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KHV Quick Test: Rapid On Site Diagnostic

by the Fish Site Editor
23 November 2008, at 12:00am

Both the ornamental fish industry and the aquaculture are continuously threatened by fish diseases which can cause considerableeconomic losses. One of the biggest problems is the import and spread of pathogens as a result of the international fish trade.

Consequently, rapid detection and reliable identification of pathogens is crucial for effective fish pathogen diagnosis, fish disease management and prevention (biosecurity) strategies. Over a period of a few years, Koi Herpes Virus (KHV), a lethal disease in carp and koi, has become one of the most important viral diseases in the trade of Koi carp worldwide. Recently, a reliable test based on BLUSPOT® technology has been developed for on site KHV detection within 5 minutes.

Koi Herpes Virus

Koi herpes virus (KHV), a highly contagious virus to fish, can cause significant morbidity and mortality in common carp (Cyprinus carpio), koi carp (C. carpio koi) and C. carpio gio. Presence of the virus was not reported until 1998 when it was detected in common carp and koi carp in Israel and the United States, after which other and additional cases have been found in the United States, Europe and Asia.

In general, the presence (or absence) of KHV is determined by specialized laboratories using relatively time-consuming techniques in a laboratory environment. Although generally accurate results are obtained, in many cases the results are generated to slow to be useful for disease management or prevention (biosecurity) decisions.

Therefore, increasingly fish breeders, exporters, importers and veterinarians are looking for a quick and reliable, in farm diagnostic test for the detection and identification of KHV. For this purpose, recently a KHV Quick Test based on BLUSPOT® technology has been succesfully developed. Some general features of BLUSPOT® technology are given below.

BLUSPOT® Technology

BLUSPOT® technology is a universal membrane-based detection technique which combines an immunological and enzymatic reaction and may address the market of laboratories that don’t have automated testing equipment. BLUSPOT® technology can be used as a platform for development of rapid tests in high potential and/or niche applications (e.g. environment, veterinary sector, and detection of allergens).

The technology is based on filtration (flow through) of reagents through a membrane on which a capture agent specific of the molecule to be detected is bound. In case of a positive result, an enzymatic reaction leads to the formation of a precipitated blue spot within 5 minutes.

From sampling to detection in 5 minutes

The sample to be tested (e.g. water, blood, serum, tissue, environmental sample) migrates through a membrane on which specific antibodies are coated. Antigen-antibody complexes are revealed by the use of a “conjugate” enzyme. After addition of an insoluble precipitating substrate, and a stopping solution, a permanent blue coloured spot is obtained, for which the intensity is proportional to the concentration of the target. As a result, the method does not only allow accurate detection, but also quantification.

Results may be interpreted visually (qualitative or semi-quantitative interpretation by comparison with a reference colour chart) or by the use of a reflectance reader (quantitative determination).

Innovative aspects/Advantages/ Special features

  • BLUSPOT® technology features the same performances as automated laboratory methods without the need of laboratory equipments.
  • The procedure is easy to use and rapid without dubious interpretation.
  • The test procedure is simple, fast (< 5 minutes) and well standardized.
  • Sensitivity is equal laboratory methods for serological diagnosis.
  • This technology makes on site KHV detection possible within a few minutes

Acknowledgements

This research is financially supported by the ‘Vlaams Instituut voor de bevordering van het Wetenschappelijk-Technologisch Onderzoek- Vlaanderen’.

November 2008

the Fish Site Editor