Epsilon 15's capsid is composed of many interlocking protein units. The most prominent surface protein, called gp7, joins together in asymmetrical groups of seven. In the image above, each individual gp7 in a given cluster has a different color. These clusters repeat across the entire surface of the capsid. Below the sphere, in gray, is a cross-sectional map of the inside of the virus. The rings indicate its packaged DNA genome.