Megalocytivirus

from Wikipedia, the free encyclopedia
Megalocytivirus
Systematics
Classification : Viruses
Area : Varidnaviria
Empire : Bamfordvirae
Phylum : Nucleocytoviricota
Class : Megaviricetes
Order : Pimascovirales
Family : Iridoviridae
Subfamily : Alphairidovirinae
Genre : Megalocytivirus
Taxonomic characteristics
Genome : dsDNA linear
Baltimore : Group 1
Symmetry : icosahedral
Cover : available
Scientific name
Megalocytivirus
Left
NCBI  Taxonomy: 308906
ViralZone ( ExPASy , SIB): 584

Megalocytivirus is a genus of giant viruses ( Nucleocytoviricota , NCLDVs) from the family of Iridoviridae , subfamily Alphairidovirinae . Like the other two genera Lymphocystivirus and Ranavirus of the Alphairidovirinae subfamily, viruses of the Megalocytivirus genus canalsoinfect real bony fish (Teleostei).

The megalocytiviruses, like the ranaviruses, are a group of closely related dsDNA viruses whose importance is increasing. They cause systemic disease in a wide variety of wild and cultivated freshwater and saltwater fish. As with Ranaviren are Megalocytivirus breakouts in aquaculture is of considerable economic importance, since animal diseases can cause significant loss or even mass deaths of farmed fish.

Infection with these viruses produces a characteristic appearance of enlarged basophilic cells ( which can be stained with basic dyes in the histological section ) in the infected organs.

construction

The virus particles (virions) of the megalocytiviruses are icosahedral in shape with a diameter of 150 to 250  nm . The genome is unsegmented and consists of double-stranded linear DNA .

Propagation cycle

Megaloviruses are believed to replicate in the same way as other iridoviruses: they attach to receptors on the host cell and thereby enter the cell via endocytosis . Uncoated virus particles then migrate into the host's cell nucleus , where a DNA polymerase encoded by the virus genome brings about DNA replication. The virus DNA then leaves the nucleus and the second stage of DNA replication in the cytoplasm begins , with DNA concatemers being formed. The concatameric viral DNA is then packaged into infectious virions. As in other Iridoviridae, the genome of Ranavirus has terminally redundant DNA

Because of the economic importance of commercial fishing and aquaculture, significant efforts have been made to understand the transmission and epizoology of megalocytiviruses.

Megalocytivirus is thought to be transmitted when an unsuspecting fish ingests tissue from infected fish or contaminated water.

It is believed that trade in larvae fish in Korea and Japan could promote the spread of the virus. Another possible mechanism for the unintentional movement of infected fish is the international trade in ornamental or aquarium fish, which includes the global trade in around 5,000 freshwater and 1,450 saltwater fish.

Clinical picture

Since megalocytiviruses were only identified and described relatively recently, the pathogenesis of megalocytivirus infection is still relatively poorly understood. The clinical symptoms associated with infection are nonspecific and can include loss of appetite, uncoordinated swimming, lethargy , gas, skin discoloration, petechiae , fin erosion, and ultimately death.

The histopathological examination of diseased tissue reveals large hypertrophied cells after which the genus is named. These usually occur in several organs, especially the kidneys, spleen and gastrointestinal tract, and less often in the liver, gills, heart or connective tissue. The hypertrophied cells are often distributed perivascularly and are greatly enlarged due to the large granular to foamy basophilic cytoplasmic inclusion bodies. When the inflated cells occlude the vasculature, focal areas of ischemic necrosis can occur in various organs .

Some researchers have suggested that the hypertrophied cells are a type of leukocyte, which matches their distribution in the tissue.

Systematics

The internal system of the genus Megalocytivirus as of February 2019 according to ICTV is as follows:

  • Genus: Megalocytivirus

There are also the following as yet unclassified candidates:

  • " European chub iridovirus " (ECIV)
  • " Giant seaperch iridovirus " (GSIV-K1)
  • " Orange-spotted grouper iridovirus " (OSGIV, " Epinephelus coioides iridovirus ")
  • " Red sea bream iridovirus " (RSIV)
  • " Rock bream iridovirus " (RBIV)
  • " South American cichlid iridovirus " (SACIV)
  • " Turbot reddish body iridovirus " (TRBIV)
  • " Three spot gourami iridovirus " (TSGIV)

Song et al. (2008) studied 48 Asian and Australian Megalocytivirus isolates in terms of their geographical location and genetic variation in the main capsid protein gene ( english major capsid protein gene ) and developed a pedigree that the 48 isolates based different on genotype into three clusters divided. One of these clusters (genotype I) is widespread in several Asian countries, including 13 isolates from Korea, nine isolates from Japan, one from Thailand, one from China and one from the South China Sea. In contrast, the other two genotypes had a smaller host range and were locally distributed. Genotype II megalocytiviruses infected freshwater fish from Southeast Asia and Australia, while genotype III megalocytiviruses mainly infected flatfish in China and Korea.

