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K.M. Reinisha, M.L. Nibertb & S. C. Harrisona,c
aHarvard University, bDepartment of Biochemistry and Institute for Molecular Virology, Univ. of Wisconsin-Madison, Madison, WI, cHoward Hughes Medical Institute, Cambridge, MA

[Nature, Vol 404, 960-967 (2000).]

Reoviruses infect the respiratory and intestinal tracts of mammals and birds. Although infections seldom cause disease, reoviruses are related to other more serious viruses. The family reoviridae includes a large number of double-stranded RNA viruses infecting vertebrates, invertebrates, and plants.


Synchrotron radiation is the only tool available for the determination of very large molecular structures at high resolution such as the reovirus core. One of the largest structures solved to-date has been reported from work carried out at MacCHESS by Karin Reinish in the Harrison group at Harvard. The reovirus core is a macromolecular assembly with a molecular mass of 52 million. The core synthesizes, modifies, and exports viral messenger RNA. The core contains five of the eight proteins that make up a complete virion and is about 700 Angstroms in diameter. They crystallize in a centered cubic space group with unit cell dimensions of 1255 Angstrom with crystal growth requiring 9 to 12 months. Using the CHESS F1 facility, one of the two Biosafety Level 2 facilities in the US, scientists have been able to "see" into the three-dimensional structure of the core using the tools of x-ray crystallography.

The reovirus core particle shows the subunits in different colors. There are 120 copies of the part in red that forms the shell and that packages the RNA. This part defines the symmetry and size of the particle. Other subunits, shown in yellow, green and white stabilize the shell. The blue parts form turret-like structures around the fivefold axes that exports mature mRNA into the cytoplasm of the infected cell.

Learning how this assembly works is one important step in learning how to control what hazardous viruses can do to mankind.