Elasticity and mechanical response of viral capsids

A virus consists of genetic material encapsulated in a protective shell known as a "capsid". The capsid usually consists of an aggregate of many copies of identical proteins that spontaneously form a hollow shell which can be nearly spherical or can have flat facets in the shape of an icosahedron. Widom and collaborators have studied the elasticity of capsids using methods of continuum elastic theory and coarse-grained network models. Through considerations of symmetry they have classified the universal shapes of low-lying vibrational modes and demonstrated a soft-mode transition between spherical and icosahedral shapes.