Author
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MECHAM, JAMES |
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Submitted to: American Society for Virology Meeting
Publication Type: Abstract Only Publication Acceptance Date: 7/14/2003 Publication Date: 7/14/2003 Citation: Mecham, J.O. 2003. Evidence for reassortment in the natural history of bluetongue virus serotype 2. American Society for Virology Meeting. Interpretive Summary: Bluetongue virus serotype 2 (BTV-2) is the most recent bluetongue serotype to be introduced into the U.S. It was first isolated from sentinel cattle and Culicoides insignis at Ona, Florida in 1982. The initial isolates represented two RNA electropherotypes and were designated Ona-A and Ona-B. The Ona-A electropherotype was identical to the South African BTV-2 prototype. Ona-A was isolated in September and October of 1982 and then disappeared. Ona-B isolations were made in late October and November at the same site and at additional sites in Florida the following year. Ona-B isolations were subsequently made in 1984 and 1985 from cattle in Alabama. It was widely assumed that BTV-2 disappeared from the southeastern U.S., since no isolations had been reported since 1987. However, a recent isolate of BTV-2 from sheep in Florida suggests that this serotype was either reintroduced or has persisted since its first appearance in 1982. To investigate this question, genes coding for VP2, VP7 and NS2 were sequenced from this recent isolate. The sequences were compared to those of the prototype South African isolate, the original Ona-A and Ona-B isolates, and to recent isolates of BTV-13 and BTV-17 from Florida. Phylogenetic analyses suggest that mixed infections and reassortment generated the Ona-B variant. The data also indicate that this reassortant BTV-2 has persisted in the southeastern U.S. for the past 20 years. Technical Abstract: Bluetongue virus serotype 2 (BTV-2) is the most recent bluetongue serotype to be introduced into the U.S. It was first isolated from sentinel cattle and Culicoides insignis at Ona, Florida in 1982. The initial isolates represented two RNA electropherotypes and were designated Ona-A and Ona-B. The Ona-A electropherotype was identical to the South African BTV-2 prototype. Ona-A was isolated in September and October of 1982 and then disappeared. Ona-B isolations were made in late October and November at the same site and at additional sites in Florida the following year. Ona-B isolations were subsequently made in 1984 and 1985 from cattle in Alabama. It was widely assumed that BTV-2 disappeared from the southeastern U.S., since no isolations had been reported since 1987. However, a recent isolate of BTV-2 from sheep in Florida suggests that this serotype was either reintroduced or has persisted since its first appearance in 1982. To investigate this question, genes coding for VP2, VP7 and NS2 were sequenced from this recent isolate. The sequences were compared to those of the prototype South African isolate, the original Ona-A and Ona-B isolates, and to recent isolates of BTV-13 and BTV-17 from Florida. Phylogenetic analyses suggest that mixed infections and reassortment generated the Ona-B variant. The data also indicate that this reassortant BTV-2 has persisted in the southeastern U.S. for the past 20 years. |
