Ranaviruses from edible frog, cod and turbot


<p>Evira has studied ranaviruses in fish and frogs and has participated in the recently completed project funded by EU. Evira developed methods for the differentiation of ranaviruses and together with European research partners identified ranaviruses found in Europe. Ranaviruses infect fish, amphibians and reptiles. Ranaviruses are not pathogenic to humans or other mammals.</p>

Ranavirus strains found in Denmark in edible frog, cod and turbot were studied in cooperation with the Danish National Veterinary Institute (located in Århus). The amphibian virus was isolated in Denmark in the outbreak of summer 2008, which killed more than one thousand edible frogs. The ranaviruses of cod and turbot were isolated from Danish fish that manifested no symptoms. The research focused e.g. on the pathogenicity of the viruses and their genetic characteristics. The viruses found in cod and turbot did not cause mortality in rainbow trout fry in experimental conditions. The studies did reveal, however, that both viruses isolated from fish as well as the ranavirus strain isolated from edible frog are genetically closely related to pathogenic ranaviruses present in both Australia and Europe.

Ranaviruses are large DNA viruses of the Iridoviridae family and disease outbreaks caused by these viruses have been reported all over the world. Ranaviruses can cause a fatal systemic infection in both wild and cultured fish and amphibians. In individual cases the amphibian ranaviruses have been known to also infect fish, and vice versa. Several ranaviruses have been found in amphibians both in Europe and elsewhere in the world, and the viruses are believed to have contributed to the worldwide decrease in amphibian populations. One ranavirus ( Epizootic haematopoietic necrosis virus, EHNV) has infected and killed perch and rainbow trout in Australia. In Europe ranaviruses have caused mass mortality of catfish in e.g. France and Italy. In Finland ranavirus has so far been isolated only from healthy pike-perch fry.

The research outcomes have been published in international journals:
Ariel E, Holopainen R, Olesen NJ, Tapiovaara H., 2010. Comparative study of ranavirus isolates from cod (Gadus morhua) ans turbot (Psetta maxima) with reference to other ranaviruses. Archives of Virology. 155: 1261-1271.
Ariel E, Kielgast J, Svart HE, Larsen K, Tapiovaara H, Bang Jensen B, Holopainen R, 2009. Ranavirus in wild edible frogs Pelophylax kl. esculentus in Denmark. Diseases of Aquatic Organisms. 85:7-14.

Find out more about the research project   Risk assessment of new and emerging systemic iridoviral diseases for European fish and aquatic ecosystems (RANA)

For more information please contact:
Researcher Riikka Holopainen, Veterinary Virology Research Unit tel. +358 (0) 207724579, riikka.holopainen at-merkki.gif : 1Kb evira.fi
Senior Researcher Hannele Tapiovaara, Veterinary Virology Research Unit tel. +358 (0) 207724589, hannele.tapiovaara at-merkki.gif : 1Kb evira.fi

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