ARCHIVED - Waging War on Lice in Schools
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September 06, 2006— Ottawa, Ontario
Schools of fish, that is. Most of us probably associate lice with itchy school children, but underwater schools are also plagued by a different kind of lice. Sea lice are tiny parasites that feed on salmon, making the fish more susceptible to disease and infections that cause big economic losses for Canadians. NRC researchers in Halifax are working to help prevent and control these outbreaks, which can cost up to $60 million each year, worldwide.
|Salmon afflicted by sea lice|
Sea lice are also known as salmon louse or Lepeophtheirus salmonis. At the NRC Institute of Marine Biosciences (NRC-IMB), Dr. Neil Ross, Director of Research, Dr. Stewart Johnson, Senior Research Officer, and their team are studying the biochemical underpinnings of salmon and sea lice interactions. Parasites need to establish themselves and feed off host organisms in order to stay alive, but in doing so they also secrete various chemicals including proteins. The NRC team is closely examining how sea lice secretions interfere with a salmon's immunity to disease.
What happens during a sea lice infestation?
Once present on a salmon farm, hundreds or thousands of sea lice attach themselves to fish hosts. The sea lice feed off the salmon, weakening the fish and making them more susceptible to disease. In an effort to survive, salmon use up most of their energy pumping out sea water, hindering their growth. Salmon farmers end up feeding fish that don't grow and the unhealthy salmon stocks become worthless, unable to be sold for profit.
Using functional genomics, proteomics and biochemistry methods, NRC researchers identified that sea lice secrete certain digestive enzymes into the mucus of salmon. These enzymes help the sea lice feed and consequently suppress salmon immune responses. This harms salmon stocks and farms by making fish more susceptible to diseases. Dr. Ross and his team are also studying the role proteins in salmon mucus play in protecting against disease.
Though sea lice can be present in wild fish stocks, they are mostly found in high numbers in fish farms. And while salmon farming is still a relatively young industry, existing since the 1980s, it nonetheless plays a vital economic role in Canada's Atlantic and Pacific regions.
In an effort to minimize sea lice infestations and financial losses, some fish farmers try to separate young, susceptible fish from more mature and infected generations. Others introduce costly anti-parasitic drugs into their fish feed. However, Dr. Ross and his fellow NRC-IMB researchers have found another, more environmentally-friendly solution: they have patented the genes of secreted sea lice proteins and identified vaccine candidates.
Their research has led to the development and testing of a potentially, marketable vaccine against sea lice. It was developed with Microtek International Ltd., a private sector partner and NRC-IRAP client, located at NRC's industry partnership facility in Halifax.
To avoid interfering with successful fish vaccines already on the market and to minimize the number of injections to each fish, the new vaccine has to be incorporated with existing vaccines. It must also be meticulously tested in tanks and in sea cages and monitored for any adverse reactions. Researchers hope the new vaccine will protect future generations of salmon stocks from suffering the ravages of sea lice and reduce the potential spread of sea lice to wild salmon stocks. And in doing so, they expect to help minimize economic losses.
This sea lice collaborative project involved NRC-IMB and Microtek International, with initial funding provided by a Natural Sciences and Engineering Research Council (NSERC)/NRC Strategic Partners Grant with University of PEI/Atlantic Veterinary College collaborators led by Dr. John Burka.
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