Secoviridae. Secoviridae

Description of Comoviridae adapted from ICTVdb Virion Properties Morphology Virions consist of a capsid. Virus capsid is not enveloped, round with icosahedral symmetry. The isometric capsid has a diameter of 28-30 nm. The capsid consists of 32 capsomers. Virus preparations contain more than one particle component. Physicochemical and Physical Properties Virions have a buoyant density in CsCl of 1.28-1.5 g cm-3. Nucleic Acid The genome is segmented; bipartite, segements are distributed among 2 particle types of linear, positive-sense, single-stranded RNA. The complete genome is 10000-15000 nucleotides long, is sequenced, complete sequence is about 6000-8000 nucleotides long, is sequenced, but only an estimate is available, complete sequence is 4000-7000 nucleotides long. The 5'-end of the genome has a genome-linked protein (VPg). The 3'-terminus has conserved nucleotide sequences. The 3'-terminus has a poly (A) tract. The multipartite genome is divided among different particles, each segment encapsidated separately and the segments are distributed between 2 different types of particles. The largest particles contain each one molecule of RNA-1 (sedimenting component B). The medium sized particles contain each one molecule of RNA-2 (sedimenting component M). The smallest particles contain no nucleic acid and are found in the top (sedimenting component T) band after sedimentation. Proteins The viral genome encodes structural proteins and non-structural proteins. Lipids Lipids are not reported. Genome Organization and Replication By itself, genomic nucleic acid is infectious. Description of Sequiviridae 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 about 30 nm. Capsids appear round. The capsomer arrangement is not obvious. Electron microscopic preparation and references: Virus preparation contains few virions. Physicochemical and Physical Properties Virions have a buoyant density in CsCl of 1.297-1.393-1.49 g cm-3. There are 1 sedimenting component(s) found in purified preparations, or 2 sedimenting component(s) found in purified preparations. The sedimentation coefficient is 153-156-159 S20w; of the other(s) are 60 S20w. A260/A280 ratio is 1.46-1.597-1.67. The thermal inactivation point (TIP) is at 57.5-61.87-65°C. The longevity in vitro (LIV) is 1-3.25-7 days. Although the titer is dependent on the host, the decimal exponent (DEX) of the dilution end point is usually around 3, or 4, or 5. Nucleic Acid The Mr of the genome constitutes 40% of the virion by weight. The genome is monopartite. Only one particle size of linear, positive-sense, single-stranded RNA is recovered. The genome is sequenced, and complete sequence is about 9000-12000 nucleotides long. The 5'-end of the genome has a probably genome-linked protein (VPg). Proteins The viral genome encodes structural proteins. Virions consist of 3 structural protein(s). Lipids Lipids are not reported. Genome Organization and Replication By itself, genomic nucleic acid is infectious (however, infectivity is protease-sensitive).