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Title: Report of the Bluetongue and Bovine Retroviruses Committee.

item Wilson, William
item Drolet, Barbara
item Mecham, James
item Miller, Myrna
item Reeves, Will

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 10/25/2008
Publication Date: 6/30/2009
Citation: Wilson, W.C., Drolet, B.S., Mecham, J.O., Miller, M.M., Reeves, W.K. 2009. Report of the Bluetongue and Bovine Retroviruses Committee.. Meeting Abstract.

Interpretive Summary: Arthropod-Borne Animal diseases Research Laboratory scientists made presentations during the iation’s Bluetongue and Bovine Retroviruses Committee meeting at the annual meeting. Dr. Reeves presented New strategies for preventing bluetongue in sheep. Dr. Miller reported on investigations of an outbreak of BTV serotype 17 in Wyoming. Dr. Mecham discussed an update on the BTV detection using Culicoides cells. Dr. Wilson presented an update on a new genetic amplification assay for detection and distinction of BTV and the related Epizootic Hemorrhagic Disease Viruses. An update of the ABADRL BTV research and plans to assess the risk of the BTV serotype 8 caused severe disease in Europe to the U.S. was presented by Dr. Drolet.

Technical Abstract: New strategies for preventing bluetongue in sheep, W.K. Reeves. Bluetongue disease is a sporadic and unpredictable disease in the northern Rocky Mountains. Epizootics can be separated by decades of little to no disease activity. Woolgrowers need access to control technologies that can be used after an outbreak is detected. We tested 6 formulations of midge repellent pesticides against Culicoides sonorensis, the primary vector of bluetongue in the western USA. Synthetic pyrethroids with PBO (a synergist) applied with both ear tags and a low volume spray were effective in repelling biting midges for up to 5 weeks. These pesticides are low cost and can be applied during an outbreak and might protect sheep during the autumn until freezing weather sets in and kills the biting midges. Investigation of an Outbreak of Bluetongue serotype 17 in sheep in Wyoming, M.M. Miller, a report was provided on investigation of an outbreak of Bluetongue Virus serotype 17 in sheep from the Big Horn Basin of Wyoming new BTV intrusion into a naïve population and elevation might be the primary barrier to vector movement. The infection rate closely reflected the reported morbidity. Disease varied between locations suggesting that ranch level vector control strategies might be effective in minimizing infections. The investigation indicated that sheep naturally infected are not a long-term source of infectious virus. Update on bluetongue antigen detection in Culicoides cells, J. Mecham. An update was provided to the committee on research at the ABADRL to develop improved techniques for detecting bluetongue virus (BTV) in insect cells. He reported on the development of both an endpoint titration and an agarose overlay assay using In situ immune infrared fluorescent staining techniques to directly detect and titrate BTV in Culicoides cell culture. The sensitivity of these assays for detection and titration of virus in Culicoides cells was comparable or superior to that obtained by standard techniques in vertebrate cell culture. These assays will have application for both virus isolation and research using the insect cells lines. Improved RNA extraction increases sensitivity of the bluetongue and epizootic hemorrhagic virus multiplex real-time RT-PCR, W. Wilson. An update on improved protocols for the Multiplex real-time RT-PCR for detection of all serotypes of BTV and EHDV was provided. The assay can distinguish between BTV and EHDV RNA. The Arthropod-Borne Animal Diseases Research Laboratory: Research Program; Update and Current Status, B.S. Drolet. The Arthropod-Borne Animal Diseases Research Laboratory (ABADRL) is located in Laramie Wyoming. Currently the ABADRL staff consists of microbiologists, virologists, entomologists, and veterinarians. Currently the facilities have been renovated and approved by APHIS for BSL-2 lab, small animal, insect, and large animal work. To accomplish their BSL-3 research mission, the ABADRL is contracting work out, establishing more collaborations with scientists who have access to BSL-3 facilities. The ABADRL has three 5-year project plans under two ARS National Research Programs. Two project plans under the Animal Health National Program is entitled “Countermeasures to control and eradicate Rift Valley fever” and “Virus-vector-host interactions of arboviral diseases of livestock.” The second focuses primarily on bluetongue virus (BTV) and vesicular stomatitis virus (VSV). The project plan, under the Veterinary Medical, and Urban Entomology National Program, is entitled “Vector competence and protection of US livestock and wildlife from arthropod-borne diseases” which includes research on important vector insect species of mosquitoes, midges, and sand flies and important arboviruses such as BTV, RVFV, and epizootic hemorrhagic disease virus (EHDV).