International Waters: Possible End-of-Year Date for DNA-Multiscan
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|This Pseudodoras granulosus has badly rotted fins, especially the anal and caudal. Numerous patho-gens can cause this condition; however, using current methods, each one needs separate testing. DNA-Multiscanning can test for all of them at once.|
The DNA-Multiscan program remains on schedule and could wrap up by the end of 2009, reports scientists involved in developing this revolutionary approach to fish-disease diagnostics.
DNA-Multiscanning will allow simultaneous identification of more than 60 pathogens (disease-causing agents), and within just 36 hours. While demanding the application of specialized techniques and the skills of appropriately trained personnel, DNA-Multiscanning is—in principle—quite simple.
It involves the comparison of the DNA of a known, unknown or even suspected pathogen with the DNA of known reference pathogens.
The DNA are brought into contact with each other and given the opportunity to fuse (hybridize); however, hybridization can only occur between identical or very similar, strands of DNA.
Therefore, the higher the degree of hybridization, the closer the relationship will be between the known, unknown or suspected pathogen and a known reference pathogen. This not only allows for rapid diagnosis, but also for testing multiple diseases in one go, saving an enormous amount of time and reducing costs.
The reference DNA collection already boasts 20 pathogenic bacteria, including some well known ones, such as Aeromonas hydrophila (hemorrhagic septicemia) and A. salmonicida furunculosis (goldfish ulcer disease) and other diseases. The collection also includes some lesser-known types, such as Vagococcus salmoninarum, which was recently associated with one of the emerging diseases in rainbow trout, coldwater “streptococcosis.” The reference collection also added four viruses: koi herpesvirus (KHV); infectious hematopoietic necrosis virus (IHNV); viral hemorrhagic septicemia virus (VHSV); and spring viraemia of carp virus (SVCV).
The diagnostic techniques for detecting Flavobacterium (columnaris) and Mycobacterium (fish tuberculosis) are also improved. In addition, the scanning program demonstrated a correlation between Flavobacterium, Aeromonas and KHV, although DNA-Multiscanning is able to demonstrate coincidence between the three pathogens, it cannot determine whether KHV induces fish to become susceptible to the two bacteria, or vice-versa.
Finally, a database is being set up to include biophysical factors. By including parameters such as pH, temperature, etc., it should eventually be possible to correlate certain environmental conditions with particular diseases.
Researchers at the Scientia Terrae Research Institute in Belgium are optimistic that the progress they are making should allow them to meet their completion target date of the end of 2009. If so, it will not be long before the ornamental-fish sector enters the long-awaited new era of fish diagnosis and treatment. <HOME>
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