''Lagovirus'' is a genus of

virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1 ...

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 p ...

''.

Lagomorph The lagomorphs are the members of the taxonomic order Lagomorpha, of which there are two living families: the Leporidae (hares and rabbits) and the Ochotonidae (pikas). The name of the order is derived from the Ancient Greek ''lagos'' (λαγ� ...

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 Rabbit hemorrhagic disease (RHD), also known as viral hemorrhagic disease (VHD), is a highly infectious and lethal form of viral hepatitis that affects European rabbits. Some viral strains also affect hares and cottontail rabbits. Mortality rate ...

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 may ...

. 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 of the ...

. 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'' has ...

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 (''m'') is the mass of a given molecule: it is measured in daltons (Da or u). Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element. The related quanti ...

(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 Cs Cl. This colorless salt is an important source of caesium ions in a variety of niche applications. Its crystal structure forms a major structural type where each ...

(CsCl) of 1.33–1.36 g/cm³. The

density gradient Density gradient is a spatial variation in density over an area. The term is used in the natural sciences to describe varying density of matter, but can apply to any quantity whose density can be measured. Aerodynamics In the study of supersonic ...

of virions in

Potassium Tartrate-Glycerol Potassium is the chemical element with the Symbol (chemistry), symbol K (from New Latin, Neo-Latin ''wikt:kalium#Latin, kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little fo ...

is 1.29 g/cm³. The

sedimentation coefficient The sedimentation coefficient () of a particle characterizes its sedimentation during centrifugation. It is defined as the ratio of a particle's sedimentation velocity to the applied acceleration causing the sedimentation. : s = \frac The sedime ...

is 170–187

svedberg 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 (i.e. how fast a ...

(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'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology an ...

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

alkaline In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a base (chemistry), basic, ionic compound, ionic salt (chemistry), salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as ...

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 these 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—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be c ...

, or

chloroform Chloroform, or trichloromethane, is an organic compound with chemical formula, formula Carbon, CHydrogen, HChlorine, Cl3 and a common organic solvent. It is a colorless, strong-smelling, dense liquid produced on a large scale as a precursor to ...

. The

infectivity In epidemiology, infectivity is the ability of a pathogen to establish an infection. More specifically, infectivity is a pathogen's capacity for horizontal transmission — that is, how frequently it spreads among hosts that are not in a parent� ...

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

Genome

The

genome In the fields of molecular biology and genetics, 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 ge ...

is not segmented and contains a single molecule of linear

positive-sense In molecular biology and genetics, the sense of a nucleic acid molecule, particularly of a strand of DNA or RNA, refers to the nature of the roles of the strand and its complement in specifying a sequence of amino acids. Depending on the context ...

, ss

RNA Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...

. 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. The complete genome is 7450

nucleotides Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules w ...

long. The genome has a

guanine Guanine () ( symbol G or Gua) is one of the four main nucleobases 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 is called ...

cytosine Cytosine () ( symbol C or Cyt) is one of the four nucleobases 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 attached (an am ...

content of 49.3–50.1 %. The 5' end of the genome has a usually genome-linked protein (

VPg VPg (viral protein genome-linked) is a protein that is covalently attached to the 5′ end of positive strand viral RNA and acts as a primer during RNA synthesis in a variety of virus families including Picornaviridae, Potyviridae and Caliciviri ...

), or

methylated In the chemical sciences, methylation denotes the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These ...

nucleotide cap (in the case of

Hepatitis E virus The hepatitis E virus (HEV) is the causative agent of hepatitis E. It is of the species ''Orthohepevirus A.'' Globally, approximately 939 million corresponding to 1 in 8 individuals have ever experienced HEV infection. About 15–110 million ind ...

). 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 A viral structural protein is a viral protein that is a structural component of the mature virus. Examples include the SARS coronavirus 3a and 7a accessory proteins. Bacteriophage T4 structural proteins During assembly of the bacteriophage (pha ...

. 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 of a chemical compound is defined as the mass of a sample of that compound divided by the amount of substance which is the number of moles in that sample, measured in moles. The molar mass is a bulk, not molecular, p ...

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

Antigenicity

Cross-reactivity Cross-reactivity, in a general sense, is the reactivity of an observed agent which initiates reactions outside the main reaction expected. This has implications for any kind of test or assay, including diagnostic tests in medicine, and can be a ...

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 cells are classified together based on their surface antigens, allowing the epi ...

, 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