The Big Picture Book of Viruses: Caliciviridae



Taxonomy: Comments: Viruses with typical calicivirus morphology have been identified in other animal species including humans, other primates, cattle, mink, swine, walruses, dolphins, dogs, rabbits, chickens, reptiles, amphibians and insects, but none of these have been fully characterised. Those from humans and some other species cause gastroenteritis, and are difficult to propagate in cell culture. Other viruses that cause gastroenteritis in humans, generally designated "small round structured viruses", including Norwalk virus and Snow Mountain agent, lack typical calicivirus morphology, but have buoyant density and a single capsid polypeptide typical of caliciviruses.

Limited serological relationships have been found among strains of viruses from humans: little or no serological relationships have been detected among viruses from other species.

Host: Virus infects vertebrates and invertebrates.

Genome: RNA. Single stranded. Linear; genomic nucleic acid positive sense. Genome monopartite. Total genome 7900 nucleotides long. 5' terminus has a genome-linked protein (VPg). 3' terminus has a poly (A) tract.

Morphology: Distinct viral structures visible in thin sections of infected tissue; virions not enveloped. Capsids isometric. Nucleocapsid with 32 cup-shaped depressions. Nucleocapsids with obvious regular surface structure; 35-39 nm in diameter. Symmetry icosahedral. Nucleocapsids appear to be round to appear to be angular. Surface capsomer arrangement obvious.

(Note: for more information about the taxonomy and structure of this virus, see the ICTV database below.)

More Information:
Taxonomy: ICTV Data
WWW Sites: ATV Sites!
Tutorials: None Available

Caliciviridae Images:

EM Images Example Virus Name Description of Image

  • Genus Calicivirus
  • N/A
    Vesicular exanthema of swine virus
    Norwalk virus Norwalk virus (NV) is a major cause of epidemic acute and mild gastroenteritis, or diarrhea, in older children and adults. The first recorded epidemic attributed to Norwalk virus occured in an elementary school in Norwalk, Ohio, in 1968. Bacteria-free fecal filtrates derived from adult patients were fed to volunteers. These volunteers consequently became ill and provided evidence that gastroenteritis could be induced with a nonbacterial agent. In 1972, NV was first seen using Immuno-EM. By 1990, molecular cloning was allowing detailed sequence and expression of the capsid protein. The first 3-dimensional reconstruction of NV capsid was accomplished in 1994, using cryo-EM techniques, at 22 angstroms resolution.

    Dr. B.V.Venkataram Prasad's Lab in the W.M. Keck Center for Computational Biology at Baylor College of Medicine. The long-term objective of his research group is to understand the molecular mechanisms that regulate the biological activities in the life cycles of medically important viruses, in order to develop anti-viral strategies. Their current focus is to establish structure-function correlations in viruses that cause gastroenteritis in humans. These viruses include members of the viral families reoviridae and caliciviridae.

    Calicivirus Note the 'Star of David' image exhibited by individual virus particles. This is distinct from the star-like images exhibited by astrovirus particles. Bar = 50 nanometers. Source: Stool sample from an individual with gastroenteritis. Method: Negative-stain Transmission Electron Microscopy. By F.P. Williams, U.S. Environmental Protection Agency.
    Norwalk Virus

    A comparison of the three-dimentional structures of recombinant Norwalk Capsid (rNV capsid) and primate calicivirus determined to be 22Å resolution using electron cryomicroscopy and computer image processing techniqes.

    Dr. B.V.Venkataram Prasad's Lab in the W.M. Keck Center for Computational Biology at Baylor College of Medicine. The long-term objective of his research group is to understand the molecular mechanisms that regulate the biological activities in the life cycles of medically important viruses, in order to develop anti-viral strategies. Their current focus is to establish structure-function correlations in viruses that cause gastroenteritis in humans. These viruses include members of the viral families reoviridae and caliciviridae.

    Norwalk Virus Note the ill-defined somewhat lace-like appearance of individual virus particles. The virus particles of Norwalk and other SRSVs (Small Round Structured Viruses) exhibit a characteristic appearance that is distinct from the featureless appearance of poliovirus. It is also distinct from other small viruses such as astrovirus, and typical (non-SRSV) calicivirus. Bar = 50 nanometers. Source: Stool sample from an individual with gastroenteritis. Method: Negative-stain Transmission Electron Microscopy. By F.P. Williams, U.S. Environmental Protection Agency.
    em_norwa
    Norwalk virus an example virus image from the ICTV
    gradyp1
    Norwalk virus Typical morphology of Norwalk-like viruses seen by transmission electron microscopy. The individual virions have a diameter of only 27nm.From the Wadsworth Center of the New York State Department of Health.
    em_calic
    a Calicivirus an example virus image from the ICTV
    vsd19a
    Bovine calicivirus From Stewart McNulty at Veterinary Sciences, Queen's University, Belfast.
    vsd20a
    Pig calicivirus From Stewart McNulty at Veterinary Sciences, Queen's University, Belfast.
    smith2a
    Cetacean Calicivirus Tursiops - 1 (CCVTur-1) Negative staining using phosphotungstic acid on a carbon-coated grid showing typical surface cup morphologic features as commonly seen by electron microscopy. Bar = 100 nm. From the NCID, of the CDC.
    (provisional)
    hep62
    Hepatitis E Based on similar physicochemical and biologic properties, HEV has been provisionally classified in the Caliciviridae family; however, the organization of the HEV genome is substantially different from that of other caliciviruses and HEV may eventually be classified in a separate family. From the NCID, of the CDC.


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