CCMV capsids have 180 identical CPs that are organized in twelve identical pentamers and twenty identical hexamers. They are composed of six and five CPs, respectively. The red arrows in Figure 1 b indicate ring-like structures with apparent sixfold and fivefold symmetry known as hexamers and pentamers, respectively. Note that Figure 1 b has the orientation of the first panel of Figure 1 a. The various rotational symmetry operations coincide with those of the icosahedron (see Figure 1 a). The capsid also has threefold and fivefold rotation axes. Figure 1 b is oriented along a twofold symmetry axis. The regular surface structure of the CCMV capsid resembles a crystal and, like a crystal, it can be characterized by its symmetry operations. Figure 1 b shows an image of the CCMV capsid, reconstructed by cryotransmission electron microscopy and X-ray diffraction methods ( 4, 5). The physical properties of CCMV have been extensively studied, and CCMV is applied extensively in materials and medical science. Like TMV, CCMV self-assembles spontaneously ( 3). 2.вЂ‚THE STRUCTURE OF VIRAL CAPSIDS 2.1.вЂ‚The Cowpea Chlorotic Mottle VirusДЇigure 1 shows the Cowpea chlorotic mottle virus (CCMV), a roughly spherical virus with a radius of approximately 15 nm that infects the cowpea plant. This review discusses the application of methods borrowed from statistical physics, condensed matter physics, soft-matter physics, and elasticity theory to the self-assembly and material properties of viral capsids. Functionalized viral shells have been used to create metallic wires, solar cells, batteries, and fuel cells ( 2). Directed evolution of the CPs allows attachment of particular receptor groups on the exterior surface. Because of their highly reproducible size and shape and their precise structural organization, the shells of viruses, or capsids, have since been found to have many applications in materials science.

In 1955, Fraenkel-Conrat & Williams ( 1) showed that the rod-like Tobacco mosaic virus (TMV) assembles spontaneously in solutions containing the molecular components of the virus.

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