Cyvirus cyprinidallo2

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Cyvirus cyprinidallo2
Virus classification OOjs UI icon edit-ltr.svg
(unranked): Virus
Realm: Duplodnaviria
Kingdom: Heunggongvirae
Phylum: Peploviricota
Class: Herviviricetes
Order: Herpesvirales
Family: Alloherpesviridae
Genus: Cyvirus
Species:
Cyvirus cyprinidallo2
Synonyms
  • Cyprinid herpesvirus 2
  • CyHV-2

Cyvirus cyprinidallo2, also known as Cyprinid herpesvirus 2 (CyHV-2) is a species of virus in the genus Cyprinivirus , family Alloherpesviridae , and order Herpesvirales . [1]

Contents

CyHV2 can also be classified as herpesviral hematopoietic necrosis virus (HVHN) and infects goldfish (Carassius auratus) of all ages. [2] [3] It can also infect the closely related species, Prussian Carp (C. gibelio) however koi and goldfish hybrids cannot be infected by CyHV2. [2] Outbreaks have been reported in both cultured and wild populations, and are highly lethal. [2]

Background

Jung and Miyazaki (1995) were the first to describe CyHV2 in Japan. [2] [4] This was achieved via isolation from moribund goldfish after the epizootic disease was observed in 1992 and 1993. [4] Culture of HVHN was unsuccessful until 2007. [5]

Genome

Whole genome sequencing revealed that the CyHV2 genome is 290,304 bp in size. [3] This number may be variable due to tandem reiterations. [3] Heterogeneous genome size is often observed in other species of herpesviruses. [3] These short yet complex tandem reiterations are most often seen in the terminal direct repeats; the most prevalent being the telomere-like repeats located towards the genome ends. [3] In comparison to the other viruses, the CyHV2 genome is the most complex in terms of the unique regions plus one copy of terminal direct repeats. [3]

HVHN has approximately 154 open reading frames (ORFs) and splicing between protein-coding regions affects 9 of these ORFs. [3] Five gene families have been identified. This included multiple genes from TNFR, ORF2, ORF25, RING, and ORF153, as well as ORF22, which is present as a family of two. [3]

Pathology

External symptoms of fish impacted with CyHV2 typically show pale patches localized at the gills but do not exhibit lesions. [2] [5] Fish with this infection also appeared to be lethargic, anorexic, and exhibited a loss of appetite. [2] [5] CyHV2 is more often characterized by internal symptoms such as an enlarged kidney and spleen, as well as pallor of the kidney. [2] Histopathology of infected goldfish has revealed tissue death in the hematopoietic tissues in both the kidney and the splenic pulp. [2] Necrosis was also observed in the pancreas. [2] [4] Smaller, more scattered tissue death and swelling was also observed in the lamina propria as well as the submucosa of the intestine. [2] [4]

At this time, disease prevention is mainly achieved by avoidance. [2] A formalin-inactivated vaccine developed in 2015 was effective against goldfish infected with HVHN, however, as of now, there is not an established timeline that discusses the duration of protection. [2] [6]

References

  1. ↑ "Virus Taxonomy: 2022 Release". International Committee on Taxonomy of Viruses (ICTV). March 2023. Retrieved 16 September 2023.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 Hanson, L.; Doszpoly, A.; van Beurden, S. J.; de Oliveira Viadanna, P. H.; Waltzek, T. (2016), "Alloherpesviruses of Fish" , Aquaculture Virology, Elsevier, pp. 153–172, doi:10.1016/b978-0-12-801573-5.00009-7, ISBN   978-0-12-801573-5 , retrieved 2024-03-27
  3. 1 2 3 4 5 6 7 8 Davison, A. J.; Kurobe, T.; Gatherer, D.; Cunningham, C.; Korf, I.; Fukuda, H.; Hedrick, R. P.; Waltzek, T. B. (2013). "Comparative Genomics of Carp Herpesviruses". Journal of Virology. 87 (5): 2908–2922. doi:10.1128/JVI.03206-12. ISSN   0022-538X. PMC   3571366 . PMID   23269803.
  4. 1 2 3 4 Jung, S. J.; Miyazaki, T. (1995). "Herpesviral haematopoietic necrosis of goldfish, Carassius auratus (L.)" . Journal of Fish Diseases. 18 (3): 211–220. Bibcode:1995JFDis..18..211J. doi:10.1111/j.1365-2761.1995.tb00296.x. ISSN   0140-7775.
  5. 1 2 3 Jeffery, K. R.; Bateman, K.; Bayley, A.; Feist, S. W.; Hulland, J.; Longshaw, C.; Stone, D.; Woolford, G.; Way, K. (2007). "Isolation of a cyprinid herpesvirus 2 from goldfish, Carassius auratus (L.), in the UK" . Journal of Fish Diseases. 30 (11): 649–656. Bibcode:2007JFDis..30..649J. doi:10.1111/j.1365-2761.2007.00847.x. ISSN   0140-7775. PMID   17958608.
  6. ↑ Ito, T.; Maeno, Y. (2015). "Effect of booster shot and investigation of vaccination efficacy period against herpesviral haematopoietic necrosis (HVHN) in goldfish Carassius auratus" . Veterinary Microbiology. 175 (1): 139–144. doi:10.1016/j.vetmic.2014.11.005. PMID   25434995.
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