Individual evidence

  1. ↑ a b c d e ICTV: ICTV Taxonomy history: Frog virus 3 , EC 51, Berlin, Germany, July 2019; Email ratification March 2020 (MSL # 35)
  2. ↑ a b ICTV : Iridoviridae ( en )
  3. ↑ a b c d e f RJ Whittington, JA Becker, MM Dennis: Iridovirus infections in finfish - critical review with emphasis on ranaviruses . In: Journal of Fish Diseases . 33, No. 2, 2010, pp. 95-122. doi : 10.1111 / j.1365-2761.2009.01110.x . PMID 20050967 .
  4. ↑ a b c Yanong RPE, Waltzek TB: Megalocytivirus infections in fish, with emphasis on ornamental species , in: University of Florida Institute of Food and Agricultural Sciences Extension ( FA182 ) pp. 1-7, 2010
  5. ↑ a b JY Song, S Kitamura, SJ Jung, T Miyadai, S Tanaka, Y Fukuda, SR Kim, MJ Oh: Genetic variation and geographic distribution of megalocytiviruses . In: Journal of microbiology (Seoul, Korea) . 46, No. 1, 2008, pp. 29-33. doi : 10.1007 / s12275-007-0184-6 . PMID 18337689 .
  6. ↑ Eaton HE, Ring BA, Brunetti CR: The genomic diversity and phylogenetic relationship in the family Iridoviridae , in: Viruses. 2, 2010, pp. 1458-1475.
  7. ↑ a b c R Goorha: Frog virus 3 DNA replication occurs in two stages . In: Journal of Virology . 43, No. 2, 1982, pp. 519-528. PMID 7109033 . PMC 256155 (free full text).
  8. ↑ Chinchar VG, Essbauer S, He JG, Hyatt A, Miyazaki T, Seligy V, Williams T: Family Iridoviridae pp. 145–162, in: Fauquet CM, Mayo MA, Maniloff J, Desselburger U, Ball LA (eds.) : Virus Taxonomy, Eighth report of the International Committee on Taxonomy of Viruses, Academic Press, San Diego, USA 2005
  9. Jump up ↑ NS Lee, JW Do, JW Park, YC Kim: Characterization of virus distribution in Rock Bream (Oplegnathus fasciatus; Temminck and Schlegel) infected with megalocytivirus . In: Journal of Comparative Pathology . 141, No. 1, 2009, pp. 63-9. doi : 10.1016 / j.jcpa.2009.03.008 . PMID 19477463 .
  10. ↑ ICTV: ICTV Taxonomy history: Bohle iridovirus , on: ICTVonline from June 18, 2018 (ZIP)
  11. ↑ Maya A. Halaly, Kuttichantran Subramaniam, Samantha A. Koda, Vsevolod L. Popov, David Stone, KeithWay, Thomas B. Waltzek: Characterization of a Novel Megalocytivirus Isolated from European Chub ( Squalius cephalus ) , in: MDPI - Viruses 2019, 11, 440; doi: 10.3390 / v11050440 , PDF
  12. ↑ NCBI: European chub iridovirus (species)
  13. ↑ NCBI: Giant seaperch iridovirus (species)
  14. ↑ NCBI: Orange-spotted grouper iridovirus (species)
  15. ↑ CABI: red sea bream iridoviral disease
  16. ^ The Fish Site: Red Sea Bream Iridoviral Disease
  17. ↑ NCBI: Rock bream iridovirus (species)
  18. ↑ NCBI: South American cichlid iridovirus (species)
  19. ↑ Qingli Zhang, Chenyin Shi, Jie Huang, Kuntong Jia, Xinhua Chen, Hong Liuc: Rapid diagnosis of turbot reddish body iridovirus in turbot using the loop-mediated isothermal amplification method , in: Journal of Virological Methods, Volume 158, Issues 1– 2, June 2009, pp. 18-23, doi: 10.1016 / j.jviromet.2009.01.008
  20. ↑ UniProt: Proteomes - Turbot reddish body iridovirus
  21. ↑ NCBI: Three spot gourami iridovirus (species)

Web links