Strategic plan
This proposal is part of the FRDC Industry Development Program, Strategy – Aquaculture Development – Production and Production Systems. The project includes a technician and a postdoctoral research fellow (Dr Philip Crosbie) as co-investigator and they will both be provided with suitable professional development opportunities through the Education Program of the Aquafin CRC. Later in the project it may be possible to adopt a PhD student with an independent scholarship or include Honours and Masters projects as they are required and become available. Thus, the project will contribute to the Human Capital Development Program, Leadership and Vocational Development. This proposal includes several key research areas outlined in the Aquatic Animal Health Subprogram Strategic R&D Plan, namely the Nature of disease and host-pathogen interactions and Training and capacity building. Relevant priorities being: to provide improved knowledge of the biology of disease agents (in this case the AGD-causing organism), and an improved knowledge of host responses to disease agents which will be partially addressed by monitoring the specific antibody response to N. pemaquidensis antigens (Nature of disease and host-pathogen interactions). Both the research and service components of this proposal will expand the technical skill base in aquatic animal health and facilitate R&D knowledge transfer (Training and capacity building). This project will underpin other projects that contribute to the Aquafin CRC Health Program Outcomes ie. reduced economic impact of disease (AGD) in finfish (Atlantic salmon) farming.

Need for this research
The continued existence of Atlantic salmon farming in Tasmania is threatened by AGD. Production is expected to increase over the next few years and this will undoubtedly lead to an increase in the incidence of AGD. The AGD control method of freshwater bathing has increased in frequency with the growth in production over the past few years and this trend is expected to continue. This will present a growing cost burden to salmon growers, it is therefore imperative that the impact of AGD on the industry be reduced so as to maintain viability for the future. Multidisciplinary teams have been assembled to achieve this outcome via a number of projects. The projects are complementary and in some cases interdependent where progress in one area is dependent on progress in another area. This is particularly the case with the service component of the current proposal and the vaccine development program, where supply of infective material and a means of controlled testing of candidate vaccines are integral to success. Vaccine development requires identification of specific antigens from the pathogen that will elicit a protective immune response in the host, hence the need for significant quantities of infective material. Similarly, success of the treatment of AGD investigation is dependent on supply of cells for initial screening of a battery of potential therapeutants in vitro before attempting field trials. The research component of the proposal, which is the development of a standard AGD challenge method that can be used in experimental tanks, is essential for the success of these projects. We need to be able to consistently induce AGD in fish to economically appraise alternative treatments and candidate vaccines before moving onto costly field trials. Inducing experimental infections is widely recognised as one of the cornerstones of vaccine development (Nordmo, 1996).

Benefits
The major benefit will be enabling progress in the vaccine development and alternative treatment projects to be made. We will have in place a model to economically appraise novel treatments, experimental vaccines and other less specific means of prophylaxis such as immunomodulation. Ultimately the project will contribute to a collective outcome of lessening the impact of AGD on salmon producers and reducing the estimated 10-20% of production costs that is currently spent controlling the disease. Other benefits include a better understanding of risk factors contributing to AGD, and the opportunity to investigate the virulence mechanisms of the organism. Overall the project will contribute to research output and service. The systematic development and subsequent use of challenge models will yield publishable material. The service aspect will be in the supply of amoebae to collaborators and provision of a means to test novel therapeutants, experimental vaccines and immunomodulatory compounds.

References
Nordmo, R., 1996. Strengths and Weaknesses of Different Challenge Methods. In: Fish Vaccinology (ed. By Gudding, R., Lillehaug, A., Midtlyng, P.J. and Brown, F.) Developments in Biological Standardisation. Basel, Karger p 303-309