Celia Agusti-Ridaura (Photo: Mari M. Press/Norwegian Veterinary Institute)
Sneaky sea lice vaccine in the works
Monday, January 07, 2013, 23:20 (GMT + 9)
Scientists are attempting to turn the tables on sea lice by providing salmon’s immune system with a defence to the parasites. The plan of scientists from the Norwegian Veterinary Institute is to develop a vaccine that will allow the salmon's immune system to itself kill the parasites.
Celia Agusti-Ridaura from the University of Valencia in Spain, currently at the Norwegian Veterinary Institute, explained that actually salmon already possesses a good resistance to microbes, thanks to various active immune molecules, including a network of factors called the complement system.
When infested by sea lice, the parasites feed on the fish’s blood, and the complement system in fish are supposed to cause corrosion on the intestinal wall of the parasite. However, the defense systems of sea lice restrain this immune effect, protecting them.
Scientists want to eliminate lice’s advantage.
"If a vaccine can neutralize these defense molecules in the parasite, salmon blood will become a 'problem food' for lice," said Agusti-Ridaura.
The hope is to find and isolate these defense molecules in the sea lice and incorporate them into a vaccine for salmon, that will expose fish to a component of the parasite's defense system and thus allow salmon to produce antibodies against the defenses of sea lice. Then, when sea lice feed on the blood of salmon, they will swallow antibodies against their own defense system, sabotaging their defence against the fish’s complement system.
This strategy would let the salmon's own immune molecules efficiently and unhindered cope with the parasite from within, making the use of antibiotics and other methods in the aquaculture industry irrelevant.
"To get there, there is still a lot of work to be done," added Agusti-Ridaura.
First, scientists must identify and isolate the molecules from the parasite's defense system. Currently, one of the key molecules has been put into a vaccine that is being tested at The Institute of Marine Research.
"We are now midway in this experiment and very excited about the outcome," she said. "We believe that the technique can be transferred to fight other blood-sucking parasites, and have already been in contact with the salmon industry in Chile to look at the opportunity to fight the lice variant there with the same method."
Agusti-Ridaura thinks this method could allow for the development of a vaccine that would fight the so-called Sparicotyle chrysophrii, a parasite similar to Gyrodactylus that affects the Spanish fish farming industry. Ideally, she told, this vaccine approach could also be used against ectoparasites of land animals, such as blood-sucking lice of domesticated animals.
By Natalia Real