The
virions of
Tectiviridae species are non-enveloped, icosahedral and display a pseudo T=25 symmetry. The
capsid has two layers. The outer layer is a protein structure of 240 capsid proteins trimers, and the inner one is a proteinaceous lipid membrane which envelopes the virus
genome. Apical spikes extending about 20
nanometers (nm) protrude from the icosahedrons vertices. The genome is a single molecule of linear double-stranded
DNA of 15 kilo
bases in length, and has 30 open reading frames. It forms a tightly packed coil and encodes several structural proteins. It encodes about 30 proteins that are transcribed in operons. At least 9 structural proteins are present in the viron. The genome is about 66 mega
daltons in weight and constitutes 14–15% of the virion by weight.
Lipids constitute a further 15% by weight.
Carbohydrates are not present. ==Life cycle==