''Lagovirus'' is a genus of

virus A virus is a submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are ...

es, in the family ''

Caliciviridae The ''Caliciviridae'' are a family of "small round structured" viruses, members of Class IV of the Baltimore scheme. Caliciviridae bear resemblance to enlarged picornavirus and was formerly a separate genus within the picornaviridae. They are ...

''.

Lagomorph The lagomorphs () are the members of the taxonomic order Lagomorpha, of which there are two living families: the Leporidae (rabbits and hares) and the Ochotonidae ( pikas). There are 110 recent species of lagomorph, of which 109 species in t ...

s serve as natural hosts. There are two species in this genus. Diseases associated with this genus include: necrotizing hepatitis leading to fatal hemorrhages.

Taxonomy

The genus contains the following species: * '' European brown hare syndrome virus'' * '' Rabbit hemorrhagic disease virus''

Virion properties

Morphology

Virions consist of a

capsid A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or m ...

. The capsid is not enveloped, round with T=3

icosahedral symmetry In mathematics, and especially in geometry, an object has icosahedral symmetry if it has the same symmetries as a regular icosahedron. Examples of other polyhedra with icosahedral symmetry include the regular dodecahedron (the dual polyhedr ...

. The isometric capsid has a diameter of 35–39 nm. Particles with T=1 symmetry, composed of 60 capsid proteins are also observed, which have diameter of about 15 nm. Capsids appear round to

hexagonal In geometry, a hexagon (from Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon. The total of the internal angles of any simple (non-self-intersecting) hexagon is 720°. Regular hexagon A regular hexagon is d ...

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.

Life cycle

Viral replication is cytoplasmic. Entry into the host cell is achieved by attachment to host receptors, which mediates endocytosis. Replication follows the positive stranded RNA virus replication model. Positive stranded RNA virus transcription is the method of transcription. Translation takes place by RNA termination-reinitiation. Lagomorphs serve as the natural host.

Physical and chemical properties

The

molecular mass The molecular mass () is the mass of a given molecule, often expressed in units of daltons (Da). Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element. The derived quan ...

(Mr) of virions is 15. Virions have a buoyant density in

Caesium chloride Caesium chloride or cesium chloride is the inorganic compound with the formula Caesium, CsChloride, Cl. This colorless salt is an important source of caesium ions in a variety of niche applications. Its crystal structure forms a major structural ...

(CsCl) of 1.33–1.36 g/cm³. The density gradient of virions in Potassium Tartrate-Glycerol is 1.29 g/cm³. The

sedimentation coefficient In chemistry, the sedimentation coefficient () of a particle characterizes its sedimentation (tendency to settle out of suspension) during centrifugation. It is defined as the ratio of a particle's sedimentation velocity to the applied accelera ...

is 170–187

svedberg In chemistry, a Svedberg unit or svedberg (symbol S, sometimes Sv) is a non- SI metric unit for sedimentation coefficients. The Svedberg unit offers a measure of a particle's size indirectly based on its sedimentation rate under acceleration ...

(s_20,w); of the other(s) are peak 160–170

(s_20,w) (believed to consist of defective interfering particles). Under

in vitro ''In vitro'' (meaning ''in glass'', or ''in the glass'') Research, studies are performed with Cell (biology), cells or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in ...

conditions virions are inactivated in acid environment of pH 4.5–7; stable in

alkaline In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The ...

environment of pH 7–10.5. Virions are not stable at raised temperature in presence of high concentration of Mg⁺⁺. Virions are sensitive to treatment with

trypsin Trypsin is an enzyme in the first section of the small intestine that starts the digestion of protein molecules by cutting long chains of amino acids into smaller pieces. It is a serine protease from the PA clan superfamily, found in the dig ...

(in some strains, not sensitive to treatment with mild detergents, or

ether In organic chemistry, ethers are a class of compounds that contain an ether group, a single oxygen atom bonded to two separate carbon atoms, each part of an organyl group (e.g., alkyl or aryl). They have the general formula , where R and R� ...

, or

chloroform Chloroform, or trichloromethane (often abbreviated as TCM), is an organochloride with the formula and a common solvent. It is a volatile, colorless, sweet-smelling, dense liquid produced on a large scale as a precursor to refrigerants and po ...

. The

infectivity In epidemiology, infectivity is the ability of a pathogen In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be refer ...

is enhanced after treatment with trypsin (in some strains).

Genome

The

genome A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as ...

is not segmented and contains a single molecule of linear positive-sense, ss

RNA Ribonucleic acid (RNA) is a polymeric molecule that is essential for most biological functions, either by performing the function itself (non-coding RNA) or by forming a template for the production of proteins (messenger RNA). RNA and deoxyrib ...

. Minor species of non-

genomic Genomics is an interdisciplinary field of molecular biology focusing on the structure, function, evolution, mapping, and editing of genomes. A genome is an organism's complete set of DNA, including all of its genes as well as its hierarchical, ...

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. The complete genome is 7450

nucleotides Nucleotides are Organic compound, organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both o ...

long. The genome has a

guanine Guanine () (symbol G or Gua) is one of the four main nucleotide bases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, and thymine ( uracil in RNA). In DNA, guanine is paired with cytosine. The guanine nucleoside ...

cytosine Cytosine () (symbol C or Cyt) is one of the four nucleotide bases found in DNA and RNA, along with adenine, guanine, and thymine ( uracil in RNA). It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attac ...

content of 49.3–50.1 %. 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 viral structural protein. Virions consist of 1 structural protein(s) (major species located in the capsid. Viral structural protein: Capsid protein has a

molar mass In chemistry, the molar mass () (sometimes called molecular weight or formula weight, but see related quantities for usage) of a chemical substance ( element or compound) is defined as the ratio between the mass () and the amount of substance ...

of 59000–71000 Da; is the coat protein. Capsid protein has a molecular mass of minor 'soluble' 28–30 k Da.

Antigenicity

Cross-reactivity is found. Cross-reactivity between species of the same

serotype A serotype or serovar is a distinct variation within a species of bacteria or virus or among immune cells of different individuals. These microorganisms, viruses, or Cell (biology), cells are classified together based on their shared reactivity ...

, but not with species of another serotype and some species of the same serotype, but not with all. Although the degree of antigenic specificity varies with the degree of relatedness, the antigenicity is distinct from serogroups of the same genus. Most species in the genus are related antigenically. They are sharing some epitopes in the structural proteins.

References

* ICTVdB Management (2006). 00.012.0.02. Lagovirus. In: ICTVdB—The Universal Virus Database, version 4. Büchen-Osmond, C. (Ed), Columbia University, New York, USA

External links

ICTV Report: ''Caliciviridae''

{{Use dmy dates, date=April 2017 Caliciviridae Animal viral diseases Virus genera Leporid diseases