Aquafin CRC - Atlantic Salmon Aquaculture Subprogram: development of an AGD vaccine: phase II
Health is one of the major issues associated with intensive culture industries, including aquaculture. Unhealthy stock relates to unhealthy industry – higher production costs, reduced viability, poor market and public image. Outbreaks of infectious salmon anaemia (ISA) in Scotland resulted in some salmon companies going into receivership. The use of medication increases production costs and negatively impacts on the market.
In Australia, salmon aquaculture is relatively disease free, which provides a possible marketing advantage. However, Amoebic Gill Disease costs are 9.4% of the gross value of production; a significant production cost for farming Atlantic salmon in Tasmania. The disease outbreaks seem to intensify as the industry develops and now are prevalent not only during summer months but also in winter. Outputs of the CRC Health Program such as improved treatment of AGD infected fish, AGD risk forecasting ability and vaccine production against AGD will increase the profitability and competitiveness of the Australian salmon industry.
AGD is severely limiting further expansion of the industry because it ties up resources that could be directed elsewhere, and it limits farming sites due to reliance on freshwater for bathing. Current treatment of AGD while environmentally friendly is not viable in the long-term and alternatives are required. Other treatments may be more reliant on antibiotics or chemicals, a risk to the image of the industry. Although vaccine development can be seen as a high-risk research target the potential rewards justify the risk
Final report
Amoebic gill disease (AGD) is considered to be the most significant health problem for farmed Atlantic salmon in Tasmania, costing the industry an estimated $15-20 million pa. It is caused by the presence of Neoparamoeba spp. on the gills and if untreated can lead to death. Although some control of the disease is achieved by freshwater bathing, this procedure is not considered a viable, long-term solution. It is not fully efficacious – more than one treatment is usually required; it is very labour-intensive; it requires large volumes of freshwater, and is stressful to the fish, which further impacts on their health and growth. Furthermore, recent experience indicates an increase in the required frequency for freshwater bathing in an attempt to control the disease.
Vaccine development is part of a multifaceted approach to develop short-, medium- and long-term solutions to the control of AGD; development of a sub-unit vaccine being the long-term approach of the overall research strategy. The essential objective is to develop a set of strategies and tools to provide the salmon industry with a substantial reduction to the economic impact of AGD in an economically and environmentally sustainable way.
The most significant outcome of this project is the commencement in July 2007 of sea trials for the experimental DNA vaccine made up of six antigens shown to provide a relative increase in protection of approximately 40 percent in laboratory based amoebic gill disease (AGD) trials.
Keywords: Atlantic salmon, Neoparamoeba, DNA vaccine, recombinant protein, response
