Comparison of bluetongue type 20 with certain viruses of the bluetongue and Eubenangee serological groups of orbiviruses.

The genome of bluetongue virus type 20 consists of 10 segments of double-stranded RNA each of which contains unique sequences as determined by oligonucleotide mapping. The 10 polypeptide products of the virus genome were detected in virus-infected cells, and in pulse--chase experiments there was no secondary cleavage of the primary gene products. Using stringent conditions for RNA--RNA reassociation, no significant homology could be detected between the genomes of bluetongue type 20 isolated in Australia and representative serotypes isolated in other geographic regions. The results suggest sequence divergence between geographically isolated viruses and not the recent introduction of a bluetongue virus into Australia.