Structure of virions. Illustration of three types of basic structure for virions (virus particles). At left is a rod-shaped virion with proteins (orange) surrounding a helically coiled nucleic acid molecule (blue). An example is a tobamovirus. At centre is an isometric virion with a protein coat (orange) in an icosahedral shape around a nucleic acid core (blue). An example is a picornavirus. At right is an enveloped virion, with an isometric virion (orange) enclosed in a lipoprotein envelope (blue). An example is a coronavirus. For this artwork with labels, see C023/8890.