Aims:
Infectious viral haemorrhagic septicaemia (VHS) in fish is an easily spreading disease which causes extensive fish mortality and therefore economic losses to fish farms.
- The goal of the project is to clarify how the VHS virus spreads within Finland and whether the reason for the outbreaks of the disease that have occurred in different parts of the Gulf of Finland are from a common source, that is to say, are the viral strains that have been isolated during different years from the same areas identical or are the strains different from each other.
- In the research we aimed at clarifying the genetic relationship of the VHS viral strains isolated in Finland and the epidemiology of the outbreaks by comparing the genetic make-up of the viruses between themselves and to other known VHSV strains. This is how we also could assess how closely related the VHSV strains isolated in Finland were to the viral strains isolated from wild salt water fish in the sea area and the viral strains isolated elsewhere in Europe.
- The goal of the study was to establish whether the VHS virus occurs in wild fish in the Finnish waters and to compare groups of genes in the VHS strains isolated from wild fish.
Results:
The fish farms have sent in samples from rainbow trout every second year for testing for viral diseases. On farms in the VHS restricted areas samples are taken every second year. Samples have been collected from the fish farms during 2000 - 2007. When the G and Nv genes of the virus were compared in the study it showed that the VHS viral strains that had been isolated from rainbow trout in Finland belong to genotype I and from there to group I d, to which an old isolation from Norway also belongs. The strains isolated in Finland are genetically close to the oldest Danish fresh water VHS strains (I c). Based on phylogenetic analyses, all of the strains isolated from Finnish fish farms are very similar (the genetic make-up is identical to 99.3-100 per cent), which indicates a common source of infection.
During the course of the study the VHS virus was found in the wild fish lamprey and Baltic herring.
In the spring of 2004 a more extensive study of wild fish was started in conjunction with Suomen kalatalous- ja ympäristöinstituutti (Finnish Fisheries and Environment Institute). A total of 1800 herring or 180 pools (10 fish/pool) were collected from the Finnish Archipelago. The VHS virus was found in 44 pools. In later years six positive pools were found in the Archipelago Sea and one in the Gulf of Bothnia. The study of these viral strains is currently in the final stage. A total of 7220 Baltic herring or 722 pools were studied in 2004 - 2006.
A great number of the strains isolated from wild fish have been sequenced. The Finnish VHSV strains that have been isolated from herring and lamprey are of genotype II. VHS viruses that belong to this group have been isolated previously also in the central and northern parts of the Baltic Sea. The VHSV strains in the sea area are divided into different genotypes while the strains in fresh water belong to genotype I. The most varied VHSV strains are found in salt water, these are also genotype I. This would indicate that the viruses in fresh water originate from the sea.
Keywords:
VHS virus, fish, fish farming, virus characterisation, epidemiology
Responsible project leader:
Sihvonen, Liisa, Evira's Research Director and Professor in Veterinary Virology, University of Helsinki, Department of Basic Veterinary Sciences
Person at Evira responsible for the project:
Gadd, Tuija, Senior Researcher, Veterinary Virology Research Unit
In cooperation with:
Fish necropsy and pathology: Evira’s pathology (Anna Maria Eriksson, Eija Rimaila-Pärnänen) and Evira’s Veterinary Virology (Hannele Tapiovaara, Tuija Gadd);
Cultivation of VHS viruses, immunological identification, copying of the viruses’ gene groups and analyses of the gene sequences: Evira’s Veterinary Virology (Tuija Gadd, Tiina Nokireki, Hannele Tapiovaara, Miia Jakava-Viljanen);
Serotyping of VHS strains and infection tests: In the EU fish virus reference laboratory (Ellen Ariel, Katja Einer-Jensen, Niels-Jorgen Olesen, DVL, Aarhus, Denmark);
Investigations into the epidemiology of the outbreaks: Evira’s Veterinary Virology (Tuija Gadd, Tiina Nokireki, Liisa Sihvonen)
Project status:
Previous
Year of commencement:
2010
Year of completion:
2013
Publications:
Gadd, T. Fish rhabdoviruses - Viral haemorrhagic septicaemia virus (VHSV) and perch rhabdovirus (PRV): Study of viral strains and the disease epidemiology in Finland. 2013 Diss.
