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Title: MOLECULAR EPIDEMIOLOGY OF BLUETONGUE VIRUS IN NORTHERN COLORADO

Author
item White, David
item BLAIR, CAROL - COLORADO STATE UNIV
item BEATY, BLAIR - COLORADO STATE UNIV

Submitted to: Virus Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/7/2005
Publication Date: 6/1/2006
Citation: White, D.M., Blair, C.D., Beaty, B. 2006. Molecular epidemiology of bluetongue virus in northern colorado. Virus Research.

Interpretive Summary: Bluetongue virus (BTV), an economically important virus of domestic and wild ruminants that is carried by the biting gnat Culicoides sonorensis, is well established in the western and south-eastern parts of the United States. Discovering the details of the natural movement of the virus within an between established foci could lead to novel assessment or control strategies. The behavior of Bluetongue virus serotype 11 (BTV11) in an endemic focus in northern Colorado was investigated. Viruses isolated up to 13 years apart, from both animal and insect hosts, were compared by genetic analysis of three genome segments - L2, S7, and S10. For each segment, viruses isolated from ruminants in the 1980's were more similar to one another than to viruses isolated from Culicoides spp. insects in the 1990's. Nearly identical BTV11-L2 segments were found in all isolates, but they were associated with a succession of different S7 and S10 genome segments, each appearing to displace the previous one. Therefore, the commonly used, L2-segment-based serologic identification of BTV underestimates the origin and natural evolution of BTV. In addition, the use of one or even two genome segments to identify a viral population of BTV is inadequate to define the potential for evolution of the virus in an endemic focus. This information could influence both import/export regulations based on BTV epidemiology, as well as our view of the natural biology of the virus.

Technical Abstract: The molecular epidemiology of Bluetongue virus serotype 11 (BTV11) in an endemic focus in northern Colorado was investigated. Viruses isolated up to 13 years apart, from both vertebrate and invertebrate hosts, were compared by phylogenetic analysis of sequence data from three genome segments - L2, S7, and S10. For each segment, viruses isolated from ruminants in the 1980's were more similar to one another than to viruses isolated from Culicoides spp. insects in the 1990's. Nearly identical BTV11-L2 segments were found in all isolates, but they were associated with a succession of different S7 and S10 genome segments, each appearing to displace the previous one. Therefore, the commonly used, L2-segment-based serologic identification of BTV underestimates the origin and natural evolution of BTV. In addition, the use of one or even two genome segments to identify a viral population of BTV is inadequate to define the molecular epidemiology of the virus in an endemic focus. This information could influence both import/export regulations based on BTV epidemiology, as well as our view of the natural biology of the virus.