Viruses and their protein capsids can be regarded as biologically evolved nanomachines able to perform multiple, complex biological functions through coordinated mechano-chemical actions during the infectious cycle. The advent of nanoscience and nanotechnology has opened up, in the last 10 years or so, a vast number of novel possibilities to exploit engineered viral capsids as protein-based nanoparticles for multiple biomedical, biotechnological or nanotechnological applications. This chapter attempts to provide a broad, updated overview on the self-assembly and engineering of virus capsids, and on applications of virus-based nanoparticles. Different sections provide outlines on: (i) the structure, functions and properties of virus capsids; (ii) general approaches for obtaining assembled virus particles; (iii) basic principles and events related to virus capsid self-assembly; (iv) genetic and chemical strategies for engineering virus particles; (v) some applications of engineered virus particles being developed; and (vi) some examples on the engineering of virus particles to modify their physical properties, in order to improve their suitability for different uses.
Keywords: Capsid; Capsid assembly; Capsid proteins and building blocks; Capsid structure, function and properties; Capsid-based vaccines; Chemical functionalization; Diagnostic imaging; Gene therapy; Inorganic nanoparticles; Nanobiosensors; Nanoscale materials; Phage display; Protein engineering; Targeted drug delivery; Virion; Virotherapy; Virus; Virus capsid stability; Virus capsid-based nanoparticle; Virus-like particle.