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Culicoids as vectors of Schmallenberg virus.

Rasmussen LD, Kristensen B, Kirkeby C, Rasmussen TB, Belsham GJ, Bødker R, Bøtner A - Emerging Infect. Dis. (2012)

View Article: PubMed Central - PubMed

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Pools of culicoids were homogenized in water (100 µL) by using a 3-mm stainless steel bead (Dejay Distribution Ltd., Launceston, UK) in a TissueLyser II (QIAGEN, Hilden, Germany) for 1 min at 25 Hz... Two separate 1-step reverse transcription quantitative PCRs (RT-qPCRs), targeting the L segment and the S segment of SBV RNA, were performed according to protocols provided by the Friedrich Loeffler Institute in Germany on the extracted nucleic acids by using a Mx3005p qPCR system (Agilent Technologies, Palo Alto, CA, USA)... Another RT-qPCR targeting ruminant β-actin mRNA was performed as an internal endogenous control... This uptake of blood should therefore lead to a Ct value that is at least 6–7 units higher (≈100-fold lower level of RNA) when a single midge is tested by RT-qPCR... Thus, even if all 5 culicoids in a pool had recently taken a blood meal from a viremic animal, the Ct values observed here strongly suggest replication of SBV within the C. obsoletus group midges... However, in principle, other hosts of SBV could have a much higher level of viremia than cattle and could provide the levels of SBV RNA detected... C. punctatus s.s. midges cannot be ruled out as a possible vector of SBV because of the limited number of insects tested... Our study demonstrates the presence of SBV RNA in C. obsoletus group midges caught in Denmark during October 2011... The low Ct values (i.e., high SBV RNA levels) and the absence of ruminant β-actin mRNA in these samples strongly suggest that SBV replicates in these midges and hence that the C. obsoletus group midges are natural vectors for this virus.

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Location of trap site with culicoids positive for Schmallenberg virus (red dot), Hokkerup, Denmark, 2011.
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FA.1: Location of trap site with culicoids positive for Schmallenberg virus (red dot), Hokkerup, Denmark, 2011.

Mentions: In autumn 2011, culicoids were collected from several sites within Denmark. One site, a chicken farm in Hokkerup (Figure A1), was selected for study because of its location close (6 km) to the German border and proximity (<10 km) to an SBV-infected sheep farm in Germany, as reported on March 9, 2012, by the Friedrich Loeffler Institute surveillance website (www.fli.bund.de). The culicoids were collected during October 14–16 by using a Mosquito Magnet Independence trap (Mosquito Magnet, Lititz, PA, USA) baited with carbon dioxide and octenol. Midges were sorted manually into 91 specimens of the C. obsoletus group (comprising C. obsoletus, C. chiopterus, C. dewulfi, and C. scoticus) and 17 of the C. punctatus sensu stricto group, then stored at −20°C.


Culicoids as vectors of Schmallenberg virus.

Rasmussen LD, Kristensen B, Kirkeby C, Rasmussen TB, Belsham GJ, Bødker R, Bøtner A - Emerging Infect. Dis. (2012)

Location of trap site with culicoids positive for Schmallenberg virus (red dot), Hokkerup, Denmark, 2011.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3376822&req=5

FA.1: Location of trap site with culicoids positive for Schmallenberg virus (red dot), Hokkerup, Denmark, 2011.
Mentions: In autumn 2011, culicoids were collected from several sites within Denmark. One site, a chicken farm in Hokkerup (Figure A1), was selected for study because of its location close (6 km) to the German border and proximity (<10 km) to an SBV-infected sheep farm in Germany, as reported on March 9, 2012, by the Friedrich Loeffler Institute surveillance website (www.fli.bund.de). The culicoids were collected during October 14–16 by using a Mosquito Magnet Independence trap (Mosquito Magnet, Lititz, PA, USA) baited with carbon dioxide and octenol. Midges were sorted manually into 91 specimens of the C. obsoletus group (comprising C. obsoletus, C. chiopterus, C. dewulfi, and C. scoticus) and 17 of the C. punctatus sensu stricto group, then stored at −20°C.

View Article: PubMed Central - PubMed

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

Pools of culicoids were homogenized in water (100 µL) by using a 3-mm stainless steel bead (Dejay Distribution Ltd., Launceston, UK) in a TissueLyser II (QIAGEN, Hilden, Germany) for 1 min at 25 Hz... Two separate 1-step reverse transcription quantitative PCRs (RT-qPCRs), targeting the L segment and the S segment of SBV RNA, were performed according to protocols provided by the Friedrich Loeffler Institute in Germany on the extracted nucleic acids by using a Mx3005p qPCR system (Agilent Technologies, Palo Alto, CA, USA)... Another RT-qPCR targeting ruminant β-actin mRNA was performed as an internal endogenous control... This uptake of blood should therefore lead to a Ct value that is at least 6–7 units higher (≈100-fold lower level of RNA) when a single midge is tested by RT-qPCR... Thus, even if all 5 culicoids in a pool had recently taken a blood meal from a viremic animal, the Ct values observed here strongly suggest replication of SBV within the C. obsoletus group midges... However, in principle, other hosts of SBV could have a much higher level of viremia than cattle and could provide the levels of SBV RNA detected... C. punctatus s.s. midges cannot be ruled out as a possible vector of SBV because of the limited number of insects tested... Our study demonstrates the presence of SBV RNA in C. obsoletus group midges caught in Denmark during October 2011... The low Ct values (i.e., high SBV RNA levels) and the absence of ruminant β-actin mRNA in these samples strongly suggest that SBV replicates in these midges and hence that the C. obsoletus group midges are natural vectors for this virus.

Show MeSH
Related in: MedlinePlus