0 Bruinsma, RF Gelbart, WM Reguera, D Rudnick, J Zandi, R 2003 PHYSICAL REVIEW LETTERS 90 JUN 20 COWPEA CHLOROTIC MOTTLE, ICOSAHEDRAL VIRUSES, MOSAIC VIRUS, PLANT-VIRUS, BETA-VIRUS, PROTEIN, PARTICLES, PACKING, CIRCLES, SPHERE <p>The protein shells, or capsids, of nearly all spherelike viruses adopt icosahedral symmetry. In the present Letter, we propose a statistical thermodynamic model for viral self-assembly. We find that icosahedral symmetry is not expected for viral capsids constructed from structurally identical protein subunits and that this symmetry requires (at least) two internal &quot;switching&quot; configurations of the protein. Our results indicate that icosahedral symmetry is not a generic consequence of free energy minimization but requires optimization of internal structural parameters of the capsid proteins.</p> http://dx.doi.org/10.1103/PhysRevLett.90.248101