Proboscivirus

Proboscivirus is a genus of viruses in the order Herpesvirales, in the family Herpesviridae, in the subfamily Betaherpesvirinae. Elephants serve as natural hosts. The type species is Elephantid betaherpesvirus 1.[1] EEHV1 is apathogenic for African elephants but causes fatal haemorrhagic disease in Asian elephants.[2][3] The name "Proboscivirus" comes from the Greek word προβοσκίς or "proboscis" meaning "the elephant trunk," for which the virus accordingly uses as its means of contraction and transmission (secretions or openings of the trunk) to enter the elephant's body.

Proboscivirus
Virus classification
(unranked): Virus
Phylum: incertae sedis
Class: incertae sedis
Order: Herpesvirales
Family: Herpesviridae
Subfamily: Betaherpesvirinae
Genus: Proboscivirus
Type species
Elephantid betaherpesvirus 1
Species

See text

Taxonomy

Proboscivirus is located under the listings of the ICTV Updates as Section §2005.049-050V.04.[4] With the creation of Proboscivirus as a new genus came the creation and categorization of a new species under this genus, by the name of Elephantid betaherpesvirus 1 (Acronym: EEHV1 and Scientific Name: Elephant endotheliotropic herpesvirus)[5] under ICTV §2005.051-050V.04.

It was suggested by Pellett (2014) that the phylogenetic divergence of Proboscivirus from other genera in the subfamily Betaherpesvirinae warrants reassignment of the genus to a new subfamily that would be called Deltaherpesvirinae.[6] However, the genus remains in the Betaherpesvirinae in currently accepted ICTV taxonomy.

Species

The genus consists of the following species:

Structure

Viruses in Proboscivirus are enveloped, with icosahedral, spherical to pleomorphic, and round geometries, and T=16 symmetry. The diameter is around 150-200 nm. Genomes are linear and non-segmented.[2]

Considering Proboscivirus is a herpesvirus, it is then unique in the sense that morphologically the virus is atypical to other viruses. According to University of Glasgow Immunology & Virology Professor, A.J. Davison, and his research team, the Proboscivirus morphology is a "linear, double-stranded DNA genome of 125-290 kbp contained within a T=16 icosahedral capsid, which is surrounded by [a] proteinaceous [mixture] and lipid envelope containing membrane-associated proteins".[7] Species under the genus Proboscivirus tend to leave physical symptoms of cyanosis of the tongue, mouth/stomach ulcers, oedema of the head (or trunk for Elephants) on its host - often leading to death afterwards.[8]

GenusStructureSymmetryCapsidGenomic arrangementGenomic segmentation
ProboscivirusSpherical 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. Elephants serve as the natural host.[2]

GenusHost detailsTissue tropismEntry detailsRelease detailsReplication siteAssembly siteTransmission
ProboscivirusElephantsNoneGlycoprotiensBuddingNucleusNucleusContact

References
  1. "Virus Taxonomy: 2018b Release" (html). International Committee on Taxonomy of Viruses (ICTV). March 2019. Retrieved 10 July 2019.
  2. "Viral Zone". ExPASy. Retrieved 15 June 2015.
  3. ICTV. "Virus Taxonomy: 2014 Release". Retrieved 15 June 2015.
  4. "International Committee on Taxonomy of Viruses (ICTV)".
  5. Carstens, E.B.; Ball, L.A. (2009). "Ratification vote on taxonomic proposals to the International Committee on Taxonomy of Viruses (2008)". Virology Division News. 154 (7): 1181–8. doi:10.1007/s00705-009-0400-2. PMID 19495937.
  6. Pellett PE (2014). "Commentary: Trunkloads of Viruses". Journal of Virology. 88 (23): 13520–13522. doi:10.1128/JVI.02359-14. PMC 4248977.
  7. Pellet, P.E. Roizman (2006) The Herpesviridae: An introduction. IN: Knipe, DM; Howley, PM; Griffin, DE; Lamb, RA; Martin, MA; Roizman, B; Strauss, SE (eds). Fields Virology, 5th Edition. Lippincott, Williams & Wilkins, Philadelphia; pp 2479-2499.
  8. Schaftenaar, W.; Reid, C.; Martina, B.; Fickel, J.; Osterhaus, A. D. M. E. (2010). "Nonfatal clinical presentation of elephant endotheliotropic herpes virus discovered in a group of captive Asian elephants (Elephas maximus)". Journal of Zoo and Wildlife Medicine. 41 (4): 626–632. doi:10.1638/2009-0217.1. PMID 21370642.
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