Project name: Caliciviridae

Description: Description of Caliciviridae 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 35-39 nm. Capsids appear round to hexagonal in outline. The capsid surface structure reveals a regular pattern with distinctive features. The capsomer arrangement is clearly visible. Capsid with 32 cup-shaped depressions. Physicochemical and Physical Properties The molecular mass (Mr) of virions is 15 x 106. Virions have a buoyant density in CsCl of 1.33-1.4 g cm-3. The density of virions is in glycerol-potassium tartrate gradients 1.29 g cm-3. The sedimentation coefficient is 170-187 S20w; of the other(s) are peak 160-170 S20w (believed to consist of defective interfering particles). Under in vitro conditions virions are stable in acid environment of pH 4-5. Virions are not stable at raised temperature in presence of high concentration of Mg++. Virions are sensitive to treatment with trypsin (in some strains, not sensitive to treatment with mild detergents, or ether, or chloroform. The infectivity is enhanced after treatment with trypsin (in some strains). Nucleic Acid The genome is not segmented and contains a single molecule of linear positive-sense, single-stranded RNA. Minor species of non-genomic nucleic acid are some times also found in virions. The encapsidated nucleic acid is mainly of genomic origin, but virions may also contain subgenomic RNA (in some members). The complete genome is 7400-8300 nucleotides long. The genome has a guanine + cytosine content of 45-56 %. The 5'-end of the genome has a usually genome-linked protein (VPg), or methylated nucleotide cap (in the case of hepatitis E virus). The 3'-terminus has a poly (A) tract. Each virion contains a full length copy, or defective interfering copies. Proteins The viral genome encodes structural proteins. Virions consist of 1 structural protein (major species), or 2 structural proteins detected in Norwalk virus, amyelosis chronic stunt virus and porcine enteric calicivirus located in the capsid. Structural Proteins: Capsid protein has a molecular mass of 58000-60000 Da; is the coat protein. Capsid protein has a molecular mass of minor 'soluble' 28-30 kDa. Lipids Lipids are not reported. Genome Organization and Replication By itself, genomic nucleic acid is infectious. Transcription: Sub-genomic RNA is present in infected cells (after infection with e.g., rabbit hemorrhagic disease virus (RHDV)).

Last updated: 2006-10-10