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BBB seminar: Frank Nilsen

Salmon louse: Host recognition and immunomodulation

Frank Nilsen
Department of Biological Sciences, University of Bergen

Sea lice are fish ectoparasites and the salmon louse is the most common species on salmonids, including farmed Atlantic salmon. Salmon lice are one of the main reasons for economical loss in the salmon farming industry in Norway and the cost for control and treatment is between 5-10 billion NOK/year. Understanding details of salmon louse biology and host parasite interaction is necessary in order to develop new control tools in the future.

The salmon louse is specific to salmonids and does not settle on, or grow on other species. A fundamental question is related to how is this manifested and how the parasite is able to recognise the right host. Previous studies indicate that chemoreception may be important and by searching the salmon louse genome a set of ionotropic receptors (IRs) was identified as a candidate for mediating host specificity in this parasite. This has been evaluated experimentally.

Atlantic salmon are not able to clear salmon louse infections and there is no evidence for a strong immune response after infection. This is in contrast to several of the Pacific salmonids that are resistant and coho salmon (a Pacific salmon species) mounts a string of inflammatory responses to early stages of the salmon louse and can clear the infection. An understanding of the details of host parasite interaction is crucial to be able to develop new treatment tools in coming years. We have recently obtained new data on host parasite interaction and this will be presented.


Chairperson: Anders Goksøyr, Department of Biological Sciences