Developing Alphavirus Research Strategies for Scotland

There is a significant and rising cost to the Scottish trout and salmon industry as a result of infection with salmonid alphavirus (SAV), often associated with runting and production losses, according to a report on Fish Update.

Business data suggest that suspected salmon pancreas disease (PD) may be responsible for up to 40 per cent of total disease losses, almost 10 per cent of losses for marine salmon production.

A new four-year research programme on salmonid alphavirus has recently started at the Marine Scotland (MS) laboratory in Aberdeen with objectives which cover both fundamental and applied research.

This will include, for example, work on potentially important fundamental work on host-pathogen interactions, and more applied work by epidemiologists on characterising the frequency and period of infection on farms, seasonality and possible management associations.

On 4 August, a joint meeting with aquaculture business representatives and scientists from MS was held in Inverness. The morning session included presentations by government, university and industry scientists and veterinarians. An afternoon session was jointly chaired by Heather Jones and Rob Raynard from MS and John Webster from the Scottish Salmon Producers Organisation (SSPO).

One of the key objectives was to develop further links and partnerships with industry and researchers to ensure that MS and all parties with concern for combating PD are making best use of available resources. The meeting enabled a good awareness of issues and that research must provide information of practical use and this led to open discussion regarding future work, and ideas on how to strengthen collaboration. Mechanisms for the provision of industry data for research were agreed as well as regular feedback from the project was widely discussed including the production of a newsletter, along with the advantages of being able to analyse further farm data. Opinions on vaccination within industry were also discussed and may be reviewed at subsequent meetings. Recent research at MS has led to improvements to our diagnostic methods and represents a practical outcome for the management of this disease.

Work to establish the circumstances that trigger mortality events on positive sites has also been compared, including the period when the risk from SAV might be reduced and farms can continue with normal husbandry procedures. An important research area included in the current project will require subtype pathogenesis studies as well as understanding the role of vectors and reservoirs to help to limit transmission. Finally, research is required to ensure that there is good recovery of surviving fish in terms of growth potential and flesh quality.

Alphavirus infection remains a severe problem in Norway and Ireland, and MS will continue to support the tri-nation initiative whereby research ideas and information are exchanged between scientists and industry representatives so that the Scottish fish farm industry can benefit.

David Bruno leads the pathology and bacteriology section within the Aquaculture and Animal Health Programme at the Marine Laboratory, Aberdeen. His group are responsible for the histological, bacteriological and parasitological diagnosis of infectious and non- infectious agents from farmed and wild fish and shellfish.