Aims:
The aim of the study is to assess whether ranaviruses isolated from fish and frogs are a threat to farmed or wild fish or amphibians. The study is carried out by doing experimental infections across species’ boundaries using viral strains isolated from different fish and amphibian species. The project studies the genetic relationships between different viral strains and new methods are produced for the differential diagnostics of these strains. One of the ranavirus strains studied within the project was isolated from European pike-perch in Finland.
Members of the genus Ranavirus belong to the virusfamily of Iridoviridae and cause mortality in fish, reptiles and amphibians in different parts of the world. Ranaviruses have been isolated in disease outbreaks of fish and amphibians in Australia, Europe, Asia and America. The Australian Epizootic Haematopoietic Necrosis (EHN) virus causes high mortality in redfinperch and rainbow trout. The ranaviruses cause mortality in catfish and sheatfish in Italy and Germany. Observations of ranaviruses in Finland have been: a ranavirus closely related to EHN virus in symptom free European pike-perch fry in 1995, and the sheatfish virus imported to Finland from Germany in 2002.
The study will assess the pathogenicity of ranaviruses when transferred to a new host species. The ranavirus strains in the project have been isolated in Europe, Asia and Australia from both fish and amphibians. The infection experiments are carried out in several different species of fish and amphibians. Mainly farmed European food fish are being studied, but perch, European pike-perch and pike are also included. Ornamental fish, the farming and trade of which has increased in Europe, are also studied as fish of exotic origin might function as virus vectors in Europe.
Experimental infections are performed in reference laboratories on fish virus diseases in Great Britain, Italy, Germany and Denmark. Evira’s task in the project is primarily to develop methods by which viruses pathogenic in different species can be separated from each other, and from harmless viruses. The differentiation methods are used on ranaviruses isolated in the experimental infections and the possible effect of the host species on the genetic variability of the viral strain is assessed.
Results:
Infection experiments on fish and amphibians are being carried out at different research institutes. Different genomic regions of the project ranaviruses has been assessed at Evira, comparisons of gene sequences have been made and differentiation methods based on these results have been produced in order to recognise different viral strains. Studies on genetic stability of ranavirus strains isolated in the infection experiments are being carried out.
Keywords:
viruses, fish viruses, iridovirus, ranavirus, fish diseases
Responsible project leader:
Ariel, Ellen, Dr., National Veterinary Institute, Aarhus, Denmark
Person at Evira responsible for the project:
Tapiovaara, Hannele, Senior Researcher, Evira, Veterinary Virology Research Unit
Contacts at Evira:
Tapiovaara, Hannele, Senior Researcher, Veterinary Virology Research Unit;
Holopainen, Riikka, Researcher, Veterinary Virology Research Unit
In cooperation with:
Barry Hill, Centre for Environment, Fisheries and Aquaculture Science (CEFAS) Weymouth Laboratory, UK;
Giuseppe Bovo, Istituto Zooprofilattico Sperimentale delle Venezie (IZSVE), Fish Pathology Department, Viale Dell'universita,Legnaro, Italy;
Tomas Vesely, Veterinary Research Institute (VRI), Brno, Czech Republic;
Sven Bergman, Friedrich-Loeffler-Institute, Federal Research Institute for Animal Health (FLI), Riems, Germany
Project status:
Previous
Year of commencement:
2005
Year of completion:
2012
Publications:
Holopainen, R.
Ranaviruses: Detection, differentiation and host immune response.
University of Helsinki, Faculty of Veterinary Medicine, Department of Veterinary Biosciences.
Doctoral thesis.
Holopainen, R., Tapiovaara, H., Honkanen, J.
Expression analysis of immune response genes in fish epithelial cells following ranavirus infection.
Fish and Shellfish Immunology 2012: Vol. 32, No. 6, pp. 1095-1105.
Bang Jensen, B., Holopainen, R., Tapiovaara, H., Ariel, E. Susceptibility of pike-perch Sander lucioperca to a panel of ranavirus isolates. Aquaculture 2011: 313, pp. 24-30.
Holopainen, R., Honkanen, J., Jensen Bang, B., Ariel, E., Tapiovaara, H. Quantitation of ranaviruses in cell culture and tissue samples. Journal of Virological Methods 2011: 171, pp. 225-233.
Ohlemeyer, S., Holopainen, R., Tapiovaara, H., Bergmann, S.M., Schütze, H. Major capsid protein gene sequence analysis of the Santee-Cooper ranaviruses DFV, GV6, and LMBV. Diseases of Aquatic Organisms 2011: 96, pp. 195-207.
Ariel E, Holopainen R, Olesen NJ, Tapiovaara H. Comparative study of ranavirus isolates from cod (Gadus morhua) ans turbot (Psetta maxima) with reference to other ranaviruses. Archives of Virology 155: 1261-1271, 2010.
Ariel E, Kielgast J, Svart HE, Larsen K, Tapiovaara H, Bang Jensen B, Holopainen R Ranavirus in wild edible frogs Pelophylax kl. esculentus in Denmark Dis Aquat Org 85:7-14, 2009.
Holopainen R, Ohlemeyer S, Schütze H, Bergmann SM, Tapiovaara H: Ranavirus phylogeny and differentiation based on major capsid protein, DNA polymerase and neurofilament triplet H1-like protein gene. Dis Aquat Org 85:81-91, 2009.
Ariel E, Nicolajsen N, Christoffersen M-B, Holopainen R, Tapiovaara H, Jensen B: Propagation and isolation of ranaviruses in cell culture. Propagation and isolation of ranaviruses in cell culture. Aquaculture 294:159-164, 2009.
Holopainen R, Tapiovaara H: New and emerging systemic iridoviral diseases of European fish and aquatic ecosystems. Virologipäivät, Oulu, 2007 Holopainen R, Stumpf P, Bergmann S, Tapiovaara H: Molecular detection and phylogeny of ranaviruses, 7th International symposium on viruses of lower vertebrates, Oslo, 2007
Project is financed by:
The EU Commission (EU’s Sixth Framework programme for Research and Technological Development, EU agreement number SSPE-CT-2005-006);
the institutions taking part in the project
Evira's project code:
8403