White Spot Syndrome Virus

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White Spot Syndrome Virus
Systematics
Classification : Viruses
without rank: "Baculo-like viruses" ?
Family : Nimaviridae
Genre : Whispovirus
Type : White Spot Syndrome Virus
Taxonomic characteristics
Genome : dsDNA circular
Baltimore : Group 1
Symmetry : helical
Cover : available
Scientific name
White spot syndrome virus
Short name
WSSV
Left
NCBI  Taxonomy: 342409
ViralZone ( ExPASy , SIB): 144 (family) ,
541 (genus)
ICTV Taxon History: 201853922

The white spot syndrome virus ( scientifically white spot syndrome virus , WSSV , also Chinese baculovirus-like virus , CBV ) is the only species (and type species) of the genus Whispovirus ( whi te spo t virus ) confirmed by the International Committee on Taxonomy of Viruses (ICTV) ), the only genus in the Nimaviridae family . It is for the emergence of white spot syndrome ( english White spot syndrome , WSS) in a variety of crustaceans , especially Penaeidae ( Dendrobranchiata , decapods ), responsible. The disease is contagious and usually fatal, and it kills the shrimp quickly. Outbreaks of this disease have wiped out the entire population of many shrimp farms around the world in a matter of days.

WSSV was previously placed in the Baculoviridae family or directly in the Baculovirus genus , but has now been separated from the ICTV as an independent family. In addition to WSSV, a number of other viruses related to it can occur as the causative agent of the white spot syndrome WSS. They form a group that is also known as the white spot baculovirus complex ( English Whitespot Syndrome Baculovirus complex (WSBV)).

Spread history

The first reported epidemic due to this virus came from Taiwan in 1992 . The following year, in 1993 reports came about losses due to white spot syndrome from China (mainland) where it practically to a collapse of the shrimp farming came. In the same year, outbreaks followed in Japan and Korea , and in 1994 in Thailand , India and Malaysia . In 1996 all of East and South Asia were badly affected. At the end of 1995 there were reports from the United States , 1998 from Central and South America , 1999 from Mexico and 2000 from the Philippines , and 2011 from Saudi Arabia . Finally, the virus was discovered in Queensland , Australia in November 2016 . It is believed that Australia was the last region where shrimp could still grow free of the virus.

construction

The virions (virus particles) of WSSV are rod-shaped to ovoid (egg-shaped) with a diameter of 70-195  nm and a length of 240-380 nm. The nucleocapsid core has a diameter of 95-165 nm and a length of 120-205 nm. The virions have an outer membrane envelope made of a lipid bilayer, sometimes with a tail-like appendix at one end of the virion. The nucleocapsid consists of 15 vertical helices that are located along the longitudinal axis. Each helix has two parallel strips made up of 14 globular capsomeres , each 8 nm in diameter.

Genome

WSSV is a double-stranded DNA virus (dsDNA virus) and is therefore a member of Group I of the Baltimore classification . The genome is unsegmented (monopartite) and circular (ring-shaped) with a length of 292,967  bp . It encodes putative 531 open reading frames ( English open reading frames , ORFs). One of the encoded proteins , WSSV449, bears a certain similarity to the host protein Tube and can function like Tube by activating the NF-κB signaling pathway.

Systematics

Internal system of the family

As of March 2019, there is only one genus in the Nimaviridae family confirmed by the International Committee on Taxonomy of Viruses (ICTV), namely Whispovirus , and in this only one confirmed species, the White spot syndrome virus (WSSV). The National Center for Biotechnology Information (NCBI) lists the following ICTV-confirmed and putative subgroups and family members:

  • Family: Nimaviridae
  • Genus: Whispovirus
  • Species: White spot syndrome virus (WSSV, obsolete: White spot syndrome baculovirus )
  • Penaeus monodon nonoccluded baculovirus III
  • Shrimp white spot syndrome virus, plus isolate Tongan
  • unclassified members of the Whispovirus family :
  • 'Metopaulias depressus WSSV-like virus'
  • 'Procambarus clarkii virus'
  • unclassified members of the family Nimaviridae :
  • 'Hemigrapsus takanoi nimavirus'
  • 'Marsupenaeus japonicus endogenous nimavirus'
  • 'Metapenaeus ensis nimavirus'
  • 'Penaeus monodon endogenous nimavirus'
  • 'Sesarmops intermedium nimavirus'

In the literature, at least three viruses have been identified as causing white spot syndrome ( English White Spot Syndrome , WSS) and thus as members of the white spot baculovirus complex (WSBV, also known as China virus complex ). They appear to be very similar viruses. In detail these are:

  • Chinese hypodermal hematopoietic necrosis baculovirus ( hypodermal hematopoietic necrosis baculovirus , HHNBV) - causes Shrimp Explosive Epidermic Disease (SEED)
  • Japanese rod-shaped nuclear virus (RV-PJ) - affects Peneus japonicus
  • Thai systemic ectodermal and mesodermal baculovirus ( systemic ectodermal and mesodermal baculovirus , SEMBV) caused the red diease and white spot syndrome monodon Penaeus

Due to the separation of the Nimavridae from the Baculoviridae , this complex probably consists of members or candidates of the Nimaviridae .

External system of the family

The Nimaviridae evidently form an as yet unnamed family group with the Baculoviridae , Hytrosaviridae , Nudiviridae and the genus Bracovirus of the supposed polyphyletic Polydnaviridae , for which Koonin et al. (2015 and 2019) the following family tree was proposed:



Nimaviridae


   

Hytrosaviridae


   

Baculoviridae


   

Nudiviridae


   

Polydnaviridae : Bracovirus




Template: Klade / Maintenance / 3

Template: Klade / Maintenance / Style

Apparently the members of the white-spot baculovirus complex are all within this kin group. The term “Baculo-like viruses” (only including Baculoviridae and Nudiviridae ) used in the narrow sense by the Swiss Institute for Bioinformatics ( SIB ) therefore seems to be used by some authors in a broader sense for this entire group.

Propagation cycle

The replication of the virus particles takes place in the cell nucleus (nuclear). The transcription uses the virus DNA as a template.

The virus infects an unusually large number of crustaceans. The virus is mainly transmitted by ingestion via the water (horizontal transmission) and from infected mother shrimp (vertical transmission) in shrimp farms and crab hatcheries. The virus is also found in wild shrimp populations, particularly in the coastal waters bordering shrimp farms in Asian countries. However, no mass mortals were observed in the wild shrimp.

pathology

In the host, WSSV attacks a large number of cells of ectodermal and mesodermal origin. Histological changes in gill epithelium , in the antenna gland , in the hematopoietic tissue ( english Hematopoietic tissue ) in the nerve tissue , the tissue can be observed and in the intestinal epithelial tissue. Infected cells show conspicuous intranuclear occlusions , are initially eosinophilic , but can be stained basophilically with increasing age . They have hypertrophied nuclei with a chromatin border and cytoplasmic clearing . The pathogenesis (course of the disease) involves spreading tissue necrosis and decay.

White spots on the shell of infected shrimp appear under the scanning electron microscope as large, dome-shaped spots on the shell, 0.3-3.0 mm in diameter. Smaller white spots of 0.02 to 0.10 mm appear as connected spheres on the surface of the cuticle. The chemical composition of the spots is similar to that of the carapace, with calcium accounting for 80-90% of the total material and possibly due to anomalies in the cuticle epidermis.

After infection with this virus, several biochemical changes can be observed: The glucose consumption and the lactate concentration in the cytoplasm increase, the activity of glucose-6-phosphate dehydrogenase increases and the triglyceride concentration decreases. The potential- dependent anion channel of the mitochondria is also upregulated.

diagnosis

The infection with WSSV differs in the described histological findings from other described Penaeid infections, for example due to the yellowhead virus (YHV) and the Decapod penstyldensovirus 1 (alias Infectious hypodermal and hematopoietic necrosis virus , IHHNV), since YHV has a reduced tissue specificity and only infects the intestinal epithelial tissue, and IHHNV causes intranuclear occlusions which can be stained eosinophilically, but which does not change in the course of the infection with this virus.

