A virus is biological nanoparticle with a size of 20 to 500 nm. A virus is a biological infective agent that infect living hosts and reproduces inside the host cells. Viral infect all forms of life; can cause disease in humans, animals, plants and even insects. Unlike most living things, viruses do not have cells that divide; new viruses are assembled in the infected host cells. Viruses contain genetic materials (either DNA or RNA) which give them the ability to mutate and evolve. It also has a protective coat termed the capsid which is made up of multiple numbers of protein monomers called capsomer. Every year novel viruses emerged with the potential to cause disease and death worldwide. Today, over 5000 species of viruses have been discovered and described.

Virus nanotechnology is one of the very promising and emerging field of research. A highly interdisciplinary field, viral nanotechnology occupies the interface between virology, biotechnology, chemistry, and materials science. The fields employ viral nanoparticles (VNPs) and its counterparts of virus-like nanoparticles (VLPs) for potential applications in the diverse fields of electronics, sensors, and most significantly at clinical field. VNPs and VLPs are attractive building blocks for several reasons. Both particles are on the nanometer-size scale; they are monodispersed with a high degree of symmetry and polyvalency; they can be produced with ease on large scale; they are exceptionally stable and robust, and they are biocompatible, and in some cases, orally bioavailable. They are "programmable" units that can be modified by either genetic modification or chemical bioconjugation methods.

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