Varicellovirus

Varicellovirus (var′i-sel′ō-vi′rŭs) is a genus of viruses belonging to subfamily Alphaherpesvirinae, a member of family Herpesviridae. Humans and mammals serve as natural hosts. There are currently 17 species in this genus including the type species Human alphaherpesvirus 3 also known as Varicella zoster virus (VZV). Diseases associated with this genus include: HHV-3—chickenpox (varicella) and shingles; BoHV-1—infectious bovine rhinotracheitis/infectious pustular vulvovaginitis (IPV); SuHV-1 (also known as pseudorabies virus)—Aujesky's disease characterized by central nervous system signs (hindleg paralysis, meningoencephalitis), high mortality rates in young animals, and respiratory illness in older pigs.[2][3]

Varicellovirus
Virus classification
(unranked): Virus
Phylum: incertae sedis
Class: incertae sedis
Order: Herpesvirales
Family: Herpesviridae
Subfamily: Alphaherpesvirinae
Genus: Varicellovirus
Type species
Human alphaherpesvirus 3
Species[1]

See text

Species

The genus consists of the following 17 species:

Structure

As with other alphaherpesviruses, the virus particle has a layered structure: Virions consist of an envelope, a tegument, a nucleocapsid, and a core. Tegument is disordered; they do not display a structure and proteins in variable amounts are arranged sometimes in an asymmetric layer located between envelope and capsid. The viral capsid is contained within a spherical envelope which is 120–200 nm in diameter. Surface projections on envelope (viral receptors) are densely dispersed and contain small spikes that evenly dot the surface.

The capsid/nucleocapsid is round with triangulation number T=16 and exhibits icosahedral symmetry. The capsid is isometric and has a diameter of 100–110 nm.[2] The capsid consists of 162 capsomer proteins with a hexagonal base and a hole running halfway down the long axis. The core consists of a fibrillar spool on which the DNA is wrapped. The end of the fibers are anchored to the underside of the capsid shell.[4] It is a double-stranded enveloped DNA virus

GenusStructureSymmetryCapsidGenomic arrangementGenomic segmentation
VaricellovirusSpherical PleomorphicT=16EnvelopedLinearMonopartite

Life cycle

Viral replication is nuclear, and is lysogenic. Entry into the host cell is achieved by attachment of the viral glycoproteins to host receptors, which mediates endocytosis. Replication follows the dsDNA bidirectional replication model. DNA-templated transcription, with some alternative splicing mechanism is the method of transcription. The virus exits the host cell by nuclear egress, and budding.[2] Humans and mammals serve as the natural host.[2] Only one member of the Varicellovirus genus, Varicella zoster virus (HHV-3) infects Homo sapiens (humans).[5]

GenusHost detailsTissue tropismEntry detailsRelease detailsReplication siteAssembly siteTransmission
VaricellovirusMammalsEpithelial mucosaGlycoprotiensBuddingNucleusNucleusAerosol

References
  1. "Virus Taxonomy". International Committee on the Taxonomy of Viruses. Retrieved 8 January 2019.
  2. "Viral Zone". ExPASy. Retrieved 15 June 2015.
  3. ICTV. "Virus Taxonomy: 2014 Release". Retrieved 15 June 2015.
  4. ICTVdB—The Universal Virus Database, version 4. https://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/
  5. Davison AJ (2002). "Evolution of the herpesviruses". Vet. Microbiol. 86 (1–2): 69–88. doi:10.1016/s0378-1135(01)00492-8. PMID 11888691.

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