A quick and specific diagnosis of the virus can be carried out by nested -PCR or quantitative PCR .

therapy

There are no known treatments for WSS.

prevention

A large number of disinfectants are commonly used in shrimp farms and hatcheries to help prevent an outbreak of WSS. Storage of uninfected shrimp seeds and careful keeping away from environmental pollution to avoid contamination are useful management measures. Site selection is possibly one of the most important factors in preventing WSS. Shrimp that were raised in areas with relatively low temperature fluctuations and at water temperatures of more than 29 ° C showed an increased resistance to WSSV.

Individual evidence

  1. ↑ a b c Whitespot Syndrome Baculovirus complex (WSBV) . Gulf States Marine Fisheries Commission. 2003. Archived from the original on October 18, 2005. Retrieved June 30, 2005.
  2. ↑ Roxane-Marie Barthélémy, Eric Faure, Taichiro Goto: Serendipitous Discovery in a Marine Invertebrate (Phylum Chaetognatha) of the Longest Giant Viruses Reported till Date , in: Biology 2019, Abstract
  3. ↑ a b c Viral Zone . ExPASy. Retrieved September 5, 2019.
  4. ↑ a b ICTV : ICTV Master Species List 2018b.v2 MSL # 34v, March 2019
  5. ↑ Lightner, Donald V .: A handbook of shrimp pathology and diagnostic procedures for diseases of cultured penaeid shrimp . World Aquaculture Society, Baton Rouge, Louisiana, USA, 1996.
  6. ↑ W.-B. Zhan, Y.-H. Wang, JL Fryer, K.-K. Yu, H. Fukuda, Q.-M. Meng: White spot syndrome virus infection of cultured shrimp in China . In: J. Aquat. Anim. Health, Vol. 10, 1998, pp. 405-410, Cefas Abstract
  7. ↑ Chen, SN: Current status of shrimp aquaculture in Taiwan. . In: CL Browdy, JS Hopkins (Eds.): Swimming through troubled water . Proceedings of the special session on shrimp farming. Aquaculture '95. World Aquaculture Society, Baton Rouge, Louisiana, USA, 1995, pp. 29-34.
  8. ↑ J. Huang, J., XL Song, J. Yu, CH Yang et al .: Baculoviral hypodermal and hematopoietic necrosis: study on the pathogen and pathology of the explosive epidemic disease of shrimp . In: Marine Fisheries Research . 16, 1995, pp. 1-10.
  9. ↑ White Spot Detected on Queensland Prawn Farm . December 2, 2016. Retrieved December 8, 2016.
  10. ↑ a b E. CB Nadala Jr., LM Tapay, PC Loh et al .: Characterization of a non-occluded baculovirus-like agent pathogenic to penaeid shrimp . In: Diseases of Aquatic Organisms . 33, No. 3, 1998, pp. 221-229. doi : 10.3354 / dao033221 . PMID 9745719 .
  11. ↑ MCW Van Hulten, J. Witteveldt, S. Peters, N. Kloosterboer, R. Tarchini, F. Fiers, H. Sandbrink, RK Lankhorst, JM Vlak et al .: The white spot syndrome virus DNA genome sequence . In: Virology . 286, No. 1, 2001, pp. 7-22. doi : 10.1006 / viro.2001.1002 . PMID 11448154 .
  12. ↑ PH Wang, ZH Gu, DH Wan, MY Zhang, SP Weng, XQ Yu, JG He: The shrimp NF-κB pathway is activated by white spot syndrome virus (WSSV) 449 to facilitate the expression of WSSV069 (ie1), WSSV303 and WSSV371 . In: PLoS ONE . 6, No. 9, 2011, p. E24773. doi : 10.1371 / journal.pone.0024773 . PMID 21931849 . PMC 3171479 (free full text).
