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Possible over-wintering of bluetongue virus in Culicoides populations in the Onderstepoort area, Gauteng, South Africa

Several studies have demonstrated the ability of certain viruses to overwinter in arthropod vectors. The over-wintering mechanism of bluetongue virus (BTV) is unknown. One hypothesis is over-wintering within adult Culicoides midges (Diptera; Ceratopogonidae) that survive mild winters where temperatu...

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Autores principales: Steyn, Jumari, Venter, Gert J., Labuschagne, Karien, Majatladi, Daphney, Boikanyo, Solomon N.B., Lourens, Carina, Ebersohn, Karen, Venter, Estelle H.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: AOSIS 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6138179/
https://www.ncbi.nlm.nih.gov/pubmed/28155292
http://dx.doi.org/10.4102/jsava.v87i1.1371
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author Steyn, Jumari
Venter, Gert J.
Labuschagne, Karien
Majatladi, Daphney
Boikanyo, Solomon N.B.
Lourens, Carina
Ebersohn, Karen
Venter, Estelle H.
author_facet Steyn, Jumari
Venter, Gert J.
Labuschagne, Karien
Majatladi, Daphney
Boikanyo, Solomon N.B.
Lourens, Carina
Ebersohn, Karen
Venter, Estelle H.
author_sort Steyn, Jumari
collection PubMed
description Several studies have demonstrated the ability of certain viruses to overwinter in arthropod vectors. The over-wintering mechanism of bluetongue virus (BTV) is unknown. One hypothesis is over-wintering within adult Culicoides midges (Diptera; Ceratopogonidae) that survive mild winters where temperatures seldom drop below 10 °C. The reduced activity of midges and the absence of outbreaks during winter may create the impression that the virus has disappeared from an area. Light traps were used in close association with horses to collect Culicoides midges from July 2010 to September 2011 in the Onderstepoort area, in Gauteng Province, South Africa. More than 500 000 Culicoides midges were collected from 88 collections and sorted to species level, revealing 26 different Culicoides species. Culicoides midges were present throughout the 15 month study. Nine Culicoides species potentially capable of transmitting BTV were present during the winter months. Midges were screened for the presence of BTV ribonucleic acid (RNA) with the aid of a real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) assay. In total 91.2% of midge pools tested positive for BTV RNA. PCR results were compared with previous virus isolation results (VI) that demonstrated the presence of viruses in summer and autumn months. The results indicate that BTV-infected Culicoides vectors are present throughout the year in the study area. Viral RNA-positive midges were also found throughout the year with VI positive midge pools only in summer and early autumn. Midges that survive mild winter temperatures could therefore harbour BTV but with a decreased vector capacity. When the population size, biting rate and viral replication decrease, it could stop BTV transmission. Over-wintering of BTV in the Onderstepoort region could therefore result in re-emergence because of increased vector activity rather than reintroduction from outside the region.
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spelling pubmed-61381792018-09-26 Possible over-wintering of bluetongue virus in Culicoides populations in the Onderstepoort area, Gauteng, South Africa Steyn, Jumari Venter, Gert J. Labuschagne, Karien Majatladi, Daphney Boikanyo, Solomon N.B. Lourens, Carina Ebersohn, Karen Venter, Estelle H. J S Afr Vet Assoc Original Research Several studies have demonstrated the ability of certain viruses to overwinter in arthropod vectors. The over-wintering mechanism of bluetongue virus (BTV) is unknown. One hypothesis is over-wintering within adult Culicoides midges (Diptera; Ceratopogonidae) that survive mild winters where temperatures seldom drop below 10 °C. The reduced activity of midges and the absence of outbreaks during winter may create the impression that the virus has disappeared from an area. Light traps were used in close association with horses to collect Culicoides midges from July 2010 to September 2011 in the Onderstepoort area, in Gauteng Province, South Africa. More than 500 000 Culicoides midges were collected from 88 collections and sorted to species level, revealing 26 different Culicoides species. Culicoides midges were present throughout the 15 month study. Nine Culicoides species potentially capable of transmitting BTV were present during the winter months. Midges were screened for the presence of BTV ribonucleic acid (RNA) with the aid of a real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) assay. In total 91.2% of midge pools tested positive for BTV RNA. PCR results were compared with previous virus isolation results (VI) that demonstrated the presence of viruses in summer and autumn months. The results indicate that BTV-infected Culicoides vectors are present throughout the year in the study area. Viral RNA-positive midges were also found throughout the year with VI positive midge pools only in summer and early autumn. Midges that survive mild winter temperatures could therefore harbour BTV but with a decreased vector capacity. When the population size, biting rate and viral replication decrease, it could stop BTV transmission. Over-wintering of BTV in the Onderstepoort region could therefore result in re-emergence because of increased vector activity rather than reintroduction from outside the region. AOSIS 2016-10-31 /pmc/articles/PMC6138179/ /pubmed/28155292 http://dx.doi.org/10.4102/jsava.v87i1.1371 Text en © 2016. The Authors http://creativecommons.org/licenses/by/2.0/ Licensee: AOSIS. This work is licensed under the Creative Commons Attribution License.
spellingShingle Original Research
Steyn, Jumari
Venter, Gert J.
Labuschagne, Karien
Majatladi, Daphney
Boikanyo, Solomon N.B.
Lourens, Carina
Ebersohn, Karen
Venter, Estelle H.
Possible over-wintering of bluetongue virus in Culicoides populations in the Onderstepoort area, Gauteng, South Africa
title Possible over-wintering of bluetongue virus in Culicoides populations in the Onderstepoort area, Gauteng, South Africa
title_full Possible over-wintering of bluetongue virus in Culicoides populations in the Onderstepoort area, Gauteng, South Africa
title_fullStr Possible over-wintering of bluetongue virus in Culicoides populations in the Onderstepoort area, Gauteng, South Africa
title_full_unstemmed Possible over-wintering of bluetongue virus in Culicoides populations in the Onderstepoort area, Gauteng, South Africa
title_short Possible over-wintering of bluetongue virus in Culicoides populations in the Onderstepoort area, Gauteng, South Africa
title_sort possible over-wintering of bluetongue virus in culicoides populations in the onderstepoort area, gauteng, south africa
topic Original Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6138179/
https://www.ncbi.nlm.nih.gov/pubmed/28155292
http://dx.doi.org/10.4102/jsava.v87i1.1371
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