Analysis of the genomes of bluetongue virus serotype 10 vaccines and a recent BTV-10 isolate from Washington.

The 10 double-stranded RNA gene segments of 2 vaccinal strains of bluetongue virus (BTV) serotype 10 that are used in the United States (BTV CA8 California and BT-8 Colorado), and a BTV-10 isolate recently obtained from infected sheep in Washington (state) were characterized by oligonucleotide fingerprint analyses. It was determined that although the 2 BTV-10 vaccinal strains are genotypically distinct, they are closely related both to each other and to the United States prototype BTV-10 virus. The BTV-10 field isolate appears to be a naturally occurring reassortment virus with genome segments derived from both United States prototype BTV-10 and BTV-11 viruses. However, one RNA segment of the isolate was totally unlike the corresponding segments of United States prototype BTV-10, -11, -13 and -17 viruses.