Phage product launched to tackle winter ulcers

Bacteriophages are naturally occurring viruses that attack and kill their specific target bacteria, and ensure that no bacteria become too dominant. In 2018 STIM and sister company ACD Pharma launched the world’s first bacteriophage biocontrol product, Custus, which targets the bacteria causing yersiniosis in salmon. STIM says it is highly effective in removing Yersinia ruckeri bacteria from hatchery production water, biofilters and wellboats.

STIM’s second bacteriophage product, targeted at Moritella, was launched at the Lofoten Seminar hosted by STIM last week. In a press release, the company said Moritella viscosa, which attacks the skin of the fish causing sores and sepsis, was a big problem for fish farmers all along the Norwegian coastline during the winter. The effects on fish welfare were grave and earnings dropped due to quality down-grades.

Mutating bacteria

The rising number of Moritella outbreaks is linked to mutations in the bacteria, making available vaccines less effective. It is also linked with the widespread use of mechanical sea lice treatments on wellboats that may render the skin more vulnerable for infection from the bacteria.

“Wellboat transportation and sea lice treatments are stressful for the salmon, which causes it to shed bacteria in great amounts,” said STIM’s R&D director Hans Petter Kleppen. “Analyses of well water show the number of bacteria spiking fast, which of course greatly increases the chances of an outbreak.

“Adding our Yersinia bacteriophages to the water removes Yersinia ruckeri from the equation, as the number of these bacteria quickly drop to undetectable amounts. Lab results with our Moritella bacteriophages leads us to believe that the effect will be exactly the same for the new product.”

Scaling up

Moritella viscosa thrives in colder temperatures and STIM is working to have the new product available before the sea temperatures start to drop again. The summer will be spent on production scaling as well as necessary field- and safety tests.

The company’s chief executive, Roger Nordly, said: “Developing and getting a new vaccine approved takes a long time and we do not under any circumstances want to go back to using antibiotics in the amounts we did in the 80s and early 90s. That is why we have spent the last 12 years doing research on bacteriophages.

“We knew that we needed new tools in our toolbox and bacteriophages are just that. Together with effective vaccines it will play a major part in reducing the need for antibiotics and thereby reducing the development of antibiotic resistance, which is one of our greatest global health threats.”

Autogenic vaccines

As well as the bacteriophage product, STIM is also offering the possibility of producing autogenic vaccines, which are short term “emergency vaccines” based on isolates from single sites or locations.

“In collaboration with competent vaccine producers we will be able to deliver these vaccines within three months from receiving the needed isolates. If we act fast, we can be in much better shape going into the next Moritella season,” said Nordly.

Norway-based STIM has branches in Scotland, Canada the Faroes and Chile but its Yersinia bacteriophage product is currently only available in Norway.

“Work is under way to make it available in Scotland, Chile and other salmon producing countries as well,” STIM says on its UK website.