In aquatic animals, experimental studies are often used to study the pathogenicity of an etiologic agent; to study interactions between the host, pathogen, and environment; and to evaluate the comparative performance of existing and novel diagnostics. In the latter case, specimens are sometimes collected from animals at different stages of infection post-challenge to demonstrate temporal changes in diagnostic sensitivity post-challenge. Diagnostic accuracy studies should be designed to assess a test’s fitness for a designated purpose, and the design should also inform reporting in peer-reviewed journals. Reported studies should include clear descriptions of purpose and intended application, and authors should discuss the limitations of their results in the context of other available or currently-used tests to facilitate informed decisions by end-users. In human medical research, standards exist for various aspects of diagnostic test research, including guidelines for accurate and transparent reporting and for quality assessment of methodologies in systematic reviews of diagnostic-accuracy studies. Similar standards are required for animal, including aquatic animal, research. It is anticipated that the established criteria, from human clinical research for evaluating diagnostic accuracy studies, can be adapted to develop a standardized set of criteria for the design of field and experimental studies to assess diagnostic accuracy for infectious diseases in aquatic animals.

The ability to isolate viruses in cell culture is fundamental to disease diagnosis in both human and veterinary (including aquatic animals) medicine. The In addition, the ability to grow the virus in culture provides a potentially limitless source of pure virus and thus facilitates further characterisation of the virus and development of more sophisticated and improved diagnostic procedures. At present, virus isolation in cell culture remains, for most pathogenic viruses where cell culture systems have been developed, the most sensitive and reliable technique for the detection of viral pathogens of fish (OIE, 1995a).

The current lack of continuous prawn cell lines suitable for the isolation and growth of prawn viruses is a major set-back for the diagnosis of viral diseases of prawns (see Crane and Bernoth, 1996, for review); isolation and identification of the causative agents is severely hindered and the development of other diagnostic procedures is slowed.

The application of virus isolation in cell culture and the critical role it plays in certifying freedom of disease and controlling the spread of disease is exemplified by its use in the international trade of salmonid products (OIE, 1995a, b). Individual salmonid cell lines are susceptible to infection by a range of salmonid viruses and provide an essential tool for health surveillance and certification programs and is a requirement for the international trade of specific products. Similar regulations may, in the future, be required for international trade of penaeid products.

The aim of this project is to develop continuous prawn cell lines which are susceptible to infection by a range of prawn viruses, to develop diagnostic procedures using these cell lines and to demonstrate the application of these cell lines to the development of other diagnostic procedures for viral diseases (both exotic and enzootic) of prawns.

References

Crane, M. St. J. and Bernoth, E.-M. 1996. Molecular biology and fish disease diagnosis: Current status and future trends. In: Recent Advances in Microbiology (V. Asche, ed.), Aus. Soc. Microbiol. Vol. 4, pp. 41-82.

O.I.E. 1995a. International Aquatic Animal Health Code: Fish, Molluscs and Crustaceans. First edition. 184 pp. Paris, Office International des Epizooties.

O.I.E. 1995b. Diagnostic Manual for Aquatic Animal Diseases. First edition. 195 pp. Paris, Office International des Epizooties.