Gadd, T., Jakava-Viljanen, M., Koski, P., Sihvonen, L.
Different strains of viral haemorrhagic septicaemia virus (VHSV) isolated from farmed and wild fishes in Finland.
9th International Congress of Veterinary Virology 4.-7.9.12, Madrid, Spain.
Abstract, poster
Abstract book pp. 158-159.
Gadd, T. Jakava-Viljanen, M., Tapiovaara, H., Koski, P., Sihvonen, L. Epidemiological aspects of viral haemorrhagic septicaemia virus genotype II isolated from Baltic herring, Clupea harengus membras L. Journal of Fish Diseases 2011: 34, pp. 517-529.
Gadd, T., Jakava-Viljanen, M., Einer-Jensen, K., Ariel, E., Koski, P., Sihvonen, L. Viral haemorrhagic septicaemia virus (VHSV) genotype II isolated from European river lamprey Lampetra fluviatilis in Finland during surveillance from 1999 to 2008. Diseases of aquatic organisms 2010: 88, pp. 189–198.
Raja-Halli M, Vehmas TK, Rimaila-Pärnänen E, Sainmaa S, Skall HF, Olesen NJ, Tapiovaara H, Viral haemorrhagic septicaemia (VHS) outbreaks in Finnish rainbow trout farms..Dis Aquat Org (2006), 72:201-211
Lisätietoa suomalaisista VHS – viruksista (Tuija Vehmas ja Eija Rimaila-Pärnänen). Kalankasvattaja 2/2007
VHS in Finland – description of the first cases.Fourth annual meeting of EU National Reference laboratories for fish diseases. Brussels, September 26-27, 2000 (Rimaila-Pärnänen E., Tapiovaara, H.)
Ahvenanmaan ja Pyhtään VHS-tapauksille ei löytynyt yhteistä tekijää. Suomen Kalankasvattaja 4:33-38, 2000 (Sainmaa, S., Rimaila-Pärnänen, E., Tapiovaara, H.)
Report of the first case of viral haemorrhagic septicaemia (VHS) in Finland. Report of the working group on pathology and diseases of marine organisms, Santiago de Compostela, Spain, 13-17 March 2001. ICES CM 2001/F:02, ref,: ACME+E (Rimaila-Pärnänen, E, Sainmaa S., Ek-Kommonen C., Tapiovaara H.)
Lohikalojen virusperäisen verenvuotoseptikemiadiagnostiikan kehittäminen polymeraasiketjureaktion avulla. Opinnäytetyö, Helsingin ammattikorkeakoulu, 2001 (Minna Toivanen).
VHS – virus ja sen esiintyminen Itämeressä, Tiedotustilaisuus alan toimijoille, Parainen 22.1.04 ( T. Vehmas, M. Raja-Halli)
VHS Suomessa, EAFPn kokous HKI 5.2.04 (T. Vehmas, M. Raja-Halli)
Suomen VHS-tilanne ja viruskannat. Virologipäivät, Jyväskylä 11.12.3.2004 (Raja-Halli M., Vehmas T., Tapiovaara H.).
VHS - virustutkimus, Tarttuvatautipäivät (MMMELO), HKI 12.5.05 (T. Vehmas)
VHS in Finland, EUn referenssilaboratoriokokous Århus, Tanska 21.6.05 (T. Vehmas)
VHS virus infection in Finland. Virologipäivät 2.-3.3.2006, Tampere (H. Tapiovaara)
Kalojen rhabdovirusten (VHSV ja eurooppalainen ahvenen rhabdovirus) molekyläärinen tyypittäminen ja epidemiologia, Eviran tutkimusseminaari, HKI 3.10.06 (T. Vehmas)
Rhabdoviruses – VHSV and European Perch Rhabdovirus of Fish: Molecular Characterisation and Epidemiology, Virus club, HKI 1.3.07 (T. Vehmas)
Ajankohtaista virustutkimuksista, EAFPn kokous 1.2.07 Turku (Tiina Nokireki)
Project is financed by:
Ministry of Agriculture and Forestry joint research grant 2005-2007;
Evira;
EU reference laboratory: infection tests