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Evaluation of matrix-assisted laser desorption/ionization time of flight mass spectrometry for the identification of ceratopogonid and culicid larvae.

22/11/2012 - SWITZERLAND - NOT OFFICIAL - Published paper

SUMMARY Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) was evaluated for the rapid identification of ceratopogonid larvae. Optimal sample preparation as evaluated with laboratory-reared biting midges Culicoides nubeculosus was the homogenization of gut-less larvae in 10% formic acid, and analysis of 02mg/ml crude protein homogenate mixed with SA matrix at a ratio of 1:15. Using 5 larvae each of 4 ceratopogonid species (C. nubeculosus, C. obsoletus, C. decor, and Dasyhelea sp.) and of 2 culicid species (Aedes aegypti, Ae. japonicus), biomarker mass sets between 27 and 33 masses were determined. In a validation study, 67 larvae belonging to the target species were correctly identified by automated database-based identification (91%) or manual full comparison (9%). Four specimens of non-target species did not yield identification. As anticipated for holometabolous insects, the biomarker mass sets of adults cannot be used for the identification of larvae, and vice versa, because they share only very few similar masses as shown for C. nubeculosus, C. obsoletus, and Ae. japonicus. Thus, protein profiling by MALDI-TOF as a quick, inexpensive and accurate alternative tool is applicable to identify insect larvae of vector species collected in the field.
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Simulating spread of Bluetongue Virus by flying vectors between hosts on pasture.

19/11/2012 - DENMARK - NOT OFFICIAL - Published paper

Bluetongue is a disease of ruminants which reached Denmark in 2007. We present a process-based stochastic simulation model of vector-borne diseases, where host animals are not confined to a central geographic farm coordinate, but can be distributed onto pasture areas. Furthermore vectors fly freely and display search behavior to locate areas with hosts. We also include wind spread of vectors, host movements, and vector seasonality. Results show that temperature and seasonality of vectors determines the period in which an incursion of Bluetongue may lead to epidemic spread in Denmark. Within this period of risk the number of infected hosts is affected by temperature, vector abundance, vector behavior, vectors' ability to locate hosts, and use of pasture. These results indicate that restricted grazing during outbreaks can reduce the number of infected hosts and the size of the affected area. The model can be implemented on other vector-borne diseases of grazing animals.
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First Phylogenetic Analysis Of Bluetongue Virus Serotype 4 Field Isolates From Argentina.

15/11/2012 - ARGENTINA - NOT OFFICIAL - Published paper

Bluetongue (BT) is an insect-transmitted viral disease of ruminant species and represents a major barrier for international trade of animals and their products. Bluetongue virus (BTV) has a genome composed by ten linear segments of double stranded RNA (dsRNA) which codify for at least ten different viral proteins. In South America, serological evidence for the presence of BTV has been found in Peru, Argentina, Brazil, Ecuador and Chile. Brazil and Argentina are the only countries where BTV has been isolated. In Brazil, a unique BTV isolate from serotype 12 has been reported and in Argentina five BTV 4 isolates has been obtained from cattle without clinical signs. Three of them were isolated during the years 1999-2001 and two new isolates were obtained as part of the present work. This study describes sequence comparisons and phylogenetic analyses of Seg-2, 3, 6, 7 and 10 from the first Argentinean field isolates of BTV. The analysis of segments 2 and 6 resulted in a single cluster of Argentinean sequences into the serotype 4 clade. In addition, the Argentinean sequences grouped within the nucleotype A clade, along with reference strains. The analysis of segments 3, 7 and 10 showed that the Argentinean isolates grouped into western topotype, indicating that the circulating virus had an African/European origin. The phylogenetic analysis revealed that Argentinean sequences presented a Southamerican genetic identity, assessed in every segment analysis, suggesting an independent lineage evolution.
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