Aquaculture and Fisheries News => Aquaculture News => ข้อความที่เริ่มโดย: pramaiporn ที่ สิงหาคม 25, 2010, 07:54:27 AM

หัวข้อ: Genetic test identifies IPN resistant salmon
เริ่มหัวข้อโดย: pramaiporn ที่ สิงหาคม 25, 2010, 07:54:27 AM
In 2009 alone, 220 viral outbreaks of IPN took place in Norwegian salmon centres. (Photo: Aqua Gen/ FIS)

Genetic test identifies IPN resistant salmon

Wednesday, August 25, 2010, 01:00 (GMT + 9)

The Norwegian company Aqua Gen has created a commercial genetic test that swiftly establishes the salmon with the highest resistance to the infectious pancreatic necrosis (IPN) virus. Recently launched, the product might represent a tremendous step forward in the eradication of this exorbitant disease.

Researchers at Aqua Gen and Nofima Marin and at the Centre for Integrative Genetics (CIGENE) identified the markers for a gene that makes salmon stronger against the IPN virus. The discovery is now being executed toward selective breeding, with Aqua Gen already delivering QTL eggs from parent fish screened for genetic resistance to IPN.

“Remarkably, the gene explains 80 per cent of the variation in resistance to IPN in salmon,” said Thomas Moen, molecular geneticist and project manager of Aqua Gen. “This gene is nearly as strong a determinant as the one that determines eye colour in humans.”

The finding allows scientists to select for broodstock with the maximum probability of generating offspring protected from the IPN virus. The test requires only a blood or tissue sample.

“When we select two parent fish with good IPN resistance, their offspring is practically immune to the disease,” Moen explained.

Aqua Gen is achieving added value of 30-40 per cent on the market due to its QTL eggs versus products without genetic testing.

“We will be the first breeding company in aquaculture to use DNA for selecting broodstock,” noted Odd Magne Rødseth, CEO of Aqua Gen.

Currently, IPN produces high mortality among production fish stocks, mainly in the early production phases.

Genetic testing to choose higher disease resistance will substitute conventional challenge testing, which requires that 80,000 to 100,000 fish in each generation be exposed to the virus.

The researchers still are ignorant as to which gene gives salmon immunity to the virus, but efforts are underway through a collaborative effort between Canada, Norway and Chile. Norway is providing almost 40 per cent of the capital via a joint investment by the Norwegian industry and public funding instruments.

“It will be exciting to understand the immune mechanisms involved,” added Rødseth. “Finding them will have an impact far beyond our selective breeding work.”

In 2009 alone, 220 viral outbreaks of IPN took place in Norwegian salmon production sites -- 158 per cent more outbreaks than in 2008, according to the National Veterinary Institute. IPN troubles farmers worldwide in both seawater and fresh water.

Because IPN hits the fish’s early life stages, it has been hard to devise effective vaccines and vaccination regimes to restrain the outbreaks.

IPN has struck species from halibut, cod, eels and octopus to shellfish and crustaceans.

In salmon, the virus kills cells that compose digestive enzymes, so despite an apparently steady appetite, infected fish starve because they cannot digest fat and protein.

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By Natalia Real