The highly ordered double-stranded RNA genome of bluetongue virus revealedby crystallography

The concentration of double-stranded RNA within the bluetongue virus core r enders the genome segments liquid crystalline. Powder diffraction rings con firm this local ordering with a 30 Angstrom separation between strands. Det ermination of the structure of the bluetongue virus core serotype 10 and co mparison with that of serotype 1 reveals most of the gc nomic double-strand ed RNA, packaged as well-ordered layers surrounding putative transcription complexes at the apices of the particle. The outer layer of RNA is sufficie ntly well ordered by interaction with the capsid that a model can be built and extended to the less-ordered inner layers, providing a structural frame work for understanding the mechanism of this complex transcriptional machin e. We show that the genome segments maintain local order during transcripti on.