The Atomic Structure of the Bluetongue Virus Core

The structure of the core particle of bluetongue virus has been determined by X-ray crystallography at a resolution approaching 3.5 A. This transcriptionally active compartment, 700 A in diameter, represents the largest molecular structure determined in such detail. The atomic structure indicates how approximately 1,000 protein components self-assemble, using both the classical mechanism of quasi-equivalent contacts, which are achieved through triangulation, and a different method, which we term geometrical quasi-equivalence.