  13. ↑ NCBI: Nimaviridae
  14. ↑ SiB: Nimaviridae , on: ViralZone
  15. ^ Dupuy C, Huguet E, Drezen JM: Unfolding the evolutionary story of polydnaviruses . In: Virus Res . 117, No. 1, 2006, pp. 81-89. doi : 10.1016 / j.virusres.2006.01.001 . PMID 16460826 .
  16. ↑ Eugene V. Koonin, Natalya Yutin: Evolution of the Large Nucleocytoplasmatic DNA Viruses of Eukaryotes and Convergent Origins of Viral Gigantism , in: Advances in Virus research, Volume 103, AP January 21, 2019, doi: 10.1016 / bs.aivir.2018.09 .002 , pp. 167-202
  17. ^ Eugene V. Koonin, Valerian V. Dolja, Mart Krupovic: Origins and evolution of viruses of eukaryotes: The ultimate modularity , in: Virology from May 2015; 479-480. 2-25, Epub March 12, 2015, PMC 5898234 (free full text), PMID 25771806
  18. ↑ SIB: Double Strand DNA Viruses , on: ViralZone
  19. ↑ Michael Wolfinger: Diseases in crayfish - aquaculture , white spot disease (WSSV - White Spot Syndrome Virus)
  20. ↑ a b C. Wongteerasupaya, C., JE Vickers, S. Sriurairatana, GL Nash, A. Akarajamorn, V. Boonseang, S. Panyin, A. Tassanakajon, B. Withyachumnarnkul, TW Flegel et al .: A non-occluded , systemic baculovirus that occurs in cells of ectodermal and mesodermal origin and causes high mortality in the black tiger prawn Penaeus monodon . In: Diseases of Aquatic Organisms . 21, 1995, pp. 69-77. doi : 10.3354 / dao021069 .
  21. ↑ CS Wang, KF Tang, GH Kou, SN Chen et al .: Light and electron microscopic evidence of white spot disease in the giant tiger shrimp, Penaeus monodon (Fabricius), and the kuruma shrimp, Penaeus japonicus (Bate), cultured in Taiwan . In: Journal of fish Diseases . 20, No. 5, 1997, pp. 323-331. doi : 10.1046 / j.1365-2761.1997.00301.x .
  22. ↑ Chen IT, Aoki T, Huang YT, Hirono I, Chen TC, Huang JY, Chang GD, Lo CF, Wang KC: White spot syndrome virus induces metabolic changes resembling the Warburg effect in shrimp hemocytes in the early stage of infection. in: J Virol, 2011
  23. ↑ ICTV: Decapod penstyldensovirus 1 Taxonomy history
  24. ↑ NCBI: Decapod penstyldensovirus 1 syn. Infectious hypodermal and h [a] ematopoietic necrosis virus, acronym IHHNV
  25. ↑ A. K Dhar, MM Roux, KR Klimpel et al .: Detection and Quantification of Infectious Hypodermal and Hematopoietic Necrosis Virus and White Spot Virus in Shrimp Using Real-Time Quantitative PCR and SYBR Green Chemistry . In: Journal of Clinical Microbiology . 39, No. 8, 2001, pp. 2835-2845. doi : 10.1128 / JCM.39.8.2835-2845.2001 . PMID 11474000 . PMC 88247 (free full text).
  26. ↑ S. Kakoolaki, I. Sharifpour, M. Afsharnasab, A. Sepahdari, MR Mehrabi, B. Ghaednia, Hb Nezamabadi: Effects of temperature on hematological and histopathological changes and survival rate of juvenile Fenneropenaeus vannamei experimentally challenged to White Spot Virus . In: Iranian Journal of Fisheries Sciences . 13, No. 1, 2014, pp. 91-102.

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