Nucleic acid packaging in viruses

Abstract

Viruses protect their genetic information by enclosing the viral nucleic acid inside a protein shell (capsid), in a process known as genome packaging. Viruses follow essentially two main strategies to package their genome: Either they co-assemble their genetic material together with the capsid protein, or they assemble first an empty shell (procapsid) and then pump the genome inside the capsid with a molecular motor that uses the energy released by ATP hydrolysis. During packaging the viral nucleic acid is condensed to very high concentration by its careful arrangement in concentric layers inside the capsid. In this chapter we will first give an overview of the different strategies used for genome packaging to discuss later some specific virus models where the structures of the main proteins involved, and the biophysics underlying the packaging mechanism, have been well documented.