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Mouth rot in farmed Atlantic salmon

Alternative title: Munnråte hos opdrettet Atlantisk laks

Awarded: NOK 1.5 mill.

Project Number:


Project Period:

2015 - 2018

Funding received from:


Mouthrot is a major health and welfare problem in farmed Atlantic salmon in Western Canada, especially during the first few months following transfer into saltwater. This disease, associated with the bacterium Tenacibaculum maritimum, is the main reason the Atlantic salmon farming industry in this region including Cermaq continues to use antibiotics. Even though T. maritimum is the most extensively studied member of the genus Tenacibaculum there are still many unanswered questions. No commercially available vaccine is available against the bacterium, and there is limited knowledge regarding this pathogen?s routes of transmission, reservoirs and pathogenesis. This research project aims to gain knowledge about infections caused by T. maritimum and to find preventive measures against these infections. The main objective of this PhD-project "Mouthrot in farmed Atlantic salmon" is to gain new knowledge about T. maritimum and its role in causing mouthrot in Atlantic salmon, and to develop preventive measures to reduce the impact in salmon farming. The project will include a more detailed description of the bacteria using advanced molecular methods. A standardized infection model will be developed to investigate the feasibility of vaccination as a management tool for mouthrot caused by T. maritimum. Based on tests of antibody responses, vaccine candidates will be chosen to test in vaccine trials, and will help determine whether or not a vaccine could be a potential future solution. Transmission routes of the bacteria, as well as tissue tropism will be investigated using a real-time RT-PCR assay developed in initial studies. The knowledge obtained in the characterization of the bacteria will be important in this work.


Mouth Rot, caused by the bacteria Tencibaculum maritimum, has been a major disease problem in the production of Atlantic salmon on the West coast of Canada. Cermaq has experienced high mortality and downgrading at harvest due to Tenacibaculum maritimum infections. There is no commercially available vaccine against the bacterium, however, antibiotic treatment has limited the severity of the disease. Antibiotic treatment is not sustainable and therefore Cermaq established a research project in 2015 to build knowledge about Tenacibaculum maritimum infections, and to develop preventative measures. The main goal of this project "Mouth Rot in Atlantic salmon" is to gain more knowledge about Tenacibaculum maritimum and infections with this bacterium and develop preventive measures to reduce impact in salmon farming. This will be done by standardizing the infection model to be able to do vaccine tests and measure antibody response in infected fish to see if vaccination could be a solution. Field isolates will also be characterized genetically in order to investigate the diversity in the field. An antibody response test will be carried out by developing a vaccine candidate and running a vaccine trial. This will allow us to investigate if a vaccine could be solution in the future. It will also be important to attempt to find the optimal antibiotic treatment regime if vaccination is not an option in the future.

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