What is BKD?
Salmon infected with BKD |
Bacterial Kidney Disease (BKD) is a major health problem of cultured salmonids. The disease is caused by Renibacterium salmoninarum which causes lesions in the kidney and other organs. BKD is commonly diagnosed through invasive or lethal techniques applied to fresh or frozen tissues or blood plasma from infected fish. We are currently developing a nonlethal screening detection method based on near infrared spectroscopy. |
What is our research focus?
Spectral collction using a transmission probe |
The main focus of our ongoing investigation is to study the spectral features of living fish in controlled and infected populations. Weight, length, and spectral data are acquired on a weekly basis to examine the spectral changes over the course of the infection. Near infrared spectra are acquired by placing a fiber optic probe in direct contact with skin and scales of the fish. The spectroscopic information is then correlated to the BKD status of each fish, as determined by visual examination of kidney tissue and quantitative polymerase chain reaction (q-PCR) test. |
Scanning live fish on diffuse reflectance probe
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100 live juvenile Pacific salmon have been randomly divided into two 100 gallon tanks. Tanks are designated as “control” and “experimental,” each containing 50 fish. Fish in the experimental tank were exposed to a Renibacterium salmoninarum solution. |
100 gallon tank containg 50 infected salmon |
Fluoresced Renibacterium salmoninarum (BKD) in kidney tissue. |
Presence of Rs bacterium is verified by visual inspection of kidney tissues, ELISA assays, Quantitative Polymerase Chain Reaction (q-PCR), and a direct florescent antibody test (DFAT). |
How do we interpret the data?
Score plot from PCA: BKD infected (red) and healthy (black) fish. |
Categorization of fish according to their health is achieved in part by using Principal Component Analysis (PCA) and Soft Independent Modeling of Class Analogy (SIMCA). Detection of specific changes in body composition between healthy fish and those with BKD by near infrared spectroscopy may allow for development of a nonlethal screening method that recognizes presence of BKD in salmonids before development of external clinical signs. |
Second derivative transmission spectra recorded on BKD infected (red) and healthy (black) fish. |
What do we do next ?
2007 National ACS Meeting, Boston |
Currently, we are acquiring weight, length, and spectral measurements on the live fish on a weekly basis. We will continue to examine spectral, physical, and microbiological changes over the course of the infection.
Recently, student researchers presented this project at the 2007 National American Chemical Society Meeting in Boston.
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