Phages to the rescue for the Norwegian farmed salmon
It is with great pride that I can announce the latest grant in our group by Thomas Sicheritz-Pontén. The grant secured 9,581,000 NOK ~ 6.950.750 DKK from FHF, which is the Norwegian Seafood Research Fund. The full description of the project is now online at their website and can be found here (English description is hiding under the Norwegian tabs...)
The project title is "Genomic epidemiology and Phage-based Prevention of salmon associated Pasteurella (GP3)" with the main objective to develop a targeted phage therapy solution to prevent and control Pasteurella skyensis and other strains associated with pasteurellosis in Atlantic salmon farms.
Pasteurella, the causative agent of pasteurellosis, is an increasingly emerging threat for farmed Norwegian salmon, and despite its implications and impact on fish stocks, little is known about this infectious agent. Antibiotic treatments are generally discouraged, vaccine development is still in its infancy and no specific effective treatments currently exist.
An obvious, targeted and timely approach to remove Pasteurella from Salmon is to utilise bacteriophages the natural predators of bacteria. Bacteriophages, or phages for short, are viruses that specifically infect and kill bacteria without infecting, or further impacting animal cells. Each phage type is able to infect and kill a narrow range of bacterial strains, which makes them suitable for development into highly precise antimicrobials. They can be applied to the water directly to kill bacteria and can be thought of as a unique ‘live’ antibacterial, to bridge the line between antibiotics and vaccines, making antimicrobial therapy more targeted and preventing problems associated with antibiotic resistance. Unlike vaccines, phages can both remove disease from fish and reduce disease spread within the wider environment lowering the chances for wild fish to be infected. The phage concentration in the environment is self-regulated as a phage cannot be active when there is no host to infect and its ability to strictly eliminate the pathogen population without affecting any other commensal microflora, makes them very promising disease control agents.
Phages have been successfully used to remove undesirable bacteria both in medicine, agriculture and other industries. In aquaculture, phage therapy is a particularly attractive option as applying in liquid conditions suits the natural biology of phages, increasing their ability to find and kill their target bacterial hosts. Phages have been used to remove pathogenic bacteria from fish and seafood including shrimp, oysters, lobsters, sea cucumbers, salmon and cod. Data consistently demonstrate that phages cause a significant reduction in pathogen load whilst having minimal impact on the environment. Recently, our partner ACD Pharma, a Norwegian aquaculture pharmaceutical company, launched its first phage-based product CUSTUS®️yrs, which effectively uses Yersinia ruckeri-specific phages to control the contagious disease yersiniosis in Atlantic salmon.
It is anticipated that the proposed bacteriophage-based studies for salmon Pasteurella control will provide the data needed for the subsequent development of a novel product that will ultimately improve salmon health and prevent stocks from being decimated by this pernicious pathogen.