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United States Department of Agriculture

Agricultural Research Service

Title: A New Technique for the Detection and Quantitative Analysis of Ihnv in Salmonids.

Authors
item Overturf, Kenneth
item Lapatra, Scott - CLEAR SPRINGS FOODS INC.,
item Powell, Madison - UNIVERSITY OF IDAHO,HFCES

Submitted to: Journal of Fish Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 1, 2001
Publication Date: July 1, 2001

Interpretive Summary: Disease management and assessment of hatchery reared fish and wild stocks are a major concern to commercial fish producers and fisheries conservationists. Infectious hematopoietic necrosis virus (IHNV) is a pathogenic microorganism that is responsible for significant economic losses in salmonid species. Typically, determination of viral presence occurs by isolating the virus from tissue culture or via the amplification of specific nucleotide sequences using polymerase chain reaction (PCR). A study was initiated to determine if a new method of sequence detection, termed real time PCR, could be used for the detection and quantification of IHNV, and how it compared to traditional methods. Following research it was concluded that this new method was extremely sensitive in detecting viral presence, over 100 times more sensitive than traditional PCR methods. Real time PCR was successful in detecting virus from infected fish and contaminated samples, proving to be as accurate as tissue culture assays yet much quicker. This new technique can be used to detect the presence of any pathogenic organism in a rapid and efficient manner and has the potential to significantly reduce economic losses from fish stocks by determining the presence and concentration of harmful microorganisms before they run their disease course through an infected population.

Technical Abstract: The rapid identification and quantification of virus in diseased fish is a goal both conservationists and commercial aquaculturists have struggled to attain. Recently a technique for the detection of viral mRNA particles that uses fluorescent tagging and amplification has been developed. Utilizing primers and fluorescent labeled probes generated for the specific identification of the nucleocapsid (N) and glycoprotein (G) genes of infectious hematopoietic necrosis virus (IHNV), and an instrument that measures cyclic emittance of fluorescence, the presence or absence of virus can be easily and rapidly confirmed. This method is not only useful in confirming viral presence but is effective in measuring the relative or absolute quantity of virus present within the sample. This allows for the determination of the health status of a carrier fish by measuring the quantity of viral genomes or transcribed viral genes present. Because this method is based on sequence detection, instead of virus isolation in cell culture, it is also effective in determining the presence of pathogenic organisms from water, fish feeds, or other potential reservoirs of infection.

Last Modified: 11/25/2014
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