What are the basic components of virions?

The simplest virions consist of two basic components – A nucleic acid core and a protein coat. The nucleic acid is the most important component of a virion. This nucleic acid core may consist of either RNA or DNA, which may be single-stranded or double-stranded. The protein shell encapsulates the structure and is called the capsid. The capsid performs two important functions. It protects the viral genome from nucleases and during infection it attaches the virion to specific receptors exposed on the prospective host cell. Together, the nucleic acid and protein shell forms the nucleocapsid.