Astroviridae. Astroviridae

Description of Astroviridae adapted from ICTVdb Virion Properties Morphology Virions consist of a capsid. Virus capsid is not enveloped, round with polyhedral symmetry. The isometric capsid has a diameter of 27-30 nm. Capsids appear round. The capsid surface structure reveals a regular pattern with distinctive star-like features with five or six points. The capsomer arrangement is clearly visible. Surface projections are small spikes protruding from the 12 vertices that make the surface to appear rough . Physicochemical and Physical Properties Virions have a buoyant density in CsCl of 1.36-1.39 g cm-3. Nucleic Acid The genome is not segmented and contains a single molecule of linear, positive-sense, single-stranded RNA. The complete genome is about 6800-7900 nucleotides long. The genome has a guanine + cytosine content of 45-47 %. The 3'-terminus has a poly (A) tract. Each virion contains a longer than full length copy. Proteins The viral genome encodes structural proteins. Lipids Lipids are absent.