Circoviridae. Circoviridae

Description of Circoviridae adapted from ICTVdb Virion Properties Morphology Virions consist of a capsid. During their life cycle, virions have an extracellular phase. Virus capsid is not enveloped. Virions are not tailed. Capsid/nucleocapsid is round and exhibits icosahedral symmetry (T=13). The capsid is isometric and has a diameter of 17-24 nm (size of particle diameter varies with type of stain used). Capsids appear round. The capsid surface structure reveals a regular pattern with distinctive features; is maintained using conventional electron microscopy. The capsid consists of 32 capsomers (that are hollow morphological subunits). Physicochemical and Physical Properties Virions have a buoyant density in CsCl of 1.33-1.37 g cm-3. There are 1 sedimenting component(s) found in purified preparations. The sedimentation coefficient is 91 S20w. Nucleic Acid The genome is monomeric; not segmented and contains a single molecule of circular, negative-sense, or ambisense, single-stranded DNA ; that forms a covalently closed circle. The complete genome is 1700-2000 nucleotides long. Proteins The viral genome encodes structural proteins and non-structural proteins. Lipids Lipids are not reported.