398-407; doi: 10.1111/j.0269-283X.2004.00524.x

Vector competence of Culicoides species and the seroprevalence of homologous neutralizing antibody in horses for six serotypes of equine encephalosis virus (EEV) in South Africa.

Abstract: Field-collected Culicoides species (Diptera: Ceratopogonidae) were fed on horse blood-virus mixtures containing one of the six serotypes of equine encephalosis virus (EEV1 to EEV6). The virus mean titres in the bloodmeals varied between 6.1 and 7.0 log10TCID50/mL. Of 19 Culicoides species assayed after 10 days extrinsic incubation at 23.5 degrees C, five yielded the challenge virus, namely Culicoides (Avaritia) imicola Kieffer (EEV1-6), C. (A.) bolitinos Meiswinkel (EEV1, 2, 4, 6), C. (Meijerehelea) leucostictus Kiefer (EEV1, 2), C. (Culicoides) magnus Colaço (EEV1) and C. (Hoffmania) zuluensis de Meillon (EEV2). Virus recovery rates ranged from 0.5 to 13%. The mean levels of viral replication differed between serotypes and Culicoides species and ranged from 1.0 to 2.3 log10TCID50/midge. Culicoides midges shown in this study to be susceptible to oral infection with EEV are widely distributed in South Africa but differ considerably in their abundance, host preference and breeding sites. Of 1456 horses tested, 1144 (77%) had antibody to EEV. Homologous virus-neutralizing antibodies to all six serotypes were detected in individual horses from all eight geographical provinces of South Africa. The distribution, prevalence, and the rate of exposure to individual serotypes varied significantly between regions. The potential for vectoring of EEV in the field by several Culicoides species with unique ecologies and lack of cross-protection to re-infection with multiple serotypes highlights some of the mechanisms that are likely to play a role in the virus' natural maintenance cycle and the highly efficient level of countrywide transmission amongst South African horses.
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Publication Date: 2005-01-12 PubMed ID: 15642007DOI: 10.1111/j.0269-283X.2004.00524.xGoogle Scholar: Lookup
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  • 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.

The research paper is a study on the ability of various species of Culicoides to transmit six identified serotypes of equine encephalosis virus (EEV) in South Africa, and the prevalence of antibodies against these viruses in the horse population.

Experiment Approach

  • The group of researchers collected various Culicoides species, which are small biting flies known to transmit diseases to animals.
  • The collected species were fed with a mixture of horse blood and one of the six serotypes of equine encephalosis virus (EEV1 to EEV6).
  • The virus mean titres (viral concentrations) in the blood meals were regulated to vary between 6.1 and 7.0 log10TCID50/mL.
  • After an extrinsic incubation period of 10 days at 23.5 degrees C, 19 Culicoides species were assayed to see if they yielded the virus used in the feeding process.

Experiment Results

  • Out of 19 species, five were found to carry the challenge virus, with virus recovery rates from the midges ranging from 0.5% to 13%.
  • The five virus carrying Culicoides species were C. (Avaritia) imicola Kieffer (EEV1-6), C. (A.) bolitinos Meiswinkel (EEV1, 2, 4, 6), C. (Meijerehelea) leucostictus Kiefer (EEV1, 2), C. (Culicoides) magnus Colaço (EEV1) and C. (Hoffmania) zuluensis de Meillon (EEV2).
  • The mean levels of viral replication differed between serotypes and Culicoides species, ranging from 1.0 to 2.3 log10TCID50/midge.
  • The results showed these Culicoides midges to be vulnerable to oral infection with EEV are widely distributed in South Africa and they differed considerably in their numbers, host preference and breeding sites.

Seroprevalence Study

  • Besides, the researchers also tested 1456 horses in South Africa, out of which about 77% had antibodies against the virus, indicating a past infection.
  • These antibodies neutralized all six serotypes and were found in horses across all eight geographical regions of the country, although their distribution, prevalence, and exposure rates varied significantly across regions.
  • These results clearly indicate that equine encephalosis virus infection is common among horses in South Africa.

Study Implications

  • The study identified multiple Culicoides species that possess the ability to transmit EEV, each with unique ecological traits influencing their vectoring potential.
  • The widespread prevalence of these species and the high seroprevalence rate in horses signify a high potential for the virus to maintain its cycle in nature and transmit efficiently amongst the horse population.
  • The research also highlights the lack of cross-protection in horses against re-infection with multiple serotypes, reflecting a complex landscape for disease control.

Cite This Article

APA
Paweska JT, Venter GJ. (2005). Vector competence of Culicoides species and the seroprevalence of homologous neutralizing antibody in horses for six serotypes of equine encephalosis virus (EEV) in South Africa. Med Vet Entomol, 18(4), 398-407. https://doi.org/10.1111/j.0269-283X.2004.00524.x

Publication

Medical and veterinary entomology
ISSN: 0269-283X
NlmUniqueID: 8708682
Country: England
Language: English
Volume: 18
Issue: 4
Pages: 398-407

Researcher Affiliations

Paweska, J T
  • ARC-Onderstepoort Veterinary Institute, Onderstepoort, South Africa. januszp@nicd.ac.za
Venter, G J

    MeSH Terms

    • Animals
    • Antibodies, Viral / blood
    • Ceratopogonidae / virology
    • Horse Diseases / epidemiology
    • Horse Diseases / immunology
    • Horses
    • Insect Vectors / virology
    • Orbivirus / immunology
    • Reoviridae Infections / veterinary
    • Seroepidemiologic Studies
    • South Africa / epidemiology
    • Species Specificity

    Citations

    This article has been cited 10 